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CouchPotatoServer/libs/sqlalchemy/orm/query.py

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# orm/query.py
# Copyright (C) 2005-2012 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
"""The Query class and support.
Defines the :class:`.Query` class, the central
construct used by the ORM to construct database queries.
The :class:`.Query` class should not be confused with the
:class:`.Select` class, which defines database
SELECT operations at the SQL (non-ORM) level. ``Query`` differs from
``Select`` in that it returns ORM-mapped objects and interacts with an
ORM session, whereas the ``Select`` construct interacts directly with the
database to return iterable result sets.
"""
from itertools import chain
from operator import itemgetter
from sqlalchemy import sql, util, log, schema
from sqlalchemy import exc as sa_exc
from sqlalchemy.orm import exc as orm_exc
from sqlalchemy.sql import util as sql_util
from sqlalchemy.sql import expression, visitors, operators
from sqlalchemy.orm import (
attributes, interfaces, mapper, object_mapper, evaluator,
)
from sqlalchemy.orm.util import (
AliasedClass, ORMAdapter, _entity_descriptor, _entity_info,
_is_aliased_class, _is_mapped_class, _orm_columns, _orm_selectable,
join as orm_join,with_parent, _attr_as_key, aliased
)
__all__ = ['Query', 'QueryContext', 'aliased']
def _generative(*assertions):
"""Mark a method as generative."""
@util.decorator
def generate(fn, *args, **kw):
self = args[0]._clone()
for assertion in assertions:
assertion(self, fn.func_name)
fn(self, *args[1:], **kw)
return self
return generate
class Query(object):
"""ORM-level SQL construction object.
:class:`.Query` is the source of all SELECT statements generated by the
ORM, both those formulated by end-user query operations as well as by
high level internal operations such as related collection loading. It
features a generative interface whereby successive calls return a new
:class:`.Query` object, a copy of the former with additional
criteria and options associated with it.
:class:`.Query` objects are normally initially generated using the
:meth:`~.Session.query` method of :class:`.Session`. For a full walkthrough
of :class:`.Query` usage, see the :ref:`ormtutorial_toplevel`.
"""
_enable_eagerloads = True
_enable_assertions = True
_with_labels = False
_criterion = None
_yield_per = None
_lockmode = None
_order_by = False
_group_by = False
_having = None
_distinct = False
_offset = None
_limit = None
_statement = None
_correlate = frozenset()
_populate_existing = False
_invoke_all_eagers = True
_version_check = False
_autoflush = True
_current_path = ()
_only_load_props = None
_refresh_state = None
_from_obj = ()
_join_entities = ()
_select_from_entity = None
_filter_aliases = None
_from_obj_alias = None
_joinpath = _joinpoint = util.immutabledict()
_execution_options = util.immutabledict()
_params = util.immutabledict()
_attributes = util.immutabledict()
_with_options = ()
_with_hints = ()
_enable_single_crit = True
def __init__(self, entities, session=None):
self.session = session
self._polymorphic_adapters = {}
self._set_entities(entities)
def _set_entities(self, entities, entity_wrapper=None):
if entity_wrapper is None:
entity_wrapper = _QueryEntity
self._entities = []
for ent in util.to_list(entities):
entity_wrapper(self, ent)
self._setup_aliasizers(self._entities)
def _setup_aliasizers(self, entities):
if hasattr(self, '_mapper_adapter_map'):
# usually safe to share a single map, but copying to prevent
# subtle leaks if end-user is reusing base query with arbitrary
# number of aliased() objects
self._mapper_adapter_map = d = self._mapper_adapter_map.copy()
else:
self._mapper_adapter_map = d = {}
for ent in entities:
for entity in ent.entities:
if entity not in d:
mapper, selectable, is_aliased_class = \
_entity_info(entity)
if not is_aliased_class and mapper.with_polymorphic:
with_polymorphic = mapper._with_polymorphic_mappers
if mapper.mapped_table not in \
self._polymorphic_adapters:
self._mapper_loads_polymorphically_with(mapper,
sql_util.ColumnAdapter(
selectable,
mapper._equivalent_columns))
adapter = None
elif is_aliased_class:
adapter = sql_util.ColumnAdapter(
selectable,
mapper._equivalent_columns)
with_polymorphic = None
else:
with_polymorphic = adapter = None
d[entity] = (mapper, adapter, selectable,
is_aliased_class, with_polymorphic)
ent.setup_entity(entity, *d[entity])
def _mapper_loads_polymorphically_with(self, mapper, adapter):
for m2 in mapper._with_polymorphic_mappers:
self._polymorphic_adapters[m2] = adapter
for m in m2.iterate_to_root():
self._polymorphic_adapters[m.mapped_table] = \
self._polymorphic_adapters[m.local_table] = \
adapter
def _set_select_from(self, *obj):
fa = []
for from_obj in obj:
if isinstance(from_obj, expression._SelectBase):
from_obj = from_obj.alias()
fa.append(from_obj)
self._from_obj = tuple(fa)
if len(self._from_obj) == 1 and \
isinstance(self._from_obj[0], expression.Alias):
equivs = self.__all_equivs()
self._from_obj_alias = sql_util.ColumnAdapter(
self._from_obj[0], equivs)
def _reset_polymorphic_adapter(self, mapper):
for m2 in mapper._with_polymorphic_mappers:
self._polymorphic_adapters.pop(m2, None)
for m in m2.iterate_to_root():
self._polymorphic_adapters.pop(m.mapped_table, None)
self._polymorphic_adapters.pop(m.local_table, None)
def __adapt_polymorphic_element(self, element):
if isinstance(element, expression.FromClause):
search = element
elif hasattr(element, 'table'):
search = element.table
else:
search = None
if search is not None:
alias = self._polymorphic_adapters.get(search, None)
if alias:
return alias.adapt_clause(element)
def _adapt_col_list(self, cols):
return [
self._adapt_clause(
expression._literal_as_text(o),
True, True)
for o in cols
]
@_generative()
def _adapt_all_clauses(self):
self._orm_only_adapt = False
def _adapt_clause(self, clause, as_filter, orm_only):
"""Adapt incoming clauses to transformations which have been applied
within this query."""
adapters = []
# do we adapt all expression elements or only those
# tagged as 'ORM' constructs ?
orm_only = getattr(self, '_orm_only_adapt', orm_only)
if as_filter and self._filter_aliases:
for fa in self._filter_aliases._visitor_iterator:
adapters.append(
(
orm_only, fa.replace
)
)
if self._from_obj_alias:
# for the "from obj" alias, apply extra rule to the
# 'ORM only' check, if this query were generated from a
# subquery of itself, i.e. _from_selectable(), apply adaption
# to all SQL constructs.
adapters.append(
(
getattr(self, '_orm_only_from_obj_alias', orm_only),
self._from_obj_alias.replace
)
)
if self._polymorphic_adapters:
adapters.append(
(
orm_only, self.__adapt_polymorphic_element
)
)
if not adapters:
return clause
def replace(elem):
for _orm_only, adapter in adapters:
# if 'orm only', look for ORM annotations
# in the element before adapting.
if not _orm_only or \
'_orm_adapt' in elem._annotations or \
"parententity" in elem._annotations:
e = adapter(elem)
if e is not None:
return e
return visitors.replacement_traverse(
clause,
{},
replace
)
def _entity_zero(self):
return self._entities[0]
def _mapper_zero(self):
return self._select_from_entity or \
self._entity_zero().entity_zero
@property
def _mapper_entities(self):
# TODO: this is wrong, its hardcoded to "primary entity" when
# for the case of __all_equivs() it should not be
# the name of this accessor is wrong too
for ent in self._entities:
if hasattr(ent, 'primary_entity'):
yield ent
def _joinpoint_zero(self):
return self._joinpoint.get(
'_joinpoint_entity',
self._mapper_zero()
)
def _mapper_zero_or_none(self):
if not getattr(self._entities[0], 'primary_entity', False):
return None
return self._entities[0].mapper
def _only_mapper_zero(self, rationale=None):
if len(self._entities) > 1:
raise sa_exc.InvalidRequestError(
rationale or
"This operation requires a Query against a single mapper."
)
return self._mapper_zero()
def _only_full_mapper_zero(self, methname):
if len(self._entities) != 1:
raise sa_exc.InvalidRequestError(
"%s() can only be used against "
"a single mapped class." % methname)
entity = self._entity_zero()
if not hasattr(entity, 'primary_entity'):
raise sa_exc.InvalidRequestError(
"%s() can only be used against "
"a single mapped class." % methname)
return entity.entity_zero
def _only_entity_zero(self, rationale=None):
if len(self._entities) > 1:
raise sa_exc.InvalidRequestError(
rationale or
"This operation requires a Query against a single mapper."
)
return self._entity_zero()
def __all_equivs(self):
equivs = {}
for ent in self._mapper_entities:
equivs.update(ent.mapper._equivalent_columns)
return equivs
def _get_condition(self):
self._order_by = self._distinct = False
return self._no_criterion_condition("get")
def _no_criterion_condition(self, meth):
if not self._enable_assertions:
return
if self._criterion is not None or \
self._statement is not None or self._from_obj or \
self._limit is not None or self._offset is not None or \
self._group_by or self._order_by or self._distinct:
raise sa_exc.InvalidRequestError(
"Query.%s() being called on a "
"Query with existing criterion. " % meth)
self._from_obj = ()
self._statement = self._criterion = None
self._order_by = self._group_by = self._distinct = False
def _no_clauseelement_condition(self, meth):
if not self._enable_assertions:
return
if self._order_by:
raise sa_exc.InvalidRequestError(
"Query.%s() being called on a "
"Query with existing criterion. " % meth)
self._no_criterion_condition(meth)
def _no_statement_condition(self, meth):
if not self._enable_assertions:
return
if self._statement is not None:
raise sa_exc.InvalidRequestError(
("Query.%s() being called on a Query with an existing full "
"statement - can't apply criterion.") % meth)
def _no_limit_offset(self, meth):
if not self._enable_assertions:
return
if self._limit is not None or self._offset is not None:
raise sa_exc.InvalidRequestError(
"Query.%s() being called on a Query which already has LIMIT "
"or OFFSET applied. To modify the row-limited results of a "
" Query, call from_self() first. "
"Otherwise, call %s() before limit() or offset() are applied."
% (meth, meth)
)
def _no_select_modifiers(self, meth):
if not self._enable_assertions:
return
for attr, methname, notset in (
('_limit', 'limit()', None),
('_offset', 'offset()', None),
('_order_by', 'order_by()', False),
('_group_by', 'group_by()', False),
('_distinct', 'distinct()', False),
):
if getattr(self, attr) is not notset:
raise sa_exc.InvalidRequestError(
"Can't call Query.%s() when %s has been called" %
(meth, methname)
)
def _get_options(self, populate_existing=None,
version_check=None,
only_load_props=None,
refresh_state=None):
if populate_existing:
self._populate_existing = populate_existing
if version_check:
self._version_check = version_check
if refresh_state:
self._refresh_state = refresh_state
if only_load_props:
self._only_load_props = set(only_load_props)
return self
def _clone(self):
cls = self.__class__
q = cls.__new__(cls)
q.__dict__ = self.__dict__.copy()
return q
@property
def statement(self):
"""The full SELECT statement represented by this Query.
The statement by default will not have disambiguating labels
applied to the construct unless with_labels(True) is called
first.
"""
stmt = self._compile_context(labels=self._with_labels).\
statement
if self._params:
stmt = stmt.params(self._params)
# TODO: there's no tests covering effects of
# the annotation not being there
return stmt._annotate({'no_replacement_traverse': True})
def subquery(self, name=None):
"""return the full SELECT statement represented by this :class:`.Query`,
embedded within an :class:`.Alias`.
Eager JOIN generation within the query is disabled.
The statement will not have disambiguating labels
applied to the list of selected columns unless the
:meth:`.Query.with_labels` method is used to generate a new
:class:`.Query` with the option enabled.
:param name: string name to be assigned as the alias;
this is passed through to :meth:`.FromClause.alias`.
If ``None``, a name will be deterministically generated
at compile time.
"""
return self.enable_eagerloads(False).statement.alias(name=name)
def cte(self, name=None, recursive=False):
"""Return the full SELECT statement represented by this :class:`.Query`
represented as a common table expression (CTE).
The :meth:`.Query.cte` method is new in 0.7.6.
Parameters and usage are the same as those of the
:meth:`._SelectBase.cte` method; see that method for
further details.
Here is the `Postgresql WITH
RECURSIVE example <http://www.postgresql.org/docs/8.4/static/queries-with.html>`_.
Note that, in this example, the ``included_parts`` cte and the ``incl_alias`` alias
of it are Core selectables, which
means the columns are accessed via the ``.c.`` attribute. The ``parts_alias``
object is an :func:`.orm.aliased` instance of the ``Part`` entity, so column-mapped
attributes are available directly::
from sqlalchemy.orm import aliased
class Part(Base):
__tablename__ = 'part'
part = Column(String, primary_key=True)
sub_part = Column(String, primary_key=True)
quantity = Column(Integer)
included_parts = session.query(
Part.sub_part,
Part.part,
Part.quantity).\\
filter(Part.part=="our part").\\
cte(name="included_parts", recursive=True)
incl_alias = aliased(included_parts, name="pr")
parts_alias = aliased(Part, name="p")
included_parts = included_parts.union_all(
session.query(
parts_alias.part,
parts_alias.sub_part,
parts_alias.quantity).\\
filter(parts_alias.part==incl_alias.c.sub_part)
)
q = session.query(
included_parts.c.sub_part,
func.sum(included_parts.c.quantity).label('total_quantity')
).\\
group_by(included_parts.c.sub_part)
See also:
:meth:`._SelectBase.cte`
"""
return self.enable_eagerloads(False).statement.cte(name=name, recursive=recursive)
def label(self, name):
"""Return the full SELECT statement represented by this :class:`.Query`, converted
to a scalar subquery with a label of the given name.
Analogous to :meth:`sqlalchemy.sql._SelectBaseMixin.label`.
New in 0.6.5.
"""
return self.enable_eagerloads(False).statement.label(name)
def as_scalar(self):
"""Return the full SELECT statement represented by this :class:`.Query`, converted
to a scalar subquery.
Analogous to :meth:`sqlalchemy.sql._SelectBaseMixin.as_scalar`.
New in 0.6.5.
"""
return self.enable_eagerloads(False).statement.as_scalar()
def __clause_element__(self):
return self.enable_eagerloads(False).with_labels().statement
@_generative()
def enable_eagerloads(self, value):
"""Control whether or not eager joins and subqueries are
rendered.
When set to False, the returned Query will not render
eager joins regardless of :func:`~sqlalchemy.orm.joinedload`,
:func:`~sqlalchemy.orm.subqueryload` options
or mapper-level ``lazy='joined'``/``lazy='subquery'``
configurations.
This is used primarily when nesting the Query's
statement into a subquery or other
selectable.
"""
self._enable_eagerloads = value
@_generative()
def with_labels(self):
"""Apply column labels to the return value of Query.statement.
Indicates that this Query's `statement` accessor should return
a SELECT statement that applies labels to all columns in the
form <tablename>_<columnname>; this is commonly used to
disambiguate columns from multiple tables which have the same
name.
When the `Query` actually issues SQL to load rows, it always
uses column labeling.
"""
self._with_labels = True
@_generative()
def enable_assertions(self, value):
"""Control whether assertions are generated.
When set to False, the returned Query will
not assert its state before certain operations,
including that LIMIT/OFFSET has not been applied
when filter() is called, no criterion exists
when get() is called, and no "from_statement()"
exists when filter()/order_by()/group_by() etc.
is called. This more permissive mode is used by
custom Query subclasses to specify criterion or
other modifiers outside of the usual usage patterns.
Care should be taken to ensure that the usage
pattern is even possible. A statement applied
by from_statement() will override any criterion
set by filter() or order_by(), for example.
"""
self._enable_assertions = value
@property
def whereclause(self):
"""A readonly attribute which returns the current WHERE criterion for this Query.
This returned value is a SQL expression construct, or ``None`` if no
criterion has been established.
"""
return self._criterion
@_generative()
def _with_current_path(self, path):
"""indicate that this query applies to objects loaded
within a certain path.
Used by deferred loaders (see strategies.py) which transfer
query options from an originating query to a newly generated
query intended for the deferred load.
"""
self._current_path = path
@_generative(_no_clauseelement_condition)
def with_polymorphic(self,
cls_or_mappers,
selectable=None, discriminator=None):
"""Load columns for descendant mappers of this Query's mapper.
Using this method will ensure that each descendant mapper's
tables are included in the FROM clause, and will allow filter()
criterion to be used against those tables. The resulting
instances will also have those columns already loaded so that
no "post fetch" of those columns will be required.
:param cls_or_mappers: a single class or mapper, or list of
class/mappers, which inherit from this Query's mapper.
Alternatively, it may also be the string ``'*'``, in which case
all descending mappers will be added to the FROM clause.
:param selectable: a table or select() statement that will
be used in place of the generated FROM clause. This argument is
required if any of the desired mappers use concrete table
inheritance, since SQLAlchemy currently cannot generate UNIONs
among tables automatically. If used, the ``selectable`` argument
must represent the full set of tables and columns mapped by every
desired mapper. Otherwise, the unaccounted mapped columns will
result in their table being appended directly to the FROM clause
which will usually lead to incorrect results.
:param discriminator: a column to be used as the "discriminator"
column for the given selectable. If not given, the polymorphic_on
attribute of the mapper will be used, if any. This is useful for
mappers that don't have polymorphic loading behavior by default,
such as concrete table mappers.
"""
if not getattr(self._entities[0], 'primary_entity', False):
raise sa_exc.InvalidRequestError(
"No primary mapper set up for this Query.")
entity = self._entities[0]._clone()
self._entities = [entity] + self._entities[1:]
entity.set_with_polymorphic(self,
cls_or_mappers,
selectable=selectable,
discriminator=discriminator)
@_generative()
def yield_per(self, count):
"""Yield only ``count`` rows at a time.
WARNING: use this method with caution; if the same instance is present
in more than one batch of rows, end-user changes to attributes will be
overwritten.
In particular, it's usually impossible to use this setting with
eagerly loaded collections (i.e. any lazy='joined' or 'subquery')
since those collections will be cleared for a new load when
encountered in a subsequent result batch. In the case of 'subquery'
loading, the full result for all rows is fetched which generally
defeats the purpose of :meth:`~sqlalchemy.orm.query.Query.yield_per`.
Also note that many DBAPIs do not "stream" results, pre-buffering
all rows before making them available, including mysql-python and
psycopg2. :meth:`~sqlalchemy.orm.query.Query.yield_per` will also
set the ``stream_results`` execution
option to ``True``, which currently is only understood by psycopg2
and causes server side cursors to be used.
"""
self._yield_per = count
self._execution_options = self._execution_options.copy()
self._execution_options['stream_results'] = True
def get(self, ident):
"""Return an instance based on the given primary key identifier,
or ``None`` if not found.
E.g.::
my_user = session.query(User).get(5)
some_object = session.query(VersionedFoo).get((5, 10))
:meth:`~.Query.get` is special in that it provides direct
access to the identity map of the owning :class:`.Session`.
If the given primary key identifier is present
in the local identity map, the object is returned
directly from this collection and no SQL is emitted,
unless the object has been marked fully expired.
If not present,
a SELECT is performed in order to locate the object.
:meth:`~.Query.get` also will perform a check if
the object is present in the identity map and
marked as expired - a SELECT
is emitted to refresh the object as well as to
ensure that the row is still present.
If not, :class:`~sqlalchemy.orm.exc.ObjectDeletedError` is raised.
:meth:`~.Query.get` is only used to return a single
mapped instance, not multiple instances or
individual column constructs, and strictly
on a single primary key value. The originating
:class:`.Query` must be constructed in this way,
i.e. against a single mapped entity,
with no additional filtering criterion. Loading
options via :meth:`~.Query.options` may be applied
however, and will be used if the object is not
yet locally present.
A lazy-loading, many-to-one attribute configured
by :func:`.relationship`, using a simple
foreign-key-to-primary-key criterion, will also use an
operation equivalent to :meth:`~.Query.get` in order to retrieve
the target value from the local identity map
before querying the database. See :ref:`loading_toplevel`
for further details on relationship loading.
:param ident: A scalar or tuple value representing
the primary key. For a composite primary key,
the order of identifiers corresponds in most cases
to that of the mapped :class:`.Table` object's
primary key columns. For a :func:`.mapper` that
was given the ``primary key`` argument during
construction, the order of identifiers corresponds
to the elements present in this collection.
:return: The object instance, or ``None``.
"""
# convert composite types to individual args
if hasattr(ident, '__composite_values__'):
ident = ident.__composite_values__()
ident = util.to_list(ident)
mapper = self._only_full_mapper_zero("get")
if len(ident) != len(mapper.primary_key):
raise sa_exc.InvalidRequestError(
"Incorrect number of values in identifier to formulate "
"primary key for query.get(); primary key columns are %s" %
','.join("'%s'" % c for c in mapper.primary_key))
key = mapper.identity_key_from_primary_key(ident)
if not self._populate_existing and \
not mapper.always_refresh and \
self._lockmode is None:
instance = self._get_from_identity(self.session, key, False)
if instance is not None:
# reject calls for id in identity map but class
# mismatch.
if not issubclass(instance.__class__, mapper.class_):
return None
return instance
return self._load_on_ident(key)
@_generative()
def correlate(self, *args):
"""Return a :class:`.Query` construct which will correlate the given
FROM clauses to that of an enclosing :class:`.Query` or
:func:`~.expression.select`.
The method here accepts mapped classes, :func:`.aliased` constructs,
and :func:`.mapper` constructs as arguments, which are resolved into
expression constructs, in addition to appropriate expression
constructs.
The correlation arguments are ultimately passed to
:meth:`.Select.correlate` after coercion to expression constructs.
The correlation arguments take effect in such cases
as when :meth:`.Query.from_self` is used, or when
a subquery as returned by :meth:`.Query.subquery` is
embedded in another :func:`~.expression.select` construct.
"""
self._correlate = self._correlate.union(
_orm_selectable(s)
for s in args)
@_generative()
def autoflush(self, setting):
"""Return a Query with a specific 'autoflush' setting.
Note that a Session with autoflush=False will
not autoflush, even if this flag is set to True at the
Query level. Therefore this flag is usually used only
to disable autoflush for a specific Query.
"""
self._autoflush = setting
@_generative()
def populate_existing(self):
"""Return a :class:`.Query` that will expire and refresh all instances
as they are loaded, or reused from the current :class:`.Session`.
:meth:`.populate_existing` does not improve behavior when
the ORM is used normally - the :class:`.Session` object's usual
behavior of maintaining a transaction and expiring all attributes
after rollback or commit handles object state automatically.
This method is not intended for general use.
"""
self._populate_existing = True
@_generative()
def _with_invoke_all_eagers(self, value):
"""Set the 'invoke all eagers' flag which causes joined- and
subquery loaders to traverse into already-loaded related objects
and collections.
Default is that of :attr:`.Query._invoke_all_eagers`.
"""
self._invoke_all_eagers = value
def with_parent(self, instance, property=None):
"""Add filtering criterion that relates the given instance
to a child object or collection, using its attribute state
as well as an established :func:`.relationship()`
configuration.
The method uses the :func:`.with_parent` function to generate
the clause, the result of which is passed to :meth:`.Query.filter`.
Parameters are the same as :func:`.with_parent`, with the exception
that the given property can be None, in which case a search is
performed against this :class:`.Query` object's target mapper.
"""
if property is None:
from sqlalchemy.orm import properties
mapper = object_mapper(instance)
for prop in mapper.iterate_properties:
if isinstance(prop, properties.PropertyLoader) and \
prop.mapper is self._mapper_zero():
property = prop
break
else:
raise sa_exc.InvalidRequestError(
"Could not locate a property which relates instances "
"of class '%s' to instances of class '%s'" %
(
self._mapper_zero().class_.__name__,
instance.__class__.__name__)
)
return self.filter(with_parent(instance, property))
@_generative()
def add_entity(self, entity, alias=None):
"""add a mapped entity to the list of result columns
to be returned."""
if alias is not None:
entity = aliased(entity, alias)
self._entities = list(self._entities)
m = _MapperEntity(self, entity)
self._setup_aliasizers([m])
@_generative()
def with_session(self, session):
"""Return a :class:`Query` that will use the given :class:`.Session`.
"""
self.session = session
def from_self(self, *entities):
"""return a Query that selects from this Query's
SELECT statement.
\*entities - optional list of entities which will replace
those being selected.
"""
fromclause = self.with_labels().enable_eagerloads(False).\
_enable_single_crit(False).\
statement.correlate(None)
q = self._from_selectable(fromclause)
if entities:
q._set_entities(entities)
return q
@_generative()
def _enable_single_crit(self, val):
self._enable_single_crit = val
@_generative()
def _from_selectable(self, fromclause):
for attr in (
'_statement', '_criterion',
'_order_by', '_group_by',
'_limit', '_offset',
'_joinpath', '_joinpoint',
'_distinct', '_having'
):
self.__dict__.pop(attr, None)
self._set_select_from(fromclause)
# this enables clause adaptation for non-ORM
# expressions.
self._orm_only_from_obj_alias = False
old_entities = self._entities
self._entities = []
for e in old_entities:
e.adapt_to_selectable(self, self._from_obj[0])
def values(self, *columns):
"""Return an iterator yielding result tuples corresponding
to the given list of columns"""
if not columns:
return iter(())
q = self._clone()
q._set_entities(columns, entity_wrapper=_ColumnEntity)
if not q._yield_per:
q._yield_per = 10
return iter(q)
_values = values
def value(self, column):
"""Return a scalar result corresponding to the given
column expression."""
try:
# Py3K
#return self.values(column).__next__()[0]
# Py2K
return self.values(column).next()[0]
# end Py2K
except StopIteration:
return None
@_generative()
def with_entities(self, *entities):
"""Return a new :class:`.Query` replacing the SELECT list with the given
entities.
e.g.::
# Users, filtered on some arbitrary criterion
# and then ordered by related email address
q = session.query(User).\\
join(User.address).\\
filter(User.name.like('%ed%')).\\
order_by(Address.email)
# given *only* User.id==5, Address.email, and 'q', what
# would the *next* User in the result be ?
subq = q.with_entities(Address.email).\\
order_by(None).\\
filter(User.id==5).\\
subquery()
q = q.join((subq, subq.c.email < Address.email)).\\
limit(1)
New in 0.6.5.
"""
self._set_entities(entities)
@_generative()
def add_columns(self, *column):
"""Add one or more column expressions to the list
of result columns to be returned."""
self._entities = list(self._entities)
l = len(self._entities)
for c in column:
_ColumnEntity(self, c)
# _ColumnEntity may add many entities if the
# given arg is a FROM clause
self._setup_aliasizers(self._entities[l:])
@util.pending_deprecation("0.7",
":meth:`.add_column` is superseded by :meth:`.add_columns`",
False)
def add_column(self, column):
"""Add a column expression to the list of result columns to be returned.
Pending deprecation: :meth:`.add_column` will be superseded by
:meth:`.add_columns`.
"""
return self.add_columns(column)
def options(self, *args):
"""Return a new Query object, applying the given list of
mapper options.
Most supplied options regard changing how column- and
relationship-mapped attributes are loaded. See the sections
:ref:`deferred` and :ref:`loading_toplevel` for reference
documentation.
"""
return self._options(False, *args)
def _conditional_options(self, *args):
return self._options(True, *args)
@_generative()
def _options(self, conditional, *args):
# most MapperOptions write to the '_attributes' dictionary,
# so copy that as well
self._attributes = self._attributes.copy()
opts = tuple(util.flatten_iterator(args))
self._with_options = self._with_options + opts
if conditional:
for opt in opts:
opt.process_query_conditionally(self)
else:
for opt in opts:
opt.process_query(self)
def with_transformation(self, fn):
"""Return a new :class:`.Query` object transformed by
the given function.
E.g.::
def filter_something(criterion):
def transform(q):
return q.filter(criterion)
return transform
q = q.with_transformation(filter_something(x==5))
This allows ad-hoc recipes to be created for :class:`.Query`
objects. See the example at :ref:`hybrid_transformers`.
:meth:`~.Query.with_transformation` is new in SQLAlchemy 0.7.4.
"""
return fn(self)
@_generative()
def with_hint(self, selectable, text, dialect_name='*'):
"""Add an indexing hint for the given entity or selectable to
this :class:`.Query`.
Functionality is passed straight through to
:meth:`~sqlalchemy.sql.expression.Select.with_hint`,
with the addition that ``selectable`` can be a
:class:`.Table`, :class:`.Alias`, or ORM entity / mapped class
/etc.
"""
mapper, selectable, is_aliased_class = _entity_info(selectable)
self._with_hints += ((selectable, text, dialect_name),)
@_generative()
def execution_options(self, **kwargs):
""" Set non-SQL options which take effect during execution.
The options are the same as those accepted by
:meth:`.Connection.execution_options`.
Note that the ``stream_results`` execution option is enabled
automatically if the :meth:`~sqlalchemy.orm.query.Query.yield_per()`
method is used.
"""
self._execution_options = self._execution_options.union(kwargs)
@_generative()
def with_lockmode(self, mode):
"""Return a new Query object with the specified locking mode.
:param mode: a string representing the desired locking mode. A
corresponding value is passed to the ``for_update`` parameter of
:meth:`~sqlalchemy.sql.expression.select` when the query is
executed. Valid values are:
``'update'`` - passes ``for_update=True``, which translates to
``FOR UPDATE`` (standard SQL, supported by most dialects)
``'update_nowait'`` - passes ``for_update='nowait'``, which
translates to ``FOR UPDATE NOWAIT`` (supported by Oracle)
``'read'`` - passes ``for_update='read'``, which translates to
``LOCK IN SHARE MODE`` (supported by MySQL).
"""
self._lockmode = mode
@_generative()
def params(self, *args, **kwargs):
"""add values for bind parameters which may have been
specified in filter().
parameters may be specified using \**kwargs, or optionally a single
dictionary as the first positional argument. The reason for both is
that \**kwargs is convenient, however some parameter dictionaries
contain unicode keys in which case \**kwargs cannot be used.
"""
if len(args) == 1:
kwargs.update(args[0])
elif len(args) > 0:
raise sa_exc.ArgumentError(
"params() takes zero or one positional argument, "
"which is a dictionary.")
self._params = self._params.copy()
self._params.update(kwargs)
@_generative(_no_statement_condition, _no_limit_offset)
def filter(self, *criterion):
"""apply the given filtering criterion to a copy
of this :class:`.Query`, using SQL expressions.
e.g.::
session.query(MyClass).filter(MyClass.name == 'some name')
Multiple criteria are joined together by AND (new in 0.7.5)::
session.query(MyClass).\\
filter(MyClass.name == 'some name', MyClass.id > 5)
The criterion is any SQL expression object applicable to the
WHERE clause of a select. String expressions are coerced
into SQL expression constructs via the :func:`.text` construct.
See also:
:meth:`.Query.filter_by` - filter on keyword expressions.
"""
for criterion in list(criterion):
if isinstance(criterion, basestring):
criterion = sql.text(criterion)
if criterion is not None and \
not isinstance(criterion, sql.ClauseElement):
raise sa_exc.ArgumentError(
"filter() argument must be of type "
"sqlalchemy.sql.ClauseElement or string")
criterion = self._adapt_clause(criterion, True, True)
if self._criterion is not None:
self._criterion = self._criterion & criterion
else:
self._criterion = criterion
def filter_by(self, **kwargs):
"""apply the given filtering criterion to a copy
of this :class:`.Query`, using keyword expressions.
e.g.::
session.query(MyClass).filter_by(name = 'some name')
Multiple criteria are joined together by AND::
session.query(MyClass).\\
filter_by(name = 'some name', id = 5)
The keyword expressions are extracted from the primary
entity of the query, or the last entity that was the
target of a call to :meth:`.Query.join`.
See also:
:meth:`.Query.filter` - filter on SQL expressions.
"""
clauses = [_entity_descriptor(self._joinpoint_zero(), key) == value
for key, value in kwargs.iteritems()]
return self.filter(sql.and_(*clauses))
@_generative(_no_statement_condition, _no_limit_offset)
def order_by(self, *criterion):
"""apply one or more ORDER BY criterion to the query and return
the newly resulting ``Query``
All existing ORDER BY settings can be suppressed by
passing ``None`` - this will suppress any ORDER BY configured
on mappers as well.
Alternatively, an existing ORDER BY setting on the Query
object can be entirely cancelled by passing ``False``
as the value - use this before calling methods where
an ORDER BY is invalid.
"""
if len(criterion) == 1:
if criterion[0] is False:
if '_order_by' in self.__dict__:
del self._order_by
return
if criterion[0] is None:
self._order_by = None
return
criterion = self._adapt_col_list(criterion)
if self._order_by is False or self._order_by is None:
self._order_by = criterion
else:
self._order_by = self._order_by + criterion
@_generative(_no_statement_condition, _no_limit_offset)
def group_by(self, *criterion):
"""apply one or more GROUP BY criterion to the query and return
the newly resulting ``Query``"""
criterion = list(chain(*[_orm_columns(c) for c in criterion]))
criterion = self._adapt_col_list(criterion)
if self._group_by is False:
self._group_by = criterion
else:
self._group_by = self._group_by + criterion
@_generative(_no_statement_condition, _no_limit_offset)
def having(self, criterion):
"""apply a HAVING criterion to the query and return the
newly resulting ``Query``."""
if isinstance(criterion, basestring):
criterion = sql.text(criterion)
if criterion is not None and \
not isinstance(criterion, sql.ClauseElement):
raise sa_exc.ArgumentError(
"having() argument must be of type "
"sqlalchemy.sql.ClauseElement or string")
criterion = self._adapt_clause(criterion, True, True)
if self._having is not None:
self._having = self._having & criterion
else:
self._having = criterion
def union(self, *q):
"""Produce a UNION of this Query against one or more queries.
e.g.::
q1 = sess.query(SomeClass).filter(SomeClass.foo=='bar')
q2 = sess.query(SomeClass).filter(SomeClass.bar=='foo')
q3 = q1.union(q2)
The method accepts multiple Query objects so as to control
the level of nesting. A series of ``union()`` calls such as::
x.union(y).union(z).all()
will nest on each ``union()``, and produces::
SELECT * FROM (SELECT * FROM (SELECT * FROM X UNION
SELECT * FROM y) UNION SELECT * FROM Z)
Whereas::
x.union(y, z).all()
produces::
SELECT * FROM (SELECT * FROM X UNION SELECT * FROM y UNION
SELECT * FROM Z)
Note that many database backends do not allow ORDER BY to
be rendered on a query called within UNION, EXCEPT, etc.
To disable all ORDER BY clauses including those configured
on mappers, issue ``query.order_by(None)`` - the resulting
:class:`.Query` object will not render ORDER BY within
its SELECT statement.
"""
return self._from_selectable(
expression.union(*([self]+ list(q))))
def union_all(self, *q):
"""Produce a UNION ALL of this Query against one or more queries.
Works the same way as :meth:`~sqlalchemy.orm.query.Query.union`. See
that method for usage examples.
"""
return self._from_selectable(
expression.union_all(*([self]+ list(q)))
)
def intersect(self, *q):
"""Produce an INTERSECT of this Query against one or more queries.
Works the same way as :meth:`~sqlalchemy.orm.query.Query.union`. See
that method for usage examples.
"""
return self._from_selectable(
expression.intersect(*([self]+ list(q)))
)
def intersect_all(self, *q):
"""Produce an INTERSECT ALL of this Query against one or more queries.
Works the same way as :meth:`~sqlalchemy.orm.query.Query.union`. See
that method for usage examples.
"""
return self._from_selectable(
expression.intersect_all(*([self]+ list(q)))
)
def except_(self, *q):
"""Produce an EXCEPT of this Query against one or more queries.
Works the same way as :meth:`~sqlalchemy.orm.query.Query.union`. See
that method for usage examples.
"""
return self._from_selectable(
expression.except_(*([self]+ list(q)))
)
def except_all(self, *q):
"""Produce an EXCEPT ALL of this Query against one or more queries.
Works the same way as :meth:`~sqlalchemy.orm.query.Query.union`. See
that method for usage examples.
"""
return self._from_selectable(
expression.except_all(*([self]+ list(q)))
)
def join(self, *props, **kwargs):
"""Create a SQL JOIN against this :class:`.Query` object's criterion
and apply generatively, returning the newly resulting :class:`.Query`.
**Simple Relationship Joins**
Consider a mapping between two classes ``User`` and ``Address``,
with a relationship ``User.addresses`` representing a collection
of ``Address`` objects associated with each ``User``. The most common
usage of :meth:`~.Query.join` is to create a JOIN along this
relationship, using the ``User.addresses`` attribute as an indicator
for how this should occur::
q = session.query(User).join(User.addresses)
Where above, the call to :meth:`~.Query.join` along ``User.addresses``
will result in SQL equivalent to::
SELECT user.* FROM user JOIN address ON user.id = address.user_id
In the above example we refer to ``User.addresses`` as passed to
:meth:`~.Query.join` as the *on clause*, that is, it indicates
how the "ON" portion of the JOIN should be constructed. For a
single-entity query such as the one above (i.e. we start by selecting only from
``User`` and nothing else), the relationship can also be specified by its
string name::
q = session.query(User).join("addresses")
:meth:`~.Query.join` can also accommodate multiple
"on clause" arguments to produce a chain of joins, such as below
where a join across four related entities is constructed::
q = session.query(User).join("orders", "items", "keywords")
The above would be shorthand for three separate calls to :meth:`~.Query.join`,
each using an explicit attribute to indicate the source entity::
q = session.query(User).\\
join(User.orders).\\
join(Order.items).\\
join(Item.keywords)
**Joins to a Target Entity or Selectable**
A second form of :meth:`~.Query.join` allows any mapped entity
or core selectable construct as a target. In this usage,
:meth:`~.Query.join` will attempt
to create a JOIN along the natural foreign key relationship between
two entities::
q = session.query(User).join(Address)
The above calling form of :meth:`.join` will raise an error if
either there are no foreign keys between the two entities, or if
there are multiple foreign key linkages between them. In the
above calling form, :meth:`~.Query.join` is called upon to
create the "on clause" automatically for us. The target can
be any mapped entity or selectable, such as a :class:`.Table`::
q = session.query(User).join(addresses_table)
**Joins to a Target with an ON Clause**
The third calling form allows both the target entity as well
as the ON clause to be passed explicitly. Suppose for
example we wanted to join to ``Address`` twice, using
an alias the second time. We use :func:`~sqlalchemy.orm.aliased`
to create a distinct alias of ``Address``, and join
to it using the ``target, onclause`` form, so that the
alias can be specified explicitly as the target along with
the relationship to instruct how the ON clause should proceed::
a_alias = aliased(Address)
q = session.query(User).\\
join(User.addresses).\\
join(a_alias, User.addresses).\\
filter(Address.email_address=='ed@foo.com').\\
filter(a_alias.email_address=='ed@bar.com')
Where above, the generated SQL would be similar to::
SELECT user.* FROM user
JOIN address ON user.id = address.user_id
JOIN address AS address_1 ON user.id=address_1.user_id
WHERE address.email_address = :email_address_1
AND address_1.email_address = :email_address_2
The two-argument calling form of :meth:`~.Query.join`
also allows us to construct arbitrary joins with SQL-oriented
"on clause" expressions, not relying upon configured relationships
at all. Any SQL expression can be passed as the ON clause
when using the two-argument form, which should refer to the target
entity in some way as well as an applicable source entity::
q = session.query(User).join(Address, User.id==Address.user_id)
.. note::
In SQLAlchemy 0.6 and earlier, the two argument form of
:meth:`~.Query.join` requires the usage of a tuple::
query(User).join((Address, User.id==Address.user_id))
This calling form is accepted in 0.7 and further, though
is not necessary unless multiple join conditions are passed to
a single :meth:`~.Query.join` call, which itself is also not
generally necessary as it is now equivalent to multiple
calls (this wasn't always the case).
**Advanced Join Targeting and Adaption**
There is a lot of flexibility in what the "target" can be when using
:meth:`~.Query.join`. As noted previously, it also accepts
:class:`.Table` constructs and other selectables such as :func:`.alias`
and :func:`.select` constructs, with either the one or two-argument forms::
addresses_q = select([Address.user_id]).\\
filter(Address.email_address.endswith("@bar.com")).\\
alias()
q = session.query(User).\\
join(addresses_q, addresses_q.c.user_id==User.id)
:meth:`~.Query.join` also features the ability to *adapt* a
:meth:`~sqlalchemy.orm.relationship` -driven ON clause to the target selectable.
Below we construct a JOIN from ``User`` to a subquery against ``Address``, allowing
the relationship denoted by ``User.addresses`` to *adapt* itself
to the altered target::
address_subq = session.query(Address).\\
filter(Address.email_address == 'ed@foo.com').\\
subquery()
q = session.query(User).join(address_subq, User.addresses)
Producing SQL similar to::
SELECT user.* FROM user
JOIN (
SELECT address.id AS id,
address.user_id AS user_id,
address.email_address AS email_address
FROM address
WHERE address.email_address = :email_address_1
) AS anon_1 ON user.id = anon_1.user_id
The above form allows one to fall back onto an explicit ON
clause at any time::
q = session.query(User).\\
join(address_subq, User.id==address_subq.c.user_id)
**Controