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CouchPotatoServer/libs/sqlalchemy/sql/expression.py

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# sql/expression.py
# Copyright (C) 2005-2011 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Defines the base components of SQL expression trees.
All components are derived from a common base class
:class:`ClauseElement`. Common behaviors are organized
based on class hierarchies, in some cases via mixins.
All object construction from this package occurs via functions which
in some cases will construct composite :class:`ClauseElement` structures
together, and in other cases simply return a single :class:`ClauseElement`
constructed directly. The function interface affords a more "DSL-ish"
feel to constructing SQL expressions and also allows future class
reorganizations.
Even though classes are not constructed directly from the outside,
most classes which have additional public methods are considered to be
public (i.e. have no leading underscore). Other classes which are
"semi-public" are marked with a single leading underscore; these
classes usually have few or no public methods and are less guaranteed
to stay the same in future releases.
"""
import itertools, re
from operator import attrgetter
from sqlalchemy import util, exc
from sqlalchemy.sql import operators
from sqlalchemy.sql.visitors import Visitable, cloned_traverse
import operator
functions = util.importlater("sqlalchemy.sql", "functions")
sqlutil = util.importlater("sqlalchemy.sql", "util")
sqltypes = util.importlater("sqlalchemy", "types")
default = util.importlater("sqlalchemy.engine", "default")
__all__ = [
'Alias', 'ClauseElement', 'ColumnCollection', 'ColumnElement',
'CompoundSelect', 'Delete', 'FromClause', 'Insert', 'Join', 'Select',
'Selectable', 'TableClause', 'Update', 'alias', 'and_', 'asc', 'between',
'bindparam', 'case', 'cast', 'column', 'delete', 'desc', 'distinct',
'except_', 'except_all', 'exists', 'extract', 'func', 'modifier',
'collate', 'insert', 'intersect', 'intersect_all', 'join', 'label',
'literal', 'literal_column', 'not_', 'null', 'or_', 'outparam',
'outerjoin', 'select', 'subquery', 'table', 'text', 'tuple_', 'type_coerce',
'union', 'union_all', 'update', ]
PARSE_AUTOCOMMIT = util._symbol('PARSE_AUTOCOMMIT')
def desc(column):
"""Return a descending ``ORDER BY`` clause element.
e.g.::
order_by = [desc(table1.mycol)]
"""
return _UnaryExpression(column, modifier=operators.desc_op)
def asc(column):
"""Return an ascending ``ORDER BY`` clause element.
e.g.::
order_by = [asc(table1.mycol)]
"""
return _UnaryExpression(column, modifier=operators.asc_op)
def outerjoin(left, right, onclause=None):
"""Return an ``OUTER JOIN`` clause element.
The returned object is an instance of :class:`Join`.
Similar functionality is also available via the :func:`outerjoin()`
method on any :class:`FromClause`.
left
The left side of the join.
right
The right side of the join.
onclause
Optional criterion for the ``ON`` clause, is derived from
foreign key relationships established between left and right
otherwise.
To chain joins together, use the :func:`join()` or :func:`outerjoin()`
methods on the resulting :class:`Join` object.
"""
return Join(left, right, onclause, isouter=True)
def join(left, right, onclause=None, isouter=False):
"""Return a ``JOIN`` clause element (regular inner join).
The returned object is an instance of :class:`Join`.
Similar functionality is also available via the :func:`join()` method
on any :class:`FromClause`.
left
The left side of the join.
right
The right side of the join.
onclause
Optional criterion for the ``ON`` clause, is derived from
foreign key relationships established between left and right
otherwise.
To chain joins together, use the :func:`join()` or :func:`outerjoin()`
methods on the resulting :class:`Join` object.
"""
return Join(left, right, onclause, isouter)
def select(columns=None, whereclause=None, from_obj=[], **kwargs):
"""Returns a ``SELECT`` clause element.
Similar functionality is also available via the :func:`select()`
method on any :class:`FromClause`.
The returned object is an instance of :class:`Select`.
All arguments which accept :class:`ClauseElement` arguments also accept
string arguments, which will be converted as appropriate into
either :func:`text()` or :func:`literal_column()` constructs.
:param columns:
A list of :class:`ClauseElement` objects, typically
:class:`ColumnElement` objects or subclasses, which will form the
columns clause of the resulting statement. For all members which are
instances of :class:`Selectable`, the individual :class:`ColumnElement`
members of the :class:`Selectable` will be added individually to the
columns clause. For example, specifying a
:class:`~sqlalchemy.schema.Table` instance will result in all the
contained :class:`~sqlalchemy.schema.Column` objects within to be added
to the columns clause.
This argument is not present on the form of :func:`select()`
available on :class:`~sqlalchemy.schema.Table`.
:param whereclause:
A :class:`ClauseElement` expression which will be used to form the
``WHERE`` clause.
:param from_obj:
A list of :class:`ClauseElement` objects which will be added to the
``FROM`` clause of the resulting statement. Note that "from" objects are
automatically located within the columns and whereclause ClauseElements.
Use this parameter to explicitly specify "from" objects which are not
automatically locatable. This could include
:class:`~sqlalchemy.schema.Table` objects that aren't otherwise present,
or :class:`Join` objects whose presence will supercede that of the
:class:`~sqlalchemy.schema.Table` objects already located in the other
clauses.
:param autocommit:
Deprecated. Use .execution_options(autocommit=<True|False>)
to set the autocommit option.
:param prefixes:
a list of strings or :class:`ClauseElement` objects to include
directly after the SELECT keyword in the generated statement,
for dialect-specific query features.
:param distinct=False:
when ``True``, applies a ``DISTINCT`` qualifier to the columns
clause of the resulting statement.
:param use_labels=False:
when ``True``, the statement will be generated using labels
for each column in the columns clause, which qualify each
column with its parent table's (or aliases) name so that name
conflicts between columns in different tables don't occur.
The format of the label is <tablename>_<column>. The "c"
collection of the resulting :class:`Select` object will use these
names as well for targeting column members.
:param for_update=False:
when ``True``, applies ``FOR UPDATE`` to the end of the
resulting statement. Certain database dialects also support
alternate values for this parameter, for example mysql
supports "read" which translates to ``LOCK IN SHARE MODE``,
and oracle supports "nowait" which translates to ``FOR UPDATE
NOWAIT``.
:param correlate=True:
indicates that this :class:`Select` object should have its
contained :class:`FromClause` elements "correlated" to an enclosing
:class:`Select` object. This means that any :class:`ClauseElement`
instance within the "froms" collection of this :class:`Select`
which is also present in the "froms" collection of an
enclosing select will not be rendered in the ``FROM`` clause
of this select statement.
:param group_by:
a list of :class:`ClauseElement` objects which will comprise the
``GROUP BY`` clause of the resulting select.
:param having:
a :class:`ClauseElement` that will comprise the ``HAVING`` clause
of the resulting select when ``GROUP BY`` is used.
:param order_by:
a scalar or list of :class:`ClauseElement` objects which will
comprise the ``ORDER BY`` clause of the resulting select.
:param limit=None:
a numerical value which usually compiles to a ``LIMIT``
expression in the resulting select. Databases that don't
support ``LIMIT`` will attempt to provide similar
functionality.
:param offset=None:
a numeric value which usually compiles to an ``OFFSET``
expression in the resulting select. Databases that don't
support ``OFFSET`` will attempt to provide similar
functionality.
:param bind=None:
an ``Engine`` or ``Connection`` instance to which the
resulting ``Select ` object will be bound. The ``Select``
object will otherwise automatically bind to whatever
``Connectable`` instances can be located within its contained
:class:`ClauseElement` members.
"""
return Select(columns, whereclause=whereclause, from_obj=from_obj,
**kwargs)
def subquery(alias, *args, **kwargs):
"""Return an :class:`Alias` object derived
from a :class:`Select`.
name
alias name
\*args, \**kwargs
all other arguments are delivered to the
:func:`select` function.
"""
return Select(*args, **kwargs).alias(alias)
def insert(table, values=None, inline=False, **kwargs):
"""Return an :class:`Insert` clause element.
Similar functionality is available via the :func:`insert()` method on
:class:`~sqlalchemy.schema.Table`.
:param table: The table to be inserted into.
:param values: A dictionary which specifies the column specifications of
the ``INSERT``, and is optional. If left as None, the column
specifications are determined from the bind parameters used during the
compile phase of the ``INSERT`` statement. If the bind parameters also
are None during the compile phase, then the column specifications will be
generated from the full list of table columns. Note that the
:meth:`~Insert.values()` generative method may also be used for this.
:param prefixes: A list of modifier keywords to be inserted between INSERT
and INTO. Alternatively, the :meth:`~Insert.prefix_with` generative
method may be used.
:param inline: if True, SQL defaults will be compiled 'inline' into the
statement and not pre-executed.
If both `values` and compile-time bind parameters are present, the
compile-time bind parameters override the information specified
within `values` on a per-key basis.
The keys within `values` can be either :class:`~sqlalchemy.schema.Column`
objects or their string identifiers. Each key may reference one of:
* a literal data value (i.e. string, number, etc.);
* a Column object;
* a SELECT statement.
If a ``SELECT`` statement is specified which references this
``INSERT`` statement's table, the statement will be correlated
against the ``INSERT`` statement.
"""
return Insert(table, values, inline=inline, **kwargs)
def update(table, whereclause=None, values=None, inline=False, **kwargs):
"""Return an :class:`Update` clause element.
Similar functionality is available via the :func:`update()` method on
:class:`~sqlalchemy.schema.Table`.
:param table: The table to be updated.
:param whereclause: A :class:`ClauseElement` describing the ``WHERE``
condition of the ``UPDATE`` statement. Note that the
:meth:`~Update.where()` generative method may also be used for this.
:param values:
A dictionary which specifies the ``SET`` conditions of the
``UPDATE``, and is optional. If left as None, the ``SET``
conditions are determined from the bind parameters used during
the compile phase of the ``UPDATE`` statement. If the bind
parameters also are None during the compile phase, then the
``SET`` conditions will be generated from the full list of table
columns. Note that the :meth:`~Update.values()` generative method may
also be used for this.
:param inline:
if True, SQL defaults will be compiled 'inline' into the statement
and not pre-executed.
If both `values` and compile-time bind parameters are present, the
compile-time bind parameters override the information specified
within `values` on a per-key basis.
The keys within `values` can be either :class:`~sqlalchemy.schema.Column`
objects or their
string identifiers. Each key may reference one of:
* a literal data value (i.e. string, number, etc.);
* a Column object;
* a SELECT statement.
If a ``SELECT`` statement is specified which references this
``UPDATE`` statement's table, the statement will be correlated
against the ``UPDATE`` statement.
"""
return Update(
table,
whereclause=whereclause,
values=values,
inline=inline,
**kwargs)
def delete(table, whereclause = None, **kwargs):
"""Return a :class:`Delete` clause element.
Similar functionality is available via the :func:`delete()` method on
:class:`~sqlalchemy.schema.Table`.
:param table: The table to be updated.
:param whereclause: A :class:`ClauseElement` describing the ``WHERE``
condition of the ``UPDATE`` statement. Note that the
:meth:`~Delete.where()` generative method may be used instead.
"""
return Delete(table, whereclause, **kwargs)
def and_(*clauses):
"""Join a list of clauses together using the ``AND`` operator.
The ``&`` operator is also overloaded on all
:class:`_CompareMixin` subclasses to produce the
same result.
"""
if len(clauses) == 1:
return clauses[0]
return BooleanClauseList(operator=operators.and_, *clauses)
def or_(*clauses):
"""Join a list of clauses together using the ``OR`` operator.
The ``|`` operator is also overloaded on all
:class:`_CompareMixin` subclasses to produce the
same result.
"""
if len(clauses) == 1:
return clauses[0]
return BooleanClauseList(operator=operators.or_, *clauses)
def not_(clause):
"""Return a negation of the given clause, i.e. ``NOT(clause)``.
The ``~`` operator is also overloaded on all
:class:`_CompareMixin` subclasses to produce the
same result.
"""
return operators.inv(_literal_as_binds(clause))
def distinct(expr):
"""Return a ``DISTINCT`` clause."""
expr = _literal_as_binds(expr)
return _UnaryExpression(expr, operator=operators.distinct_op, type_=expr.type)
def between(ctest, cleft, cright):
"""Return a ``BETWEEN`` predicate clause.
Equivalent of SQL ``clausetest BETWEEN clauseleft AND clauseright``.
The :func:`between()` method on all
:class:`_CompareMixin` subclasses provides
similar functionality.
"""
ctest = _literal_as_binds(ctest)
return ctest.between(cleft, cright)
def case(whens, value=None, else_=None):
"""Produce a ``CASE`` statement.
whens
A sequence of pairs, or alternatively a dict,
to be translated into "WHEN / THEN" clauses.
value
Optional for simple case statements, produces
a column expression as in "CASE <expr> WHEN ..."
else\_
Optional as well, for case defaults produces
the "ELSE" portion of the "CASE" statement.
The expressions used for THEN and ELSE,
when specified as strings, will be interpreted
as bound values. To specify textual SQL expressions
for these, use the :func:`literal_column`
construct.
The expressions used for the WHEN criterion
may only be literal strings when "value" is
present, i.e. CASE table.somecol WHEN "x" THEN "y".
Otherwise, literal strings are not accepted
in this position, and either the text(<string>)
or literal(<string>) constructs must be used to
interpret raw string values.
Usage examples::
case([(orderline.c.qty > 100, item.c.specialprice),
(orderline.c.qty > 10, item.c.bulkprice)
], else_=item.c.regularprice)
case(value=emp.c.type, whens={
'engineer': emp.c.salary * 1.1,
'manager': emp.c.salary * 3,
})
Using :func:`literal_column()`, to allow for databases that
do not support bind parameters in the ``then`` clause. The type
can be specified which determines the type of the :func:`case()` construct
overall::
case([(orderline.c.qty > 100,
literal_column("'greaterthan100'", String)),
(orderline.c.qty > 10, literal_column("'greaterthan10'",
String))
], else_=literal_column("'lethan10'", String))
"""
return _Case(whens, value=value, else_=else_)
def cast(clause, totype, **kwargs):
"""Return a ``CAST`` function.
Equivalent of SQL ``CAST(clause AS totype)``.
Use with a :class:`~sqlalchemy.types.TypeEngine` subclass, i.e::
cast(table.c.unit_price * table.c.qty, Numeric(10,4))
or::
cast(table.c.timestamp, DATE)
"""
return _Cast(clause, totype, **kwargs)
def extract(field, expr):
"""Return the clause ``extract(field FROM expr)``."""
return _Extract(field, expr)
def collate(expression, collation):
"""Return the clause ``expression COLLATE collation``."""
expr = _literal_as_binds(expression)
return _BinaryExpression(
expr,
_literal_as_text(collation),
operators.collate, type_=expr.type)
def exists(*args, **kwargs):
"""Return an ``EXISTS`` clause as applied to a :class:`Select` object.
Calling styles are of the following forms::
# use on an existing select()
s = select([table.c.col1]).where(table.c.col2==5)
s = exists(s)
# construct a select() at once
exists(['*'], **select_arguments).where(criterion)
# columns argument is optional, generates "EXISTS (SELECT *)"
# by default.
exists().where(table.c.col2==5)
"""
return _Exists(*args, **kwargs)
def union(*selects, **kwargs):
"""Return a ``UNION`` of multiple selectables.
The returned object is an instance of
:class:`CompoundSelect`.
A similar :func:`union()` method is available on all
:class:`FromClause` subclasses.
\*selects
a list of :class:`Select` instances.
\**kwargs
available keyword arguments are the same as those of
:func:`select`.
"""
return CompoundSelect(CompoundSelect.UNION, *selects, **kwargs)
def union_all(*selects, **kwargs):
"""Return a ``UNION ALL`` of multiple selectables.
The returned object is an instance of
:class:`CompoundSelect`.
A similar :func:`union_all()` method is available on all
:class:`FromClause` subclasses.
\*selects
a list of :class:`Select` instances.
\**kwargs
available keyword arguments are the same as those of
:func:`select`.
"""
return CompoundSelect(CompoundSelect.UNION_ALL, *selects, **kwargs)
def except_(*selects, **kwargs):
"""Return an ``EXCEPT`` of multiple selectables.
The returned object is an instance of
:class:`CompoundSelect`.
\*selects
a list of :class:`Select` instances.
\**kwargs
available keyword arguments are the same as those of
:func:`select`.
"""
return CompoundSelect(CompoundSelect.EXCEPT, *selects, **kwargs)
def except_all(*selects, **kwargs):
"""Return an ``EXCEPT ALL`` of multiple selectables.
The returned object is an instance of
:class:`CompoundSelect`.
\*selects
a list of :class:`Select` instances.
\**kwargs
available keyword arguments are the same as those of
:func:`select`.
"""
return CompoundSelect(CompoundSelect.EXCEPT_ALL, *selects, **kwargs)
def intersect(*selects, **kwargs):
"""Return an ``INTERSECT`` of multiple selectables.
The returned object is an instance of
:class:`CompoundSelect`.
\*selects
a list of :class:`Select` instances.
\**kwargs
available keyword arguments are the same as those of
:func:`select`.
"""
return CompoundSelect(CompoundSelect.INTERSECT, *selects, **kwargs)
def intersect_all(*selects, **kwargs):
"""Return an ``INTERSECT ALL`` of multiple selectables.
The returned object is an instance of
:class:`CompoundSelect`.
\*selects
a list of :class:`Select` instances.
\**kwargs
available keyword arguments are the same as those of
:func:`select`.
"""
return CompoundSelect(CompoundSelect.INTERSECT_ALL, *selects, **kwargs)
def alias(selectable, alias=None):
"""Return an :class:`Alias` object.
An :class:`Alias` represents any :class:`FromClause`
with an alternate name assigned within SQL, typically using the ``AS``
clause when generated, e.g. ``SELECT * FROM table AS aliasname``.
Similar functionality is available via the :func:`alias()` method
available on all :class:`FromClause` subclasses.
selectable
any :class:`FromClause` subclass, such as a table, select
statement, etc..
alias
string name to be assigned as the alias. If ``None``, a
random name will be generated.
"""
return Alias(selectable, alias=alias)
def literal(value, type_=None):
"""Return a literal clause, bound to a bind parameter.
Literal clauses are created automatically when non- :class:`ClauseElement`
objects (such as strings, ints, dates, etc.) are used in a comparison
operation with a :class:`_CompareMixin`
subclass, such as a :class:`~sqlalchemy.schema.Column` object. Use this function to force the
generation of a literal clause, which will be created as a
:class:`_BindParamClause` with a bound value.
:param value: the value to be bound. Can be any Python object supported by
the underlying DB-API, or is translatable via the given type argument.
:param type\_: an optional :class:`~sqlalchemy.types.TypeEngine` which
will provide bind-parameter translation for this literal.
"""
return _BindParamClause(None, value, type_=type_, unique=True)
def tuple_(*expr):
"""Return a SQL tuple.
Main usage is to produce a composite IN construct::
tuple_(table.c.col1, table.c.col2).in_(
[(1, 2), (5, 12), (10, 19)]
)
"""
return _Tuple(*expr)
def type_coerce(expr, type_):
"""Coerce the given expression into the given type, on the Python side only.
:func:`.type_coerce` is roughly similar to :func:.`cast`, except no
"CAST" expression is rendered - the given type is only applied towards
expression typing and against received result values.
e.g.::
from sqlalchemy.types import TypeDecorator
import uuid
class AsGuid(TypeDecorator):
impl = String
def process_bind_param(self, value, dialect):
if value is not None:
return str(value)
else:
return None
def process_result_value(self, value, dialect):
if value is not None:
return uuid.UUID(value)
else:
return None
conn.execute(
select([type_coerce(mytable.c.ident, AsGuid)]).\\
where(
type_coerce(mytable.c.ident, AsGuid) ==
uuid.uuid3(uuid.NAMESPACE_URL, 'bar')
)
)
"""
if hasattr(expr, '__clause_expr__'):
return type_coerce(expr.__clause_expr__())
elif not isinstance(expr, Visitable):
if expr is None:
return null()
else:
return literal(expr, type_=type_)
else:
return _Label(None, expr, type_=type_)
def label(name, obj):
"""Return a :class:`_Label` object for the
given :class:`ColumnElement`.
A label changes the name of an element in the columns clause of a
``SELECT`` statement, typically via the ``AS`` SQL keyword.
This functionality is more conveniently available via the
:func:`label()` method on :class:`ColumnElement`.
name
label name
obj
a :class:`ColumnElement`.
"""
return _Label(name, obj)
def column(text, type_=None):
"""Return a textual column clause, as would be in the columns clause of a
``SELECT`` statement.
The object returned is an instance of
:class:`ColumnClause`, which represents the
"syntactical" portion of the schema-level
:class:`~sqlalchemy.schema.Column` object.
text
the name of the column. Quoting rules will be applied to the
clause like any other column name. For textual column
constructs that are not to be quoted, use the
:func:`literal_column` function.
type\_
an optional :class:`~sqlalchemy.types.TypeEngine` object which will
provide result-set translation for this column.
"""
return ColumnClause(text, type_=type_)
def literal_column(text, type_=None):
"""Return a textual column expression, as would be in the columns
clause of a ``SELECT`` statement.
The object returned supports further expressions in the same way as any
other column object, including comparison, math and string operations.
The type\_ parameter is important to determine proper expression behavior
(such as, '+' means string concatenation or numerical addition based on
the type).
text
the text of the expression; can be any SQL expression. Quoting rules
will not be applied. To specify a column-name expression which should
be subject to quoting rules, use the
:func:`column` function.
type\_
an optional :class:`~sqlalchemy.types.TypeEngine` object which will
provide result-set translation and additional expression semantics for
this column. If left as None the type will be NullType.
"""
return ColumnClause(text, type_=type_, is_literal=True)
def table(name, *columns):
"""Return a :class:`TableClause` object.
This is a primitive version of the :class:`~sqlalchemy.schema.Table` object,
which is a subclass of this object.
"""
return TableClause(name, *columns)
def bindparam(key, value=None, type_=None, unique=False, required=False):
"""Create a bind parameter clause with the given key.
value
a default value for this bind parameter. a bindparam with a
value is called a ``value-based bindparam``.
type\_
a sqlalchemy.types.TypeEngine object indicating the type of this
bind param, will invoke type-specific bind parameter processing
unique
if True, bind params sharing the same name will have their
underlying ``key`` modified to a uniquely generated name.
mostly useful with value-based bind params.
required
A value is required at execution time.
"""
if isinstance(key, ColumnClause):
return _BindParamClause(key.name, value, type_=key.type,
unique=unique, required=required)
else:
return _BindParamClause(key, value, type_=type_,
unique=unique, required=required)
def outparam(key, type_=None):
"""Create an 'OUT' parameter for usage in functions (stored procedures),
for databases which support them.
The ``outparam`` can be used like a regular function parameter.
The "output" value will be available from the
:class:`~sqlalchemy.engine.ResultProxy` object via its ``out_parameters``
attribute, which returns a dictionary containing the values.
"""
return _BindParamClause(
key, None, type_=type_, unique=False, isoutparam=True)
def text(text, bind=None, *args, **kwargs):
"""Create a SQL construct that is represented by a literal string.
E.g.::
t = text("SELECT * FROM users")
result = connection.execute(t)
The advantages :func:`text` provides over a plain string are
backend-neutral support for bind parameters, per-statement
execution options, as well as
bind parameter and result-column typing behavior, allowing
SQLAlchemy type constructs to play a role when executing
a statement that is specified literally.
Bind parameters are specified by name, using the format ``:name``.
E.g.::
t = text("SELECT * FROM users WHERE id=:user_id")
result = connection.execute(t, user_id=12)
To invoke SQLAlchemy typing logic for bind parameters, the
``bindparams`` list allows specification of :func:`bindparam`
constructs which specify the type for a given name::
t = text("SELECT id FROM users WHERE updated_at>:updated",
bindparams=[bindparam('updated', DateTime())]
)
Typing during result row processing is also an important concern.
Result column types
are specified using the ``typemap`` dictionary, where the keys
match the names of columns. These names are taken from what
the DBAPI returns as ``cursor.description``::
t = text("SELECT id, name FROM users",
typemap={
'id':Integer,
'name':Unicode
}
)
The :func:`text` construct is used internally for most cases when
a literal string is specified for part of a larger query, such as
within :func:`select()`, :func:`update()`,
:func:`insert()` or :func:`delete()`. In those cases, the same
bind parameter syntax is applied::
s = select([users.c.id, users.c.name]).where("id=:user_id")
result = connection.execute(s, user_id=12)
Using :func:`text` explicitly usually implies the construction
of a full, standalone statement. As such, SQLAlchemy refers
to it as an :class:`Executable` object, and it supports
the :meth:`Executable.execution_options` method. For example,
a :func:`text` construct that should be subject to "autocommit"
can be set explicitly so using the ``autocommit`` option::
t = text("EXEC my_procedural_thing()").\\
execution_options(autocommit=True)
Note that SQLAlchemy's usual "autocommit" behavior applies to
:func:`text` constructs - that is, statements which begin
with a phrase such as ``INSERT``, ``UPDATE``, ``DELETE``,
or a variety of other phrases specific to certain backends, will
be eligible for autocommit if no transaction is in progress.
:param text:
the text of the SQL statement to be created. use ``:<param>``
to specify bind parameters; they will be compiled to their
engine-specific format.
:param autocommit:
Deprecated. Use .execution_options(autocommit=<True|False>)
to set the autocommit option.
:param bind:
an optional connection or engine to be used for this text query.
:param bindparams:
a list of :func:`bindparam()` instances which can be used to define
the types and/or initial values for the bind parameters within
the textual statement; the keynames of the bindparams must match
those within the text of the statement. The types will be used
for pre-processing on bind values.
:param typemap:
a dictionary mapping the names of columns represented in the
columns clause of a ``SELECT`` statement to type objects,
which will be used to perform post-processing on columns within
the result set. This argument applies to any expression
that returns result sets.
"""
return _TextClause(text, bind=bind, *args, **kwargs)
def null():
"""Return a :class:`_Null` object, which compiles to ``NULL`` in a sql
statement.
"""
return _Null()
class _FunctionGenerator(object):
"""Generate :class:`Function` objects based on getattr calls."""
def __init__(self, **opts):
self.__names = []
self.opts = opts
def __getattr__(self, name):
# passthru __ attributes; fixes pydoc
if name.startswith('__'):
try:
return self.__dict__[name]
except KeyError:
raise AttributeError(name)
elif name.endswith('_'):
name = name[0:-1]
f = _FunctionGenerator(**self.opts)
f.__names = list(self.__names) + [name]
return f
def __call__(self, *c, **kwargs):
o = self.opts.copy()
o.update(kwargs)
if len(self.__names) == 1:
func = getattr(functions, self.__names[-1].lower(), None)
if func is not None and \
isinstance(func, type) and \
issubclass(func, Function):
return func(*c, **o)
return Function(self.__names[-1],
packagenames=self.__names[0:-1], *c, **o)
# "func" global - i.e. func.count()
func = _FunctionGenerator()
# "modifier" global - i.e. modifier.distinct
# TODO: use UnaryExpression for this instead ?
modifier = _FunctionGenerator(group=False)
class _generated_label(unicode):
"""A unicode subclass used to identify dynamically generated names."""
def _escape_for_generated(x):
if isinstance(x, _generated_label):
return x
else:
return x.replace('%', '%%')
def _clone(element):
return element._clone()
def _expand_cloned(elements):
"""expand the given set of ClauseElements to be the set of all 'cloned'
predecessors.
"""
return itertools.chain(*[x._cloned_set for x in elements])
def _select_iterables(elements):
"""expand tables into individual columns in the
given list of column expressions.
"""
return itertools.chain(*[c._select_iterable for c in elements])
def _cloned_intersection(a, b):
"""return the intersection of sets a and b, counting
any overlap between 'cloned' predecessors.
The returned set is in terms of the enties present within 'a'.
"""
all_overlap = set(_expand_cloned(a)).intersection(_expand_cloned(b))
return set(elem for elem in a
if all_overlap.intersection(elem._cloned_set))
def _is_literal(element):
return not isinstance(element, Visitable) and \
not hasattr(element, '__clause_element__')
def _from_objects(*elements):
return itertools.chain(*[element._from_objects for element in elements])
def _labeled(element):
if not hasattr(element, 'name'):
return element.label(None)
else:
return element
def _column_as_key(element):
if isinstance(element, basestring):
return element
if hasattr(element, '__clause_element__'):
element = element.__clause_element__()
return element.key
def _literal_as_text(element):
if hasattr(element, '__clause_element__'):
return element.__clause_element__()
elif not isinstance(element, Visitable):
return _TextClause(unicode(element))
else:
return element
def _clause_element_as_expr(element):
if hasattr(element, '__clause_element__'):
return element.__clause_element__()
else:
return element
def _literal_as_column(element):
if hasattr(element, '__clause_element__'):
return element.__clause_element__()
elif not isinstance(element, Visitable):
return literal_column(str(element))
else:
return element
def _literal_as_binds(element, name=None, type_=None):
if hasattr(element, '__clause_element__'):
return element.__clause_element__()
elif not isinstance(element, Visitable):
if element is None:
return null()
else:
return _BindParamClause(name, element, type_=type_, unique=True)
else:
return element
def _type_from_args(args):
for a in args:
if not isinstance(a.type, sqltypes.NullType):
return a.type
else:
return sqltypes.NullType
def _no_literals(element):
if hasattr(element, '__clause_element__'):
return element.__clause_element__()
elif not isinstance(element, Visitable):
raise exc.ArgumentError("Ambiguous literal: %r. Use the 'text()' "
"function to indicate a SQL expression "
"literal, or 'literal()' to indicate a "
"bound value." % element)
else:
return element
def _only_column_elements(element, name):
if hasattr(element, '__clause_element__'):
element = element.__clause_element__()
if not isinstance(element, ColumnElement):
raise exc.ArgumentError("Column-based expression object expected for argument '%s'; "
"got: '%s', type %s" % (name, element, type(element)))
return element
def _corresponding_column_or_error(fromclause, column,
require_embedded=False):
c = fromclause.corresponding_column(column,
require_embedded=require_embedded)
if c is None:
raise exc.InvalidRequestError(
"Given column '%s', attached to table '%s', "
"failed to locate a corresponding column from table '%s'"
%
(column,
getattr(column, 'table', None),fromclause.description)
)
return c
@util.decorator
def _generative(fn, *args, **kw):
"""Mark a method as generative."""
self = args[0]._generate()
fn(self, *args[1:], **kw)
return self
def is_column(col):
"""True if ``col`` is an instance of :class:`ColumnElement`."""
return isinstance(col, ColumnElement)
class ClauseElement(Visitable):
"""Base class for elements of a programmatically constructed SQL
expression.
"""
__visit_name__ = 'clause'
_annotations = {}
supports_execution = False
_from_objects = []
_bind = None
def _clone(self):
"""Create a shallow copy of this ClauseElement.
This method may be used by a generative API. Its also used as
part of the "deep" copy afforded by a traversal that combines
the _copy_internals() method.
"""
c = self.__class__.__new__(self.__class__)
c.__dict__ = self.__dict__.copy()
c.__dict__.pop('_cloned_set', None)
# this is a marker that helps to "equate" clauses to each other
# when a Select returns its list of FROM clauses. the cloning
# process leaves around a lot of remnants of the previous clause
# typically in the form of column expressions still attached to the
# old table.
c._is_clone_of = self
return c
@property
def _constructor(self):
"""return the 'constructor' for this ClauseElement.
This is for the purposes for creating a new object of
this type. Usually, its just the element's __class__.
However, the "Annotated" version of the object overrides
to return the class of its proxied element.
"""
return self.__class__
@util.memoized_property
def _cloned_set(self):
"""Return the set consisting all cloned anscestors of this
ClauseElement.
Includes this ClauseElement. This accessor tends to be used for
FromClause objects to identify 'equivalent' FROM clauses, regardless
of transformative operations.
"""
s = util.column_set()
f = self
while f is not None:
s.add(f)
f = getattr(f, '_is_clone_of', None)
return s
def __getstate__(self):
d = self.__dict__.copy()
d.pop('_is_clone_of', None)
return d
if util.jython:
def __hash__(self):
"""Return a distinct hash code.
ClauseElements may have special equality comparisons which
makes us rely on them having unique hash codes for use in
hash-based collections. Stock __hash__ doesn't guarantee
unique values on platforms with moving GCs.
"""
return id(self)
def _annotate(self, values):
"""return a copy of this ClauseElement with the given annotations
dictionary.
"""
return sqlutil.Annotated(self, values)
def _deannotate(self):
"""return a copy of this ClauseElement with an empty annotations
dictionary.
"""
return self._clone()
def unique_params(self, *optionaldict, **kwargs):
"""Return a copy with :func:`bindparam()` elments replaced.
Same functionality as ``params()``, except adds `unique=True`
to affected bind parameters so that multiple statements can be
used.
"""
return self._params(True, optionaldict, kwargs)
def params(self, *optionaldict, **kwargs):
"""Return a copy with :func:`bindparam()` elments replaced.
Returns a copy of this ClauseElement with :func:`bindparam()`
elements replaced with values taken from the given dictionary::
>>> clause = column('x') + bindparam('foo')
>>> print clause.compile().params
{'foo':None}
>>> print clause.params({'foo':7}).compile().params
{'foo':7}
"""
return self._params(False, optionaldict, kwargs)
def _params(self, unique, optionaldict, kwargs):
if len(optionaldict) == 1:
kwargs.update(optionaldict[0])
elif len(optionaldict) > 1:
raise exc.ArgumentError(
"params() takes zero or one positional dictionary argument")
def visit_bindparam(bind):
if bind.key in kwargs:
bind.value = kwargs[bind.key]
if unique:
bind._convert_to_unique()
return cloned_traverse(self, {}, {'bindparam':visit_bindparam})
def compare(self, other, **kw):
"""Compare this ClauseElement to the given ClauseElement.
Subclasses should override the default behavior, which is a
straight identity comparison.
\**kw are arguments consumed by subclass compare() methods and
may be used to modify the criteria for comparison.
(see :class:`ColumnElement`)
"""
return self is other
def _copy_internals(self, clone=_clone):
"""Reassign internal elements to be clones of themselves.
Called during a copy-and-traverse operation on newly
shallow-copied elements to create a deep copy.
"""
pass
def get_children(self, **kwargs):
"""Return immediate child elements of this :class:`ClauseElement`.
This is used for visit traversal.
\**kwargs may contain flags that change the collection that is
returned, for example to return a subset of items in order to
cut down on larger traversals, or to return child items from a
different context (such as schema-level collections instead of
clause-level).
"""
return []
def self_group(self, against=None):
"""Apply a 'grouping' to this :class:`.ClauseElement`.
This method is overridden by subclasses to return a
"grouping" construct, i.e. parenthesis. In particular
it's used by "binary" expressions to provide a grouping
around themselves when placed into a larger expression,
as well as by :func:`.select` constructs when placed into
the FROM clause of another :func:`.select`. (Note that
subqueries should be normally created using the
:func:`.Select.alias` method, as many platforms require
nested SELECT statements to be named).
As expressions are composed together, the application of
:meth:`self_group` is automatic - end-user code should never
need to use this method directly. Note that SQLAlchemy's
clause constructs take operator precedence into account -
so parenthesis might not be needed, for example, in
an expression like ``x OR (y AND z)`` - AND takes precedence
over OR.
The base :meth:`self_group` method of :class:`.ClauseElement`
just returns self.
"""
return self
# TODO: remove .bind as a method from the root ClauseElement.
# we should only be deriving binds from FromClause elements
# and certain SchemaItem subclasses.
# the "search_for_bind" functionality can still be used by
# execute(), however.
@property
def bind(self):
"""Returns the Engine or Connection to which this ClauseElement is
bound, or None if none found.
"""
if self._bind is not None:
return self._bind
for f in _from_objects(self):
if f is self:
continue
engine = f.bind
if engine is not None:
return engine
else:
return None
@util.pending_deprecation('0.7',
'Only SQL expressions which subclass '
':class:`.Executable` may provide the '
':func:`.execute` method.')
def execute(self, *multiparams, **params):
"""Compile and execute this :class:`ClauseElement`.
"""
e = self.bind
if e is None:
label = getattr(self, 'description', self.__class__.__name__)
msg = ('This %s is not bound and does not support direct '
'execution. Supply this statement to a Connection or '
'Engine for execution. Or, assign a bind to the statement '
'or the Metadata of its underlying tables to enable '
'implicit execution via this method.' % label)
raise exc.UnboundExecutionError(msg)
return e._execute_clauseelement(self, multiparams, params)
@util.pending_deprecation('0.7',
'Only SQL expressions which subclass '
':class:`.Executable` may provide the '
':func:`.scalar` method.')
def scalar(self, *multiparams, **params):
"""Compile and execute this :class:`ClauseElement`, returning
the result's scalar representation.
"""
return self.execute(*multiparams, **params).scalar()
def compile(self, bind=None, dialect=None, **kw):
"""Compile this SQL expression.
The return value is a :class:`~sqlalchemy.engine.Compiled` object.
Calling ``str()`` or ``unicode()`` on the returned value will yield a
string representation of the result. The
:class:`~sqlalchemy.engine.Compiled` object also can return a
dictionary of bind parameter names and values
using the ``params`` accessor.
:param bind: An ``Engine`` or ``Connection`` from which a
``Compiled`` will be acquired. This argument takes precedence over
this :class:`ClauseElement`'s bound engine, if any.
:param column_keys: Used for INSERT and UPDATE statements, a list of
column names which should be present in the VALUES clause of the
compiled statement. If ``None``, all columns from the target table
object are rendered.
:param dialect: A ``Dialect`` instance frmo which a ``Compiled``
will be acquired. This argument takes precedence over the `bind`
argument as well as this :class:`ClauseElement`'s bound engine, if
any.
:param inline: Used for INSERT statements, for a dialect which does
not support inline retrieval of newly generated primary key
columns, will force the expression used to create the new primary
key value to be rendered inline within the INSERT statement's
VALUES clause. This typically refers to Sequence execution but may
also refer to any server-side default generation function
associated with a primary key `Column`.
"""
if not dialect:
if bind:
dialect = bind.dialect
elif self.bind:
dialect = self.bind.dialect
bind = self.bind
else:
dialect = default.DefaultDialect()
compiler = self._compiler(dialect, bind=bind, **kw)
compiler.compile()
return compiler
def _compiler(self, dialect, **kw):
"""Return a compiler appropriate for this ClauseElement, given a
Dialect."""
return dialect.statement_compiler(dialect, self, **kw)
def __str__(self):
# Py3K
#return unicode(self.compile())
# Py2K
return unicode(self.compile()).encode('ascii', 'backslashreplace')
# end Py2K
def __and__(self, other):
return and_(self, other)
def __or__(self, other):
return or_(self, other)
def __invert__(self):
return self._negate()
def __nonzero__(self):
raise TypeError("Boolean value of this clause is not defined")
def _negate(self):
if hasattr(self, 'negation_clause'):
return self.negation_clause
else:
return _UnaryExpression(
self.self_group(against=operators.inv),
operator=operators.inv,
negate=None)
def __repr__(self):
friendly = getattr(self, 'description', None)
if friendly is None:
return object.__repr__(self)
else:
return '<%s.%s at 0x%x; %s>' % (
self.__module__, self.__class__.__name__, id(self), friendly)
class _Immutable(object):
"""mark a ClauseElement as 'immutable' when expressions are cloned."""
def unique_params(self, *optionaldict, **kwargs):
raise NotImplementedError("Immutable objects do not support copying")
def params(self, *optionaldict, **kwargs):
raise NotImplementedError("Immutable objects do not support copying")
def _clone(self):
return self
class Operators(object):
def __and__(self, other):
return self.operate(operators.and_, other)
def __or__(self, other):
return self.operate(operators.or_, other)
def __invert__(self):
return self.operate(operators.inv)
def op(self, opstring):
def op(b):
return self.operate(operators.op, opstring, b)
return op
def operate(self, op, *other, **kwargs):
raise NotImplementedError(str(op))
def reverse_operate(self, op, other, **kwargs):
raise NotImplementedError(str(op))
class ColumnOperators(Operators):
"""Defines comparison and math operations."""
timetuple = None
"""Hack, allows datetime objects to be compared on the LHS."""
def __lt__(self, other):
return self.operate(operators.lt, other)
def __le__(self, other):
return self.operate(operators.le, other)
__hash__ = Operators.__hash__
def __eq__(self, other):
return self.operate(operators.eq, other)
def __ne__(self, other):
return self.operate(operators.ne, other)
def __gt__(self, other):
return self.operate(operators.gt, other)
def __ge__(self, other):
return self.operate(operators.ge, other)
def __neg__(self):
return self.operate(operators.neg)
def concat(self, other):
return self.operate(operators.concat_op, other)
def like(self, other, escape=None):
return self.operate(operators.like_op, other, escape=escape)
def ilike(self, other, escape=None):
return self.operate(operators.ilike_op, other, escape=escape)
def in_(self, other):
return self.operate(operators.in_op, other)
def startswith(self, other, **kwargs):
return self.operate(operators.startswith_op, other, **kwargs)
def endswith(self, other, **kwargs):
return self.operate(operators.endswith_op, other, **kwargs)
def contains(self, other, **kwargs):
return self.operate(operators.contains_op, other, **kwargs)
def match(self, other, **kwargs):
return self.operate(operators.match_op, other, **kwargs)
def desc(self):
return self.operate(operators.desc_op)
def asc(self):
return self.operate(operators.asc_op)
def collate(self, collation):
return self.operate(operators.collate, collation)
def __radd__(self, other):
return self.reverse_operate(operators.add, other)
def __rsub__(self, other):
return self.reverse_operate(operators.sub, other)
def __rmul__(self, other):
return self.reverse_operate(operators.mul, other)
def __rdiv__(self, other):
return self.reverse_operate(operators.div, other)
def between(self, cleft, cright):
return self.operate(operators.between_op, cleft, cright)
def distinct(self):
return self.operate(operators.distinct_op)
def __add__(self, other):
return self.operate(operators.add, other)
def __sub__(self, other):
return self.operate(operators.sub, other)
def __mul__(self, other):
return self.operate(operators.mul, other)
def __div__(self, other):
return self.operate(operators.div, other)
def __mod__(self, other):
return self.operate(operators.mod, other)
def __truediv__(self, other):
return self.operate(operators.truediv, other)
def __rtruediv__(self, other):
return self.reverse_operate(operators.truediv, other)
class _CompareMixin(ColumnOperators):
"""Defines comparison and math operations for :class:`ClauseElement`
instances."""
def __compare(self, op, obj, negate=None, reverse=False,
**kwargs
):
if obj is None or isinstance(obj, _Null):
if op == operators.eq:
return _BinaryExpression(self, null(), operators.is_,
negate=operators.isnot)
elif op == operators.ne:
return _BinaryExpression(self, null(), operators.isnot,
negate=operators.is_)
else:
raise exc.ArgumentError("Only '='/'!=' operators can "
"be used with NULL")
else:
obj = self._check_literal(op, obj)
if reverse:
return _BinaryExpression(obj,
self,
op,
type_=sqltypes.BOOLEANTYPE,
negate=negate, modifiers=kwargs)
else:
return _BinaryExpression(self,
obj,
op,
type_=sqltypes.BOOLEANTYPE,
negate=negate, modifiers=kwargs)
def __operate(self, op, obj, reverse=False):
obj = self._check_literal(op, obj)
if reverse:
left, right = obj, self
else:
left, right = self, obj
if left.type is None:
op, result_type = sqltypes.NULLTYPE._adapt_expression(op,
right.type)
elif right.type is None:
op, result_type = left.type._adapt_expression(op,
sqltypes.NULLTYPE)
else:
op, result_type = left.type._adapt_expression(op,
right.type)
return _BinaryExpression(left, right, op, type_=result_type)
# a mapping of operators with the method they use, along with their negated
# operator for comparison operators
operators = {
operators.add : (__operate,),
operators.mul : (__operate,),
operators.sub : (__operate,),
# Py2K
operators.div : (__operate,),
# end Py2K
operators.mod : (__operate,),
operators.truediv : (__operate,),
operators.lt : (__compare, operators.ge),
operators.le : (__compare, operators.gt),
operators.ne : (__compare, operators.eq),
operators.gt : (__compare, operators.le),
operators.ge : (__compare, operators.lt),
operators.eq : (__compare, operators.ne),
operators.like_op : (__compare, operators.notlike_op),
operators.ilike_op : (__compare, operators.notilike_op),
}
def operate(self, op, *other, **kwargs):
o = _CompareMixin.operators[op]
return o[0](self, op, other[0], *o[1:], **kwargs)
def reverse_operate(self, op, other, **kwargs):
o = _CompareMixin.operators[op]
return o[0](self, op, other, reverse=True, *o[1:], **kwargs)
def in_(self, other):
"""Compare this element to the given element or collection using IN."""
return self._in_impl(operators.in_op, operators.notin_op, other)
def _in_impl(self, op, negate_op, seq_or_selectable):
seq_or_selectable = _clause_element_as_expr(seq_or_selectable)
if isinstance(seq_or_selectable, _ScalarSelect):
return self.__compare(op, seq_or_selectable,
negate=negate_op)
elif isinstance(seq_or_selectable, _SelectBaseMixin):
# TODO: if we ever want to support (x, y, z) IN (select x,
# y, z from table), we would need a multi-column version of
# as_scalar() to produce a multi- column selectable that
# does not export itself as a FROM clause
return self.__compare(op, seq_or_selectable.as_scalar(),
negate=negate_op)
elif isinstance(seq_or_selectable, (Selectable, _TextClause)):
return self.__compare(op, seq_or_selectable,
negate=negate_op)
# Handle non selectable arguments as sequences
args = []
for o in seq_or_selectable:
if not _is_literal(o):
if not isinstance(o, _CompareMixin):
raise exc.InvalidRequestError('in() function accept'
's either a list of non-selectable values, '
'or a selectable: %r' % o)
else:
o = self._bind_param(op, o)
args.append(o)
if len(args) == 0:
# Special case handling for empty IN's, behave like
# comparison against zero row selectable. We use != to
# build the contradiction as it handles NULL values
# appropriately, i.e. "not (x IN ())" should not return NULL
# values for x.
util.warn('The IN-predicate on "%s" was invoked with an '
'empty sequence. This results in a '
'contradiction, which nonetheless can be '
'expensive to evaluate. Consider alternative '
'strategies for improved performance.' % self)
return self != self
return self.__compare(op,
ClauseList(*args).self_group(against=op),
negate=negate_op)
def __neg__(self):
return _UnaryExpression(self, operator=operators.neg)
def startswith(self, other, escape=None):
"""Produce the clause ``LIKE '<other>%'``"""
# use __radd__ to force string concat behavior
return self.__compare(
operators.like_op,
literal_column("'%'", type_=sqltypes.String).__radd__(
self._check_literal(operators.like_op, other)
),
escape=escape)
def endswith(self, other, escape=None):
"""Produce the clause ``LIKE '%<other>'``"""
return self.__compare(
operators.like_op,
literal_column("'%'", type_=sqltypes.String) +
self._check_literal(operators.like_op, other),
escape=escape)
def contains(self, other, escape=None):
"""Produce the clause ``LIKE '%<other>%'``"""
return self.__compare(
operators.like_op,
literal_column("'%'", type_=sqltypes.String) +
self._check_literal(operators.like_op, other) +
literal_column("'%'", type_=sqltypes.String),
escape=escape)
def match(self, other):
"""Produce a MATCH clause, i.e. ``MATCH '<other>'``
The allowed contents of ``other`` are database backend specific.
"""
return self.__compare(operators.match_op,
self._check_literal(operators.match_op,
other))
def label(self, name):
"""Produce a column label, i.e. ``<columnname> AS <name>``.
This is a shortcut to the :func:`~.expression.label` function.
if 'name' is None, an anonymous label name will be generated.
"""
return _Label(name, self, self.type)
def desc(self):
"""Produce a DESC clause, i.e. ``<columnname> DESC``"""
return desc(self)
def asc(self):
"""Produce a ASC clause, i.e. ``<columnname> ASC``"""
return asc(self)
def distinct(self):
"""Produce a DISTINCT clause, i.e. ``DISTINCT <columnname>``"""
return _UnaryExpression(self, operator=operators.distinct_op,
type_=self.type)
def between(self, cleft, cright):
"""Produce a BETWEEN clause, i.e. ``<column> BETWEEN <cleft> AND
<cright>``"""
return _BinaryExpression(
self,
ClauseList(
self._check_literal(operators.and_, cleft),
self._check_literal(operators.and_, cright),
operator=operators.and_,
group=False),
operators.between_op)
def collate(self, collation):
"""Produce a COLLATE clause, i.e. ``<column> COLLATE utf8_bin``"""
return collate(self, collation)
def op(self, operator):
"""produce a generic operator function.
e.g.::
somecolumn.op("*")(5)
produces::
somecolumn * 5
:param operator: a string which will be output as the infix operator
between this :class:`ClauseElement` and the expression passed to the
generated function.
This function can also be used to make bitwise operators explicit. For
example::
somecolumn.op('&')(0xff)
is a bitwise AND of the value in somecolumn.
"""
return lambda other: self.__operate(operator, other)
def _bind_param(self, operator, obj):
return _BindParamClause(None, obj,
_compared_to_operator=operator,
_compared_to_type=self.type, unique=True)
def _check_literal(self, operator, other):
if isinstance(other, _BindParamClause) and \
isinstance(other.type, sqltypes.NullType):
# TODO: perhaps we should not mutate the incoming bindparam()
# here and instead make a copy of it. this might
# be the only place that we're mutating an incoming construct.
other.type = self.type
return other
elif hasattr(other, '__clause_element__'):
return other.__clause_element__()
elif not isinstance(other, ClauseElement):
return self._bind_param(operator, other)
elif isinstance(other, (_SelectBaseMixin, Alias)):
return other.as_scalar()
else:
return other
class ColumnElement(ClauseElement, _CompareMixin):
"""Represent an element that is usable within the "column clause" portion
of a ``SELECT`` statement.
This includes columns associated with tables, aliases, and
subqueries, expressions, function calls, SQL keywords such as
``NULL``, literals, etc. :class:`ColumnElement` is the ultimate base
class for all such elements.
:class:`ColumnElement` supports the ability to be a *proxy* element,
which indicates that the :class:`ColumnElement` may be associated with
a :class:`Selectable` which was derived from another :class:`Selectable`.
An example of a "derived" :class:`Selectable` is an :class:`Alias` of a
:class:`~sqlalchemy.schema.Table`.
A :class:`ColumnElement`, by subclassing the :class:`_CompareMixin` mixin
class, provides the ability to generate new :class:`ClauseElement`
objects using Python expressions. See the :class:`_CompareMixin`
docstring for more details.
"""
__visit_name__ = 'column'
primary_key = False
foreign_keys = []
quote = None
_label = None
@property
def _select_iterable(self):
return (self, )
@util.memoized_property
def base_columns(self):
return util.column_set(c for c in self.proxy_set
if not hasattr(c, 'proxies'))
@util.memoized_property
def proxy_set(self):
s = util.column_set([self])
if hasattr(self, 'proxies'):
for c in self.proxies:
s.update(c.proxy_set)
return s
def shares_lineage(self, othercolumn):
"""Return True if the given :class:`ColumnElement`
has a common ancestor to this :class:`ColumnElement`."""
return bool(self.proxy_set.intersection(othercolumn.proxy_set))
def _make_proxy(self, selectable, name=None):
"""Create a new :class:`ColumnElement` representing this
:class:`ColumnElement` as it appears in the select list of a
descending selectable.
"""
if name is None:
name = self.anon_label
# TODO: may want to change this to anon_label,
# or some value that is more useful than the
# compiled form of the expression
key = str(self)
else:
key = name
co = ColumnClause(name, selectable, type_=getattr(self,
'type', None))
co.proxies = [self]
selectable.columns[key] = co
return co
def compare(self, other, use_proxies=False, equivalents=None, **kw):
"""Compare this ColumnElement to another.
Special arguments understood:
:param use_proxies: when True, consider two columns that
share a common base column as equivalent (i.e. shares_lineage())
:param equivalents: a dictionary of columns as keys mapped to sets
of columns. If the given "other" column is present in this
dictionary, if any of the columns in the correponding set() pass the
comparison test, the result is True. This is used to expand the
comparison to other columns that may be known to be equivalent to
this one via foreign key or other criterion.
"""
to_compare = (other, )
if equivalents and other in equivalents:
to_compare = equivalents[other].union(to_compare)
for oth in to_compare:
if use_proxies and self.shares_lineage(oth):
return True
elif oth is self:
return True
else:
return False
@util.memoized_property
def anon_label(self):
"""provides a constant 'anonymous label' for this ColumnElement.
This is a label() expression which will be named at compile time.
The same label() is returned each time anon_label is called so
that expressions can reference anon_label multiple times, producing
the same label name at compile time.
the compiler uses this function automatically at compile time
for expressions that are known to be 'unnamed' like binary
expressions and function calls.
"""
return _generated_label('%%(%d %s)s' % (id(self), getattr(self,
'name', 'anon')))
class ColumnCollection(util.OrderedProperties):
"""An ordered dictionary that stores a list of ColumnElement
instances.
Overrides the ``__eq__()`` method to produce SQL clauses between
sets of correlated columns.
"""
def __init__(self, *cols):
super(ColumnCollection, self).__init__()
self.update((c.key, c) for c in cols)
def __str__(self):
return repr([str(c) for c in self])
def replace(self, column):
"""add the given column to this collection, removing unaliased
versions of this column as well as existing columns with the
same key.
e.g.::
t = Table('sometable', metadata, Column('col1', Integer))
t.columns.replace(Column('col1', Integer, key='columnone'))
will remove the original 'col1' from the collection, and add
the new column under the name 'columnname'.
Used by schema.Column to override columns during table reflection.
"""
if column.name in self and column.key != column.name:
other = self[column.name]
if other.name == other.key:
del self[other.name]
util.OrderedProperties.__setitem__(self, column.key, column)
def add(self, column):
"""Add a column to this collection.
The key attribute of the column will be used as the hash key
for this dictionary.
"""
self[column.key] = column
def __setitem__(self, key, value):
if key in self:
# this warning is primarily to catch select() statements
# which have conflicting column names in their exported
# columns collection
existing = self[key]
if not existing.shares_lineage(value):
util.warn('Column %r on table %r being replaced by '
'another column with the same key. Consider '
'use_labels for select() statements.' % (key,
getattr(existing, 'table', None)))
util.OrderedProperties.__setitem__(self, key, value)
def remove(self, column):
del self[column.key]
def extend(self, iter):
for c in iter:
self.add(c)
__hash__ = None
def __eq__(self, other):
l = []
for c in other:
for local in self:
if c.shares_lineage(local):
l.append(c==local)
return and_(*l)
def __contains__(self, other):
if not isinstance(other, basestring):
raise exc.ArgumentError("__contains__ requires a string argument")
return util.OrderedProperties.__contains__(self, other)
def contains_column(self, col):
# have to use a Set here, because it will compare the identity
# of the column, not just using "==" for comparison which will
# always return a "True" value (i.e. a BinaryClause...)
return col in util.column_set(self)
class ColumnSet(util.ordered_column_set):
def contains_column(self, col):
return col in self
def extend(self, cols):
for col in cols:
self.add(col)
def __add__(self, other):
return list(self) + list(other)
def __eq__(self, other):
l = []
for c in other:
for local in self:
if c.shares_lineage(local):
l.append(c==local)
return and_(*l)
def __hash__(self):
return hash(tuple(x for x in self))
class Selectable(ClauseElement):
"""mark a class as being selectable"""
__visit_name__ = 'selectable'
class FromClause(Selectable):
"""Represent an element that can be used within the ``FROM``
clause of a ``SELECT`` statement.
"""
__visit_name__ = 'fromclause'
named_with_column = False
_hide_froms = []
quote = None
schema = None
def count(self, whereclause=None, **params):
"""return a SELECT COUNT generated against this
:class:`FromClause`."""
if self.primary_key:
col = list(self.primary_key)[0]
else:
col = list(self.columns)[0]
return select(
[func.count(col).label('tbl_row_count')],
whereclause,
from_obj=[self],
**params)
def select(self, whereclause=None, **params):
"""return a SELECT of this :class:`FromClause`."""
return select([self], whereclause, **params)
def join(self, right, onclause=None, isouter=False):
"""return a join of this :class:`FromClause` against another
:class:`FromClause`."""
return Join(self, right, onclause, isouter)
def outerjoin(self, right, onclause=None):
"""return an outer join of this :class:`FromClause` against another
:class:`FromClause`."""
return Join(self, right, onclause, True)
def alias(self, name=None):
"""return an alias of this :class:`FromClause`.
For table objects, this has the effect of the table being rendered
as ``tablename AS aliasname`` in a SELECT statement.
For select objects, the effect is that of creating a named
subquery, i.e. ``(select ...) AS aliasname``.
The :func:`alias()` method is the general way to create
a "subquery" out of an existing SELECT.
The ``name`` parameter is optional, and if left blank an
"anonymous" name will be generated at compile time, guaranteed
to be unique against other anonymous constructs used in the
same statement.
"""
return Alias(self, name)
def is_derived_from(self, fromclause):
"""Return True if this FromClause is 'derived' from the given
FromClause.
An example would be an Alias of a Table is derived from that Table.
"""
return fromclause in self._cloned_set
def replace_selectable(self, old, alias):
"""replace all occurences of FromClause 'old' with the given Alias
object, returning a copy of this :class:`FromClause`.
"""
return sqlutil.ClauseAdapter(alias).traverse(self)
def correspond_on_equivalents(self, column, equivalents):
"""Return corresponding_column for the given column, or if None
search for a match in the given dictionary.
"""
col = self.corresponding_column(column, require_embedded=True)
if col is None and col in equivalents:
for equiv in equivalents[col]:
nc = self.corresponding_column(equiv, require_embedded=True)
if nc:
return nc
return col
def corresponding_column(self, column, require_embedded=False):
"""Given a :class:`ColumnElement`, return the exported
:class:`ColumnElement` object from this :class:`Selectable`
which corresponds to that original
:class:`~sqlalchemy.schema.Column` via a common anscestor
column.
:param column: the target :class:`ColumnElement` to be matched
:param require_embedded: only return corresponding columns for
the given :class:`ColumnElement`, if the given
:class:`ColumnElement` is actually present within a sub-element
of this :class:`FromClause`. Normally the column will match if
it merely shares a common anscestor with one of the exported
columns of this :class:`FromClause`.
"""
# dont dig around if the column is locally present
if self.c.contains_column(column):
return column
col, intersect = None, None
target_set = column.proxy_set
cols = self.c
for c in cols:
i = target_set.intersection(itertools.chain(*[p._cloned_set
for p in c.proxy_set]))
if i and (not require_embedded
or c.proxy_set.issuperset(target_set)):
if col is None:
# no corresponding column yet, pick this one.
col, intersect = c, i
elif len(i) > len(intersect):
# 'c' has a larger field of correspondence than
# 'col'. i.e. selectable.c.a1_x->a1.c.x->table.c.x
# matches a1.c.x->table.c.x better than
# selectable.c.x->table.c.x does.
col, intersect = c, i
elif i == intersect:
# they have the same field of correspondence. see
# which proxy_set has fewer columns in it, which
# indicates a closer relationship with the root
# column. Also take into account the "weight"
# attribute which CompoundSelect() uses to give
# higher precedence to columns based on vertical
# position in the compound statement, and discard
# columns that have no reference to the target
# column (also occurs with CompoundSelect)
col_distance = util.reduce(operator.add,
[sc._annotations.get('weight', 1) for sc in
col.proxy_set if sc.shares_lineage(column)])
c_distance = util.reduce(operator.add,
[sc._annotations.get('weight', 1) for sc in
c.proxy_set if sc.shares_lineage(column)])
if c_distance < col_distance:
col, intersect = c, i
return col
@property
def description(self):
"""a brief description of this FromClause.
Used primarily for error message formatting.
"""
return getattr(self, 'name', self.__class__.__name__ + " object")
def _reset_exported(self):
"""delete memoized collections when a FromClause is cloned."""
for attr in '_columns', '_primary_key', '_foreign_keys', \
'locate_all_froms':
self.__dict__.pop(attr, None)
@util.memoized_property
def _columns(self):
"""Return the collection of Column objects contained by this
FromClause."""
self._export_columns()
return self._columns
@util.memoized_property
def _primary_key(self):
"""Return the collection of Column objects which comprise the
primary key of this FromClause."""
self._export_columns()
return self._primary_key
@util.memoized_property
def _foreign_keys(self):
"""Return the collection of ForeignKey objects which this
FromClause references."""
self._export_columns()
return self._foreign_keys
columns = property(attrgetter('_columns'), doc=_columns.__doc__)
primary_key = property(attrgetter('_primary_key'),
doc=_primary_key.__doc__)
foreign_keys = property(attrgetter('_foreign_keys'),
doc=_foreign_keys.__doc__)
# synonyms for 'columns'
c = _select_iterable = property(attrgetter('columns'),
doc=_columns.__doc__)
def _export_columns(self):
"""Initialize column collections."""
self._columns = ColumnCollection()
self._primary_key = ColumnSet()
self._foreign_keys = set()
self._populate_column_collection()
def _populate_column_collection(self):
pass
class _BindParamClause(ColumnElement):
"""Represent a bind parameter.
Public constructor is the :func:`bindparam()` function.
"""
__visit_name__ = 'bindparam'
quote = None
def __init__(self, key, value, type_=None, unique=False,
isoutparam=False, required=False,
_compared_to_operator=None,
_compared_to_type=None):
"""Construct a _BindParamClause.
:param key:
the key for this bind param. Will be used in the generated
SQL statement for dialects that use named parameters. This
value may be modified when part of a compilation operation,
if other :class:`_BindParamClause` objects exist with the same
key, or if its length is too long and truncation is
required.
:param value:
Initial value for this bind param. This value may be
overridden by the dictionary of parameters sent to statement
compilation/execution.
:param type\_:
A ``TypeEngine`` object that will be used to pre-process the
value corresponding to this :class:`_BindParamClause` at
execution time.
:param unique:
if True, the key name of this BindParamClause will be
modified if another :class:`_BindParamClause` of the same name
already has been located within the containing
:class:`ClauseElement`.
:param required:
a value is required at execution time.
:param isoutparam:
if True, the parameter should be treated like a stored procedure
"OUT" parameter.
"""
if unique:
self.key = _generated_label('%%(%d %s)s' % (id(self), key
or 'param'))
else:
self.key = key or _generated_label('%%(%d param)s'
% id(self))
self._orig_key = key or 'param'
self.unique = unique
self.value = value
self.isoutparam = isoutparam
self.required = required
if type_ is None:
if _compared_to_type is not None:
self.type = \
_compared_to_type._coerce_compared_value(
_compared_to_operator, value)
else:
self.type = sqltypes.type_map.get(type(value),
sqltypes.NULLTYPE)
elif isinstance(type_, type):
self.type = type_()
else:
self.type = type_
def _clone(self):
c = ClauseElement._clone(self)
if self.unique:
c.key = _generated_label('%%(%d %s)s' % (id(c), c._orig_key
or 'param'))
return c
def _convert_to_unique(self):
if not self.unique:
self.unique = True
self.key = _generated_label('%%(%d %s)s' % (id(self),
self._orig_key or 'param'))
def bind_processor(self, dialect):
return self.type.dialect_impl(dialect).bind_processor(dialect)
def compare(self, other, **kw):
"""Compare this :class:`_BindParamClause` to the given
clause."""
return isinstance(other, _BindParamClause) \
and self.type._compare_type_affinity(other.type) \
and self.value == other.value
def __getstate__(self):
"""execute a deferred value for serialization purposes."""
d = self.__dict__.copy()
v = self.value
if util.callable(v):
v = v()
d['value'] = v
return d
def __repr__(self):
return '_BindParamClause(%r, %r, type_=%r)' % (self.key,
self.value, self.type)
class _TypeClause(ClauseElement):
"""Handle a type keyword in a SQL statement.
Used by the ``Case`` statement.
"""
__visit_name__ = 'typeclause'
def __init__(self, type):
self.type = type
class _Generative(object):
"""Allow a ClauseElement to generate itself via the
@_generative decorator.
"""
def _generate(self):
s = self.__class__.__new__(self.__class__)
s.__dict__ = self.__dict__.copy()
return s
class Executable(_Generative):
"""Mark a ClauseElement as supporting execution.
:class:`Executable` is a superclass for all "statement" types
of objects, including :func:`select`, :func:`delete`, :func:`update`,
:func:`insert`, :func:`text`.
"""
supports_execution = True
_execution_options = util.frozendict()
@_generative
def execution_options(self, **kw):
""" Set non-SQL options for the statement which take effect during
execution.
Current options include:
* autocommit - when True, a COMMIT will be invoked after execution
when executed in 'autocommit' mode, i.e. when an explicit
transaction is not begun on the connection. Note that DBAPI
connections by default are always in a transaction - SQLAlchemy uses
rules applied to different kinds of statements to determine if
COMMIT will be invoked in order to provide its "autocommit" feature.
Typically, all INSERT/UPDATE/DELETE statements as well as
CREATE/DROP statements have autocommit behavior enabled; SELECT
constructs do not. Use this option when invoking a SELECT or other
specific SQL construct where COMMIT is desired (typically when
calling stored procedures and such).
* stream_results - indicate to the dialect that results should be
"streamed" and not pre-buffered, if possible. This is a limitation
of many DBAPIs. The flag is currently understood only by the
psycopg2 dialect.
* compiled_cache - a dictionary where :class:`Compiled` objects
will be cached when the :class:`Connection` compiles a clause
expression into a dialect- and parameter-specific
:class:`Compiled` object. It is the user's responsibility to
manage the size of this dictionary, which will have keys
corresponding to the dialect, clause element, the column
names within the VALUES or SET clause of an INSERT or UPDATE,
as well as the "batch" mode for an INSERT or UPDATE statement.
The format of this dictionary is not guaranteed to stay the
same in future releases.
This option is usually more appropriate
to use via the
:meth:`sqlalchemy.engine.base.Connection.execution_options()`
method of :class:`Connection`, rather than upon individual
statement objects, though the effect is the same.
See also:
:meth:`sqlalchemy.engine.base.Connection.execution_options()`
:meth:`sqlalchemy.orm.query.Query.execution_options()`
"""
self._execution_options = self._execution_options.union(kw)
def execute(self, *multiparams, **params):
"""Compile and execute this :class:`.Executable`."""
e = self.bind
if e is None:
label = getattr(self, 'description', self.__class__.__name__)
msg = ('This %s is not bound and does not support direct '
'execution. Supply this statement to a Connection or '
'Engine for execution. Or, assign a bind to the statement '
'or the Metadata of its underlying tables to enable '
'implicit execution via this method.' % label)
raise exc.UnboundExecutionError(msg)
return e._execute_clauseelement(self, multiparams, params)
def scalar(self, *multiparams, **params):
"""Compile and execute this :class:`.Executable`, returning the
result's scalar representation.
"""
return self.execute(*multiparams, **params).scalar()
# legacy, some outside users may be calling this
_Executable = Executable
class _TextClause(Executable, ClauseElement):
"""Represent a literal SQL text fragment.
Public constructor is the :func:`text()` function.
"""
__visit_name__ = 'textclause'
_bind_params_regex = re.compile(r'(?<![:\w\x5c]):(\w+)(?!:)', re.UNICODE)
_execution_options = \
Executable._execution_options.union({'autocommit'
: PARSE_AUTOCOMMIT})
@property
def _select_iterable(self):
return (self,)
_hide_froms = []
def __init__(
self,
text='',
bind=None,
bindparams=None,
typemap=None,
autocommit=None,
):
self._bind = bind
self.bindparams = {}
self.typemap = typemap
if autocommit is not None:
util.warn_deprecated('autocommit on text() is deprecated. '
'Use .execution_options(autocommit=Tru'
'e)')
self._execution_options = \
self._execution_options.union({'autocommit'
: autocommit})
if typemap is not None:
for key in typemap.keys():
typemap[key] = sqltypes.to_instance(typemap[key])
def repl(m):
self.bindparams[m.group(1)] = bindparam(m.group(1))
return ':%s' % m.group(1)
# scan the string and search for bind parameter names, add them
# to the list of bindparams
self.text = self._bind_params_regex.sub(repl, text)
if bindparams is not None:
for b in bindparams:
self.bindparams[b.key] = b
@property
def type(self):
if self.typemap is not None and len(self.typemap) == 1:
return list(self.typemap)[0]
else:
return sqltypes.NULLTYPE
def self_group(self, against=None):
if against is operators.in_op:
return _Grouping(self)
else:
return self
def _copy_internals(self, clone=_clone):
self.bindparams = dict((b.key, clone(b))
for b in self.bindparams.values())
def get_children(self, **kwargs):
return self.bindparams.values()
class _Null(ColumnElement):
"""Represent the NULL keyword in a SQL statement.
Public constructor is the :func:`null()` function.
"""
__visit_name__ = 'null'
def __init__(self):
self.type = sqltypes.NULLTYPE
class ClauseList(ClauseElement):
"""Describe a list of clauses, separated by an operator.
By default, is comma-separated, such as a column listing.
"""
__visit_name__ = 'clauselist'
def __init__(self, *clauses, **kwargs):
self.operator = kwargs.pop('operator', operators.comma_op)
self.group = kwargs.pop('group', True)
self.group_contents = kwargs.pop('group_contents', True)
if self.group_contents:
self.clauses = [
_literal_as_text(clause).self_group(against=self.operator)
for clause in clauses if clause is not None]
else:
self.clauses = [
_literal_as_text(clause)
for clause in clauses if clause is not None]
@util.memoized_property
def type(self):
if self.clauses:
return self.clauses[0].type
else:
return sqltypes.NULLTYPE
def __iter__(self):
return iter(self.clauses)
def __len__(self):
return len(self.clauses)
@property
def _select_iterable(self):
return iter(self)
def append(self, clause):
# TODO: not sure if i like the 'group_contents' flag. need to
# define the difference between a ClauseList of ClauseLists,
# and a "flattened" ClauseList of ClauseLists. flatten()
# method ?
if self.group_contents:
self.clauses.append(_literal_as_text(clause).\
self_group(against=self.operator))
else:
self.clauses.append(_literal_as_text(clause))
def _copy_internals(self, clone=_clone):
self.clauses = [clone(clause) for clause in self.clauses]
def get_children(self, **kwargs):
return self.clauses
@property
def _from_objects(self):
return list(itertools.chain(*[c._from_objects for c in self.clauses]))
def self_group(self, against=None):
if self.group and operators.is_precedent(self.operator, against):
return _Grouping(self)
else:
return self
def compare(self, other, **kw):
"""Compare this :class:`ClauseList` to the given :class:`ClauseList`,
including a comparison of all the clause items.
"""
if not isinstance(other, ClauseList) and len(self.clauses) == 1:
return self.clauses[0].compare(other, **kw)
elif isinstance(other, ClauseList) and \
len(self.clauses) == len(other.clauses):
for i in range(0, len(self.clauses)):
if not self.clauses[i].compare(other.clauses[i], **kw):
return False
else:
return self.operator == other.operator
else:
return False
class BooleanClauseList(ClauseList, ColumnElement):
__visit_name__ = 'clauselist'
def __init__(self, *clauses, **kwargs):
super(BooleanClauseList, self).__init__(*clauses, **kwargs)
self.type = sqltypes.to_instance(kwargs.get('type_',
sqltypes.Boolean))
@property
def _select_iterable(self):
return (self, )
class _Tuple(ClauseList, ColumnElement):
def __init__(self, *clauses, **kw):
clauses = [_literal_as_binds(c) for c in clauses]
super(_Tuple, self).__init__(*clauses, **kw)
self.type = _type_from_args(clauses)
@property
def _select_iterable(self):
return (self, )
def _bind_param(self, operator, obj):
return _Tuple(*[
_BindParamClause(None, o, _compared_to_operator=operator,
_compared_to_type=self.type, unique=True)
for o in obj
]).self_group()
class _Case(ColumnElement):
__visit_name__ = 'case'
def __init__(self, whens, value=None, else_=None):
try:
whens = util.dictlike_iteritems(whens)
except TypeError:
pass
if value is not None:
whenlist = [
(_literal_as_binds(c).self_group(),
_literal_as_binds(r)) for (c, r) in whens
]
else:
whenlist = [
(_no_literals(c).self_group(),
_literal_as_binds(r)) for (c, r) in whens
]
if whenlist:
type_ = list(whenlist[-1])[-1].type
else:
type_ = None
if value is None:
self.value = None
else:
self.value = _literal_as_binds(value)
self.type = type_
self.whens = whenlist
if else_ is not None:
self.else_ = _literal_as_binds(else_)
else:
self.else_ = None
def _copy_internals(self, clone=_clone):
if self.value is not None:
self.value = clone(self.value)
self.whens = [(clone(x), clone(y)) for x, y in self.whens]
if self.else_ is not None:
self.else_ = clone(self.else_)
def get_children(self, **kwargs):
if self.value is not None:
yield self.value
for x, y in self.whens:
yield x
yield y
if self.else_ is not None:
yield self.else_
@property
def _from_objects(self):
return list(itertools.chain(*[x._from_objects for x in
self.get_children()]))
class FunctionElement(Executable, ColumnElement, FromClause):
"""Base for SQL function-oriented constructs."""
def __init__(self, *clauses, **kwargs):
args = [_literal_as_binds(c, self.name) for c in clauses]
self.clause_expr = ClauseList(
operator=operators.comma_op,
group_contents=True, *args).\
self_group()
@property
def columns(self):
return [self]
@util.memoized_property
def clauses(self):
return self.clause_expr.element
@property
def _from_objects(self):
return self.clauses._from_objects
def get_children(self, **kwargs):
return self.clause_expr,
def _copy_internals(self, clone=_clone):
self.clause_expr = clone(self.clause_expr)
self._reset_exported()
util.reset_memoized(self, 'clauses')
def select(self):
s = select([self])
if self._execution_options:
s = s.execution_options(**self._execution_options)
return s
def scalar(self):
return self.select().execute().scalar()
def execute(self):
return self.select().execute()
def _bind_param(self, operator, obj):
return _BindParamClause(None, obj, _compared_to_operator=operator,
_compared_to_type=self.type, unique=True)
class Function(FunctionElement):
"""Describe a named SQL function."""
__visit_name__ = 'function'
def __init__(self, name, *clauses, **kw):
self.packagenames = kw.pop('packagenames', None) or []
self.name = name
self._bind = kw.get('bind', None)
self.type = sqltypes.to_instance(kw.get('type_', None))
FunctionElement.__init__(self, *clauses, **kw)
def _bind_param(self, operator, obj):
return _BindParamClause(self.name, obj,
_compared_to_operator=operator,
_compared_to_type=self.type,
unique=True)
class _Cast(ColumnElement):
__visit_name__ = 'cast'
def __init__(self, clause, totype, **kwargs):
self.type = sqltypes.to_instance(totype)
self.clause = _literal_as_binds(clause, None)
self.typeclause = _TypeClause(self.type)
def _copy_internals(self, clone=_clone):
self.clause = clone(self.clause)
self.typeclause = clone(self.typeclause)
def get_children(self, **kwargs):
return self.clause, self.typeclause
@property
def _from_objects(self):
return self.clause._from_objects
class _Extract(ColumnElement):
__visit_name__ = 'extract'
def __init__(self, field, expr, **kwargs):
self.type = sqltypes.Integer()
self.field = field
self.expr = _literal_as_binds(expr, None)
def _copy_internals(self, clone=_clone):
self.expr = clone(self.expr)
def get_children(self, **kwargs):
return self.expr,
@property
def _from_objects(self):
return self.expr._from_objects
class _UnaryExpression(ColumnElement):
__visit_name__ = 'unary'
def __init__(self, element, operator=None, modifier=None,
type_=None, negate=None):
self.operator = operator
self.modifier = modifier
self.element = _literal_as_text(element).\
self_group(against=self.operator or self.modifier)
self.type = sqltypes.to_instance(type_)
self.negate = negate
@property
def _from_objects(self):
return self.element._from_objects
def _copy_internals(self, clone=_clone):
self.element = clone(self.element)
def get_children(self, **kwargs):
return self.element,
def compare(self, other, **kw):
"""Compare this :class:`_UnaryExpression` against the given
:class:`ClauseElement`."""
return (
isinstance(other, _UnaryExpression) and
self.operator == other.operator and
self.modifier == other.modifier and
self.element.compare(other.element, **kw)
)
def _negate(self):
if self.negate is not None:
return _UnaryExpression(
self.element,
operator=self.negate,
negate=self.operator,
modifier=self.modifier,
type_=self.type)
else:
return super(_UnaryExpression, self)._negate()
def self_group(self, against=None):
if self.operator and operators.is_precedent(self.operator,
against):
return _Grouping(self)
else:
return self
class _BinaryExpression(ColumnElement):
"""Represent an expression that is ``LEFT <operator> RIGHT``."""
__visit_name__ = 'binary'
def __init__(self, left, right, operator, type_=None,
negate=None, modifiers=None):
self.left = _literal_as_text(left).self_group(against=operator)
self.right = _literal_as_text(right).self_group(against=operator)
self.operator = operator
self.type = sqltypes.to_instance(type_)
self.negate = negate
if modifiers is None:
self.modifiers = {}
else:
self.modifiers = modifiers
def __nonzero__(self):
try:
return self.operator(hash(self.left), hash(self.right))
except:
raise TypeError("Boolean value of this clause is not defined")
@property
def _from_objects(self):
return self.left._from_objects + self.right._from_objects
def _copy_internals(self, clone=_clone):
self.left = clone(self.left)
self.right = clone(self.right)
def get_children(self, **kwargs):
return self.left, self.right
def compare(self, other, **kw):
"""Compare this :class:`_BinaryExpression` against the
given :class:`_BinaryExpression`."""
return (
isinstance(other, _BinaryExpression) and
self.operator == other.operator and
(
self.left.compare(other.left, **kw) and
self.right.compare(other.right, **kw) or
(
operators.is_commutative(self.operator) and
self.left.compare(other.right, **kw) and
self.right.compare(other.left, **kw)
)
)
)
def self_group(self, against=None):
if operators.is_precedent(self.operator, against):
return _Grouping(self)
else:
return self
def _negate(self):
if self.negate is not None:
return _BinaryExpression(
self.left,
self.right,
self.negate,
negate=self.operator,
type_=sqltypes.BOOLEANTYPE,
modifiers=self.modifiers)
else:
return super(_BinaryExpression, self)._negate()
class _Exists(_UnaryExpression):
__visit_name__ = _UnaryExpression.__visit_name__
_from_objects = []
def __init__(self, *args, **kwargs):
if args and isinstance(args[0], (_SelectBaseMixin, _ScalarSelect)):
s = args[0]
else:
if not args:
args = ([literal_column('*')],)
s = select(*args, **kwargs).as_scalar().self_group()
_UnaryExpression.__init__(self, s, operator=operators.exists,
type_=sqltypes.Boolean)
def select(self, whereclause=None, **params):
return select([self], whereclause, **params)
def correlate(self, fromclause):
e = self._clone()
e.element = self.element.correlate(fromclause).self_group()
return e
def select_from(self, clause):
"""return a new exists() construct with the given expression set as
its FROM clause.
"""
e = self._clone()
e.element = self.element.select_from(clause).self_group()
return e
def where(self, clause):
"""return a new exists() construct with the given expression added to
its WHERE clause, joined to the existing clause via AND, if any.
"""
e = self._clone()
e.element = self.element.where(clause).self_group()
return e
class Join(FromClause):
"""represent a ``JOIN`` construct between two :class:`FromClause`
elements.
The public constructor function for :class:`Join` is the module-level
:func:`join()` function, as well as the :func:`join()` method available
off all :class:`FromClause` subclasses.
"""
__visit_name__ = 'join'
def __init__(self, left, right, onclause=None, isouter=False):
self.left = _literal_as_text(left)
self.right = _literal_as_text(right).self_group()
if onclause is None:
self.onclause = self._match_primaries(self.left, self.right)
else:
self.onclause = onclause
self.isouter = isouter
self.__folded_equivalents = None
@property
def description(self):
return "Join object on %s(%d) and %s(%d)" % (
self.left.description,
id(self.left),
self.right.description,
id(self.right))
def is_derived_from(self, fromclause):
return fromclause is self or \
self.left.is_derived_from(fromclause) or\
self.right.is_derived_from(fromclause)
def self_group(self, against=None):
return _FromGrouping(self)
def _populate_column_collection(self):
columns = [c for c in self.left.columns] + \
[c for c in self.right.columns]
self._primary_key.extend(sqlutil.reduce_columns(
(c for c in columns if c.primary_key), self.onclause))
self._columns.update((col._label, col) for col in columns)
self._foreign_keys.update(itertools.chain(
*[col.foreign_keys for col in columns]))
def _copy_internals(self, clone=_clone):
self._reset_exported()
self.left = clone(self.left)
self.right = clone(self.right)
self.onclause = clone(self.onclause)
self.__folded_equivalents = None
def get_children(self, **kwargs):
return self.left, self.right, self.onclause
def _match_primaries(self, left, right):
if isinstance(left, Join):
left_right = left.right
else:
left_right = None
return sqlutil.join_condition(left, right, a_subset=left_right)
def select(self, whereclause=None, fold_equivalents=False, **kwargs):
"""Create a :class:`Select` from this :class:`Join`.
:param whereclause: the WHERE criterion that will be sent to
the :func:`select()` function
:param fold_equivalents: based on the join criterion of this
:class:`Join`, do not include
repeat column names in the column list of the resulting
select, for columns that are calculated to be "equivalent"
based on the join criterion of this :class:`Join`. This will
recursively apply to any joins directly nested by this one
as well.
:param \**kwargs: all other kwargs are sent to the
underlying :func:`select()` function.
"""
if fold_equivalents:
collist = sqlutil.folded_equivalents(self)
else:
collist = [self.left, self.right]
return select(collist, whereclause, from_obj=[self], **kwargs)
@property
def bind(self):
return self.left.bind or self.right.bind
def alias(self, name=None):
"""Create a :class:`Select` out of this :class:`Join` clause and
return an :class:`Alias` of it.
The :class:`Select` is not correlating.
"""
return self.select(use_labels=True, correlate=False).alias(name)
@property
def _hide_froms(self):
return itertools.chain(*[_from_objects(x.left, x.right)
for x in self._cloned_set])
@property
def _from_objects(self):
return [self] + \
self.onclause._from_objects + \
self.left._from_objects + \
self.right._from_objects
class Alias(FromClause):
"""Represents an table or selectable alias (AS).
Represents an alias, as typically applied to any table or
sub-select within a SQL statement using the ``AS`` keyword (or
without the keyword on certain databases such as Oracle).
This object is constructed from the :func:`alias()` module level
function as well as the :func:`alias()` method available on all
:class:`FromClause` subclasses.
"""
__visit_name__ = 'alias'
named_with_column = True
def __init__(self, selectable, alias=None):
baseselectable = selectable
while isinstance(baseselectable, Alias):
baseselectable = baseselectable.element
self.original = baseselectable
self.supports_execution = baseselectable.supports_execution
if self.supports_execution:
self._execution_options = baseselectable._execution_options
self.element = selectable
if alias is None:
if self.original.named_with_column:
alias = getattr(self.original, 'name', None)
alias = _generated_label('%%(%d %s)s' % (id(self), alias
or 'anon'))
self.name = alias
@property
def description(self):
# Py3K
#return self.name
# Py2K
return self.name.encode('ascii', 'backslashreplace')
# end Py2K
def as_scalar(self):
try:
return self.element.as_scalar()
except AttributeError:
raise AttributeError("Element %s does not support "
"'as_scalar()'" % self.element)
def is_derived_from(self, fromclause):
if fromclause in self._cloned_set:
return True
return self.element.is_derived_from(fromclause)
def _populate_column_collection(self):
for col in self.element.columns:
col._make_proxy(self)
def _copy_internals(self, clone=_clone):
self._reset_exported()
self.element = _clone(self.element)
baseselectable = self.element
while isinstance(baseselectable, Alias):
baseselectable = baseselectable.element
self.original = baseselectable
def get_children(self, column_collections=True,
aliased_selectables=True, **kwargs):
if column_collections:
for c in self.c:
yield c
if aliased_selectables:
yield self.element
@property
def _from_objects(self):
return [self]
@property
def bind(self):
return self.element.bind
class _Grouping(ColumnElement):
"""Represent a grouping within a column expression"""
__visit_name__ = 'grouping'
def __init__(self, element):
self.element = element
self.type = getattr(element, 'type', None)
@property
def _label(self):
return getattr(self.element, '_label', None) or self.anon_label
def _copy_internals(self, clone=_clone):
self.element = clone(self.element)
def get_children(self, **kwargs):
return self.element,
@property
def _from_objects(self):
return self.element._from_objects
def __getattr__(self, attr):
return getattr(self.element, attr)
def __getstate__(self):
return {'element':self.element, 'type':self.type}
def __setstate__(self, state):
self.element = state['element']
self.type = state['type']
class _FromGrouping(FromClause):
"""Represent a grouping of a FROM clause"""
__visit_name__ = 'grouping'
def __init__(self, element):
self.element = element
@property
def columns(self):
return self.element.columns
@property
def _hide_froms(self):
return self.element._hide_froms
def get_children(self, **kwargs):
return self.element,
def _copy_internals(self, clone=_clone):
self.element = clone(self.element)
@property
def _from_objects(self):
return self.element._from_objects
def __getattr__(self, attr):
return getattr(self.element, attr)
def __getstate__(self):
return {'element':self.element}
def __setstate__(self, state):
self.element = state['element']
class _Label(ColumnElement):
"""Represents a column label (AS).
Represent a label, as typically applied to any column-level
element using the ``AS`` sql keyword.
This object is constructed from the :func:`label()` module level
function as well as the :func:`label()` method available on all
:class:`ColumnElement` subclasses.
"""
__visit_name__ = 'label'
def __init__(self, name, element, type_=None):
while isinstance(element, _Label):
element = element.element
self.name = self.key = self._label = name \
or _generated_label('%%(%d %s)s' % (id(self),
getattr(element, 'name', 'anon')))
self._element = element
self._type = type_
self.quote = element.quote
self.proxies = [element]
@util.memoized_property
def type(self):
return sqltypes.to_instance(
self._type or getattr(self._element, 'type', None)
)
@util.memoized_property
def element(self):
return self._element.self_group(against=operators.as_)
def self_group(self, against=None):
sub_element = self._element.self_group(against=against)
if sub_element is not self._element:
return _Label(self.name,
sub_element,
type_=self._type)
else:
return self._element
@property
def primary_key(self):
return self.element.primary_key
@property
def foreign_keys(self):
return self.element.foreign_keys
def get_children(self, **kwargs):
return self.element,
def _copy_internals(self, clone=_clone):
self.element = clone(self.element)
@property
def _from_objects(self):
return self.element._from_objects
def _make_proxy(self, selectable, name = None):
if isinstance(self.element, (Selectable, ColumnElement)):
e = self.element._make_proxy(selectable, name=self.name)
else:
e = column(self.name)._make_proxy(selectable=selectable)
e.proxies.append(self)
return e
class ColumnClause(_Immutable, ColumnElement):
"""Represents a generic column expression from any textual string.
This includes columns associated with tables, aliases and select
statements, but also any arbitrary text. May or may not be bound
to an underlying :class:`Selectable`. :class:`ColumnClause` is usually
created publically via the :func:`column()` function or the
:func:`literal_column()` function.
text
the text of the element.
selectable
parent selectable.
type
``TypeEngine`` object which can associate this :class:`ColumnClause`
with a type.
is_literal
if True, the :class:`ColumnClause` is assumed to be an exact
expression that will be delivered to the output with no quoting
rules applied regardless of case sensitive settings. the
:func:`literal_column()` function is usually used to create such a
:class:`ColumnClause`.
"""
__visit_name__ = 'column'
onupdate = default = server_default = server_onupdate = None
def __init__(self, text, selectable=None, type_=None, is_literal=False):
self.key = self.name = text
self.table = selectable
self.type = sqltypes.to_instance(type_)
self.is_literal = is_literal
@util.memoized_property
def description(self):
# Py3K
#return self.name
# Py2K
return self.name.encode('ascii', 'backslashreplace')
# end Py2K
@util.memoized_property
def _label(self):
if self.is_literal:
return None
elif self.table is not None and self.table.named_with_column:
if getattr(self.table, 'schema', None):
label = self.table.schema.replace('.', '_') + "_" + \
_escape_for_generated(self.table.name) + "_" + \
_escape_for_generated(self.name)
else:
label = _escape_for_generated(self.table.name) + "_" + \
_escape_for_generated(self.name)
# ensure the label name doesn't conflict with that
# of an existing column
if label in self.table.c:
_label = label
counter = 1
while _label in self.table.c:
_label = label + "_" + str(counter)
counter += 1
label = _label
return _generated_label(label)
else:
return self.name
def label(self, name):
if name is None:
return self
else:
return super(ColumnClause, self).label(name)
@property
def _from_objects(self):
if self.table is not None:
return [self.table]
else:
return []
def _bind_param(self, operator, obj):
return _BindParamClause(self.name, obj,
_compared_to_operator=operator,
_compared_to_type=self.type,
unique=True)
def _make_proxy(self, selectable, name=None, attach=True):
# propagate the "is_literal" flag only if we are keeping our name,
# otherwise its considered to be a label
is_literal = self.is_literal and (name is None or name == self.name)
c = self._constructor(
name or self.name,
selectable=selectable,
type_=self.type,
is_literal=is_literal
)
c.proxies = [self]
if attach:
selectable.columns[c.name] = c
return c
class TableClause(_Immutable, FromClause):
"""Represents a "table" construct.
Note that this represents tables only as another syntactical
construct within SQL expressions; it does not provide schema-level
functionality.
"""
__visit_name__ = 'table'
named_with_column = True
def __init__(self, name, *columns):
super(TableClause, self).__init__()
self.name = self.fullname = name
self._columns = ColumnCollection()
self._primary_key = ColumnSet()
self._foreign_keys = set()
for c in columns:
self.append_column(c)
def _export_columns(self):
raise NotImplementedError()
@util.memoized_property
def description(self):
# Py3K
#return self.name
# Py2K
return self.name.encode('ascii', 'backslashreplace')
# end Py2K
def append_column(self, c):
self._columns[c.name] = c
c.table = self
def get_children(self, column_collections=True, **kwargs):
if column_collections:
return [c for c in self.c]
else:
return []
def count(self, whereclause=None, **params):
"""return a SELECT COUNT generated against this
:class:`TableClause`."""
if self.primary_key:
col = list(self.primary_key)[0]
else:
col = list(self.columns)[0]
return select(
[func.count(col).label('tbl_row_count')],
whereclause,
from_obj=[self],
**params)
def insert(self, values=None, inline=False, **kwargs):
"""Generate an :func:`insert()` construct."""
return insert(self, values=values, inline=inline, **kwargs)
def update(self, whereclause=None, values=None, inline=False, **kwargs):
"""Generate an :func:`update()` construct."""
return update(self, whereclause=whereclause,
values=values, inline=inline, **kwargs)
def delete(self, whereclause=None, **kwargs):
"""Generate a :func:`delete()` construct."""
return delete(self, whereclause, **kwargs)
@property
def _from_objects(self):
return [self]
class _SelectBaseMixin(Executable):
"""Base class for :class:`Select` and ``CompoundSelects``."""
def __init__(self,
use_labels=False,
for_update=False,
limit=None,
offset=None,
order_by=None,
group_by=None,
bind=None,
autocommit=None):
self.use_labels = use_labels
self.for_update = for_update
if autocommit is not None:
util.warn_deprecated('autocommit on select() is '
'deprecated. Use .execution_options(a'
'utocommit=True)')
self._execution_options = \
self._execution_options.union({'autocommit'
: autocommit})
self._limit = limit
self._offset = offset
self._bind = bind
self._order_by_clause = ClauseList(*util.to_list(order_by) or [])
self._group_by_clause = ClauseList(*util.to_list(group_by) or [])
def as_scalar(self):
"""return a 'scalar' representation of this selectable, which can be
used as a column expression.
Typically, a select statement which has only one column in its columns
clause is eligible to be used as a scalar expression.
The returned object is an instance of
:class:`_ScalarSelect`.
"""
return _ScalarSelect(self)
@_generative
def apply_labels(self):
"""return a new selectable with the 'use_labels' flag set to True.
This will result in column expressions being generated using labels
against their table name, such as "SELECT somecolumn AS
tablename_somecolumn". This allows selectables which contain multiple
FROM clauses to produce a unique set of column names regardless of
name conflicts among the individual FROM clauses.
"""
self.use_labels = True
def label(self, name):
"""return a 'scalar' representation of this selectable, embedded as a
subquery with a label.
See also ``as_scalar()``.
"""
return self.as_scalar().label(name)
@_generative
@util.deprecated('0.6',
message=":func:`.autocommit` is deprecated. Use "
":func:`.Executable.execution_options` with the "
"'autocommit' flag.")
def autocommit(self):
"""return a new selectable with the 'autocommit' flag set to
True."""
self._execution_options = \
self._execution_options.union({'autocommit': True})
def _generate(self):
"""Override the default _generate() method to also clear out
exported collections."""
s = self.__class__.__new__(self.__class__)
s.__dict__ = self.__dict__.copy()
s._reset_exported()
return s
@_generative
def limit(self, limit):
"""return a new selectable with the given LIMIT criterion
applied."""
self._limit = limit
@_generative
def offset(self, offset):
"""return a new selectable with the given OFFSET criterion
applied."""
self._offset = offset
@_generative
def order_by(self, *clauses):
"""return a new selectable with the given list of ORDER BY
criterion applied.
The criterion will be appended to any pre-existing ORDER BY
criterion.
"""
self.append_order_by(*clauses)
@_generative
def group_by(self, *clauses):
"""return a new selectable with the given list of GROUP BY
criterion applied.
The criterion will be appended to any pre-existing GROUP BY
criterion.
"""
self.append_group_by(*clauses)
def append_order_by(self, *clauses):
"""Append the given ORDER BY criterion applied to this selectable.
The criterion will be appended to any pre-existing ORDER BY criterion.
"""
if len(clauses) == 1 and clauses[0] is None:
self._order_by_clause = ClauseList()
else:
if getattr(self, '_order_by_clause', None) is not None:
clauses = list(self._order_by_clause) + list(clauses)
self._order_by_clause = ClauseList(*clauses)
def append_group_by(self, *clauses):
"""Append the given GROUP BY criterion applied to this selectable.
The criterion will be appended to any pre-existing GROUP BY criterion.
"""
if len(clauses) == 1 and clauses[0] is None:
self._group_by_clause = ClauseList()
else:
if getattr(self, '_group_by_clause', None) is not None:
clauses = list(self._group_by_clause) + list(clauses)
self._group_by_clause = ClauseList(*clauses)
@property
def _from_objects(self):
return [self]
class _ScalarSelect(_Grouping):
_from_objects = []
def __init__(self, element):
self.element = element
self.type = element._scalar_type()
@property
def columns(self):
raise exc.InvalidRequestError('Scalar Select expression has no '
'columns; use this object directly within a '
'column-level expression.')
c = columns
def self_group(self, **kwargs):
return self
def _make_proxy(self, selectable, name):
return list(self.inner_columns)[0]._make_proxy(selectable, name)
class CompoundSelect(_SelectBaseMixin, FromClause):
"""Forms the basis of ``UNION``, ``UNION ALL``, and other
SELECT-based set operations."""
__visit_name__ = 'compound_select'
UNION = util.symbol('UNION')
UNION_ALL = util.symbol('UNION ALL')
EXCEPT = util.symbol('EXCEPT')
EXCEPT_ALL = util.symbol('EXCEPT ALL')
INTERSECT = util.symbol('INTERSECT')
INTERSECT_ALL = util.symbol('INTERSECT ALL')
def __init__(self, keyword, *selects, **kwargs):
self._should_correlate = kwargs.pop('correlate', False)
self.keyword = keyword
self.selects = []
numcols = None
# some DBs do not like ORDER BY in the inner queries of a UNION, etc.
for n, s in enumerate(selects):
s = _clause_element_as_expr(s)
if not numcols:
numcols = len(s.c)
elif len(s.c) != numcols:
raise exc.ArgumentError('All selectables passed to '
'CompoundSelect must have identical numbers of '
'columns; select #%d has %d columns, select '
'#%d has %d' % (1, len(self.selects[0].c), n
+ 1, len(s.c)))
self.selects.append(s.self_group(self))
_SelectBaseMixin.__init__(self, **kwargs)
def _scalar_type(self):
return self.selects[0]._scalar_type()
def self_group(self, against=None):
return _FromGrouping(self)
def is_derived_from(self, fromclause):
for s in self.selects:
if s.is_derived_from(fromclause):
return True
return False
def _populate_column_collection(self):
for cols in zip(*[s.c for s in self.selects]):
# this is a slightly hacky thing - the union exports a
# column that resembles just that of the *first* selectable.
# to get at a "composite" column, particularly foreign keys,
# you have to dig through the proxies collection which we
# generate below. We may want to improve upon this, such as
# perhaps _make_proxy can accept a list of other columns
# that are "shared" - schema.column can then copy all the
# ForeignKeys in. this would allow the union() to have all
# those fks too.
proxy = cols[0]._make_proxy(self, name=self.use_labels
and cols[0]._label or None)
# hand-construct the "proxies" collection to include all
# derived columns place a 'weight' annotation corresponding
# to how low in the list of select()s the column occurs, so
# that the corresponding_column() operation can resolve
# conflicts
proxy.proxies = [c._annotate({'weight': i + 1}) for (i,
c) in enumerate(cols)]
def _copy_internals(self, clone=_clone):
self._reset_exported()
self.selects = [clone(s) for s in self.selects]
if hasattr(self, '_col_map'):
del self._col_map
for attr in ('_order_by_clause', '_group_by_clause'):
if getattr(self, attr) is not None:
setattr(self, attr, clone(getattr(self, attr)))
def get_children(self, column_collections=True, **kwargs):
return (column_collections and list(self.c) or []) \
+ [self._order_by_clause, self._group_by_clause] \
+ list(self.selects)
def bind(self):
if self._bind:
return self._bind
for s in self.selects:
e = s.bind
if e:
return e
else:
return None
def _set_bind(self, bind):
self._bind = bind
bind = property(bind, _set_bind)
class Select(_SelectBaseMixin, FromClause):
"""Represents a ``SELECT`` statement.
Select statements support appendable clauses, as well as the
ability to execute themselves and return a result set.
"""
__visit_name__ = 'select'
_prefixes = ()
_hints = util.frozendict()
def __init__(self,
columns,
whereclause=None,
from_obj=None,
distinct=False,
having=None,
correlate=True,
prefixes=None,
**kwargs):
"""Construct a Select object.
The public constructor for Select is the
:func:`select` function; see that function for
argument descriptions.
Additional generative and mutator methods are available on the
:class:`_SelectBaseMixin` superclass.
"""
self._should_correlate = correlate
self._distinct = distinct
self._correlate = set()
self._froms = util.OrderedSet()
try:
cols_present = bool(columns)
except TypeError:
raise exc.ArgumentError("columns argument to select() must "
"be a Python list or other iterable")
if cols_present:
self._raw_columns = []
for c in columns:
c = _literal_as_column(c)
if isinstance(c, _ScalarSelect):
c = c.self_group(against=operators.comma_op)
self._raw_columns.append(c)
self._froms.update(_from_objects(*self._raw_columns))
else:
self._raw_columns = []
if whereclause is not None:
self._whereclause = _literal_as_text(whereclause)
self._froms.update(_from_objects(self._whereclause))
else:
self._whereclause = None
if from_obj is not None:
for f in util.to_list(from_obj):
if _is_literal(f):
self._froms.add(_TextClause(f))
else:
self._froms.add(f)
if having is not None:
self._having = _literal_as_text(having)
else:
self._having = None
if prefixes:
self._prefixes = tuple([_literal_as_text(p) for p in prefixes])
_SelectBaseMixin.__init__(self, **kwargs)
def _get_display_froms(self, existing_froms=None):
"""Return the full list of 'from' clauses to be displayed.
Takes into account a set of existing froms which may be
rendered in the FROM clause of enclosing selects; this Select
may want to leave those absent if it is automatically
correlating.
"""
froms = self._froms
toremove = itertools.chain(*[f._hide_froms for f in froms])
if toremove:
froms = froms.difference(toremove)
if len(froms) > 1 or self._correlate:
if self._correlate:
froms = froms.difference(_cloned_intersection(froms,
self._correlate))
if self._should_correlate and existing_froms:
froms = froms.difference(_cloned_intersection(froms,
existing_froms))
if not len(froms):
raise exc.InvalidRequestError("Select statement '%s"
"' returned no FROM clauses due to "
"auto-correlation; specify "
"correlate(<tables>) to control "
"correlation manually." % self)
return froms
def _scalar_type(self):
elem = self._raw_columns[0]
cols = list(elem._select_iterable)
return cols[0].type
@property
def froms(self):
"""Return the displayed list of FromClause elements."""
return self._get_display_froms()
@_generative
def with_hint(self, selectable, text, dialect_name='*'):
"""Add an indexing hint for the given selectable to this
:class:`Select`.
The text of the hint is rendered in the appropriate
location for the database backend in use, relative
to the given :class:`.Table` or :class:`.Alias` passed as the
*selectable* argument. The dialect implementation
typically uses Python string substitution syntax
with the token ``%(name)s`` to render the name of
the table or alias. E.g. when using Oracle, the
following::
select([mytable]).\\
with_hint(mytable, "+ index(%(name)s ix_mytable)")
Would render SQL as::
select /*+ index(mytable ix_mytable) */ ... from mytable
The ``dialect_name`` option will limit the rendering of a particular
hint to a particular backend. Such as, to add hints for both Oracle
and Sybase simultaneously::
select([mytable]).\\
with_hint(mytable, "+ index(%(name)s ix_mytable)", 'oracle').\\
with_hint(mytable, "WITH INDEX ix_mytable", 'sybase')
"""
self._hints = self._hints.union({(selectable, dialect_name):text})
@property
def type(self):
raise exc.InvalidRequestError("Select objects don't have a type. "
"Call as_scalar() on this Select object "
"to return a 'scalar' version of this Select.")
@util.memoized_instancemethod
def locate_all_froms(self):
"""return a Set of all FromClause elements referenced by this Select.
This set is a superset of that returned by the ``froms`` property,
which is specifically for those FromClause elements that would
actually be rendered.
"""
return self._froms.union(_from_objects(*list(self._froms)))
@property
def inner_columns(self):
"""an iterator of all ColumnElement expressions which would
be rendered into the columns clause of the resulting SELECT statement.
"""
return _select_iterables(self._raw_columns)
def is_derived_from(self, fromclause):
if self in fromclause._cloned_set:
return True
for f in self.locate_all_froms():
if f.is_derived_from(fromclause):
return True
return False
def _copy_internals(self, clone=_clone):
self._reset_exported()
from_cloned = dict((f, clone(f))
for f in self._froms.union(self._correlate))
self._froms = util.OrderedSet(from_cloned[f] for f in self._froms)
self._correlate = set(from_cloned[f] for f in self._correlate)
self._raw_columns = [clone(c) for c in self._raw_columns]
for attr in '_whereclause', '_having', '_order_by_clause', \
'_group_by_clause':
if getattr(self, attr) is not None:
setattr(self, attr, clone(getattr(self, attr)))
def get_children(self, column_collections=True, **kwargs):
"""return child elements as per the ClauseElement specification."""
return (column_collections and list(self.columns) or []) + \
self._raw_columns + list(self._froms) + \
[x for x in
(self._whereclause, self._having,
self._order_by_clause, self._group_by_clause)
if x is not None]
@_generative
def column(self, column):
"""return a new select() construct with the given column expression
added to its columns clause.
"""
column = _literal_as_column(column)
if isinstance(column, _ScalarSelect):
column = column.self_group(against=operators.comma_op)
self._raw_columns = self._raw_columns + [column]
self._froms = self._froms.union(_from_objects(column))
@_generative
def with_only_columns(self, columns):
"""return a new select() construct with its columns clause replaced
with the given columns.
"""
self._raw_columns = [
isinstance(c, _ScalarSelect) and
c.self_group(against=operators.comma_op) or c
for c in [_literal_as_column(c) for c in columns]
]
@_generative
def where(self, whereclause):
"""return a new select() construct with the given expression added to
its WHERE clause, joined to the existing clause via AND, if any.
"""
self.append_whereclause(whereclause)
@_generative
def having(self, having):
"""return a new select() construct with the given expression added to
its HAVING clause, joined to the existing clause via AND, if any.
"""
self.append_having(having)
@_generative
def distinct(self):
"""return a new select() construct which will apply DISTINCT to its
columns clause.
"""
self._distinct = True
@_generative
def prefix_with(self, clause):
"""return a new select() construct which will apply the given
expression to the start of its columns clause, not using any commas.
"""
clause = _literal_as_text(clause)
self._prefixes = self._prefixes + (clause,)
@_generative
def select_from(self, fromclause):
"""return a new select() construct with the given FROM expression
applied to its list of FROM objects.
"""
fromclause = _literal_as_text(fromclause)
self._froms = self._froms.union([fromclause])
@_generative
def correlate(self, *fromclauses):
"""return a new select() construct which will correlate the given FROM
clauses to that of an enclosing select(), if a match is found.
By "match", the given fromclause must be present in this select's
list of FROM objects and also present in an enclosing select's list of
FROM objects.
Calling this method turns off the select's default behavior of
"auto-correlation". Normally, select() auto-correlates all of its FROM
clauses to those of an embedded select when compiled.
If the fromclause is None, correlation is disabled for the returned
select().
"""
self._should_correlate = False
if fromclauses == (None,):
self._correlate = set()
else:
self._correlate = self._correlate.union(fromclauses)
def append_correlation(self, fromclause):
"""append the given correlation expression to this select()
construct."""
self._should_correlate = False
self._correlate = self._correlate.union([fromclause])
def append_column(self, column):
"""append the given column expression to the columns clause of this
select() construct.
"""
column = _literal_as_column(column)
if isinstance(column, _ScalarSelect):
column = column.self_group(against=operators.comma_op)
self._raw_columns = self._raw_columns + [column]
self._froms = self._froms.union(_from_objects(column))
self._reset_exported()
def append_prefix(self, clause):
"""append the given columns clause prefix expression to this select()
construct.
"""
clause = _literal_as_text(clause)
self._prefixes = self._prefixes + (clause,)
def append_whereclause(self, whereclause):
"""append the given expression to this select() construct's WHERE
criterion.
The expression will be joined to existing WHERE criterion via AND.
"""
whereclause = _literal_as_text(whereclause)
self._froms = self._froms.union(_from_objects(whereclause))
if self._whereclause is not None:
self._whereclause = and_(self._whereclause, whereclause)
else:
self._whereclause = whereclause
def append_having(self, having):
"""append the given expression to this select() construct's HAVING
criterion.
The expression will be joined to existing HAVING criterion via AND.
"""
if self._having is not None:
self._having = and_(self._having, _literal_as_text(having))
else:
self._having = _literal_as_text(having)
def append_from(self, fromclause):
"""append the given FromClause expression to this select() construct's
FROM clause.
"""
if _is_literal(fromclause):
fromclause = _TextClause(fromclause)
self._froms = self._froms.union([fromclause])
def __exportable_columns(self):
for column in self._raw_columns:
if isinstance(column, Selectable):
for co in column.columns:
yield co
elif isinstance(column, ColumnElement):
yield column
else:
continue
def _populate_column_collection(self):
for c in self.__exportable_columns():
c._make_proxy(self, name=self.use_labels and c._label or None)
def self_group(self, against=None):
"""return a 'grouping' construct as per the ClauseElement
specification.
This produces an element that can be embedded in an expression. Note
that this method is called automatically as needed when constructing
expressions.
"""
if isinstance(against, CompoundSelect):
return self
return _FromGrouping(self)
def union(self, other, **kwargs):
"""return a SQL UNION of this select() construct against the given
selectable."""
return union(self, other, **kwargs)
def union_all(self, other, **kwargs):
"""return a SQL UNION ALL of this select() construct against the given
selectable.
"""
return union_all(self, other, **kwargs)
def except_(self, other, **kwargs):
"""return a SQL EXCEPT of this select() construct against the given
selectable."""
return except_(self, other, **kwargs)
def except_all(self, other, **kwargs):
"""return a SQL EXCEPT ALL of this select() construct against the
given selectable.
"""
return except_all(self, other, **kwargs)
def intersect(self, other, **kwargs):
"""return a SQL INTERSECT of this select() construct against the given
selectable.
"""
return intersect(self, other, **kwargs)
def intersect_all(self, other, **kwargs):
"""return a SQL INTERSECT ALL of this select() construct against the
given selectable.
"""
return intersect_all(self, other, **kwargs)
def bind(self):
if self._bind:
return self._bind
if not self._froms:
for c in self._raw_columns:
e = c.bind
if e:
self._bind = e
return e
else:
e = list(self._froms)[0].bind
if e:
self._bind = e
return e
return None
def _set_bind(self, bind):
self._bind = bind
bind = property(bind, _set_bind)
class _UpdateBase(Executable, ClauseElement):
"""Form the base for ``INSERT``, ``UPDATE``, and ``DELETE`` statements."""
__visit_name__ = 'update_base'
_execution_options = \
Executable._execution_options.union({'autocommit': True})
kwargs = util.frozendict()
def _process_colparams(self, parameters):
if isinstance(parameters, (list, tuple)):
pp = {}
for i, c in enumerate(self.table.c):
pp[c.key] = parameters[i]
return pp
else:
return parameters
def params(self, *arg, **kw):
raise NotImplementedError(
"params() is not supported for INSERT/UPDATE/DELETE statements."
" To set the values for an INSERT or UPDATE statement, use"
" stmt.values(**parameters).")
def bind(self):
return self._bind or self.table.bind
def _set_bind(self, bind):
self._bind = bind
bind = property(bind, _set_bind)
_returning_re = re.compile(r'(?:firebird|postgres(?:ql)?)_returning')
def _process_deprecated_kw(self, kwargs):
for k in list(kwargs):
m = self._returning_re.match(k)
if m:
self._returning = kwargs.pop(k)
util.warn_deprecated(
"The %r argument is deprecated. Please "
"use statement.returning(col1, col2, ...)" % k
)
return kwargs
@_generative
def returning(self, *cols):
"""Add a RETURNING or equivalent clause to this statement.
The given list of columns represent columns within the table that is
the target of the INSERT, UPDATE, or DELETE. Each element can be any
column expression. :class:`~sqlalchemy.schema.Table` objects will be
expanded into their individual columns.
Upon compilation, a RETURNING clause, or database equivalent,
will be rendered within the statement. For INSERT and UPDATE,
the values are the newly inserted/updated values. For DELETE,
the values are those of the rows which were deleted.
Upon execution, the values of the columns to be returned
are made available via the result set and can be iterated
using ``fetchone()`` and similar. For DBAPIs which do not
natively support returning values (i.e. cx_oracle),
SQLAlchemy will approximate this behavior at the result level
so that a reasonable amount of behavioral neutrality is
provided.
Note that not all databases/DBAPIs
support RETURNING. For those backends with no support,
an exception is raised upon compilation and/or execution.
For those who do support it, the functionality across backends
varies greatly, including restrictions on executemany()
and other statements which return multiple rows. Please
read the documentation notes for the database in use in
order to determine the availability of RETURNING.
"""
self._returning = cols
class _ValuesBase(_UpdateBase):
__visit_name__ = 'values_base'
def __init__(self, table, values):
self.table = table
self.parameters = self._process_colparams(values)
@_generative
def values(self, *args, **kwargs):
"""specify the VALUES clause for an INSERT statement, or the SET
clause for an UPDATE.
\**kwargs
key=<somevalue> arguments
\*args
A single dictionary can be sent as the first positional
argument. This allows non-string based keys, such as Column
objects, to be used.
"""
if args:
v = args[0]
else:
v = {}
if self.parameters is None:
self.parameters = self._process_colparams(v)
self.parameters.update(kwargs)
else:
self.parameters = self.parameters.copy()
self.parameters.update(self._process_colparams(v))
self.parameters.update(kwargs)
class Insert(_ValuesBase):
"""Represent an INSERT construct.
The :class:`Insert` object is created using the :func:`insert()` function.
"""
__visit_name__ = 'insert'
_prefixes = ()
def __init__(self,
table,
values=None,
inline=False,
bind=None,
prefixes=None,
returning=None,
**kwargs):
_ValuesBase.__init__(self, table, values)
self._bind = bind
self.select = None
self.inline = inline
self._returning = returning
if prefixes:
self._prefixes = tuple([_literal_as_text(p) for p in prefixes])
if kwargs:
self.kwargs = self._process_deprecated_kw(kwargs)
def get_children(self, **kwargs):
if self.select is not None:
return self.select,
else:
return ()
def _copy_internals(self, clone=_clone):
# TODO: coverage
self.parameters = self.parameters.copy()
@_generative
def prefix_with(self, clause):
"""Add a word or expression between INSERT and INTO. Generative.
If multiple prefixes are supplied, they will be separated with
spaces.
"""
clause = _literal_as_text(clause)
self._prefixes = self._prefixes + (clause,)
class Update(_ValuesBase):
"""Represent an Update construct.
The :class:`Update` object is created using the :func:`update()` function.
"""
__visit_name__ = 'update'
def __init__(self,
table,
whereclause,
values=None,
inline=False,
bind=None,
returning=None,
**kwargs):
_ValuesBase.__init__(self, table, values)
self._bind = bind
self._returning = returning
if whereclause is not None:
self._whereclause = _literal_as_text(whereclause)
else:
self._whereclause = None
self.inline = inline
if kwargs:
self.kwargs = self._process_deprecated_kw(kwargs)
def get_children(self, **kwargs):
if self._whereclause is not None:
return self._whereclause,
else:
return ()
def _copy_internals(self, clone=_clone):
# TODO: coverage
self._whereclause = clone(self._whereclause)
self.parameters = self.parameters.copy()
@_generative
def where(self, whereclause):
"""return a new update() construct with the given expression added to
its WHERE clause, joined to the existing clause via AND, if any.
"""
if self._whereclause is not None:
self._whereclause = and_(self._whereclause,
_literal_as_text(whereclause))
else:
self._whereclause = _literal_as_text(whereclause)
class Delete(_UpdateBase):
"""Represent a DELETE construct.
The :class:`Delete` object is created using the :func:`delete()` function.
"""
__visit_name__ = 'delete'
def __init__(self,
table,
whereclause,
bind=None,
returning =None,
**kwargs):
self._bind = bind
self.table = table
self._returning = returning
if whereclause is not None:
self._whereclause = _literal_as_text(whereclause)
else:
self._whereclause = None
if kwargs:
self.kwargs = self._process_deprecated_kw(kwargs)
def get_children(self, **kwargs):
if self._whereclause is not None:
return self._whereclause,
else:
return ()
@_generative
def where(self, whereclause):
"""Add the given WHERE clause to a newly returned delete construct."""
if self._whereclause is not None:
self._whereclause = and_(self._whereclause,
_literal_as_text(whereclause))
else:
self._whereclause = _literal_as_text(whereclause)
def _copy_internals(self, clone=_clone):
# TODO: coverage
self._whereclause = clone(self._whereclause)
class _IdentifiedClause(Executable, ClauseElement):
__visit_name__ = 'identified'
_execution_options = \
Executable._execution_options.union({'autocommit': False})
quote = None
def __init__(self, ident):
self.ident = ident
class SavepointClause(_IdentifiedClause):
__visit_name__ = 'savepoint'
class RollbackToSavepointClause(_IdentifiedClause):
__visit_name__ = 'rollback_to_savepoint'
class ReleaseSavepointClause(_IdentifiedClause):
__visit_name__ = 'release_savepoint'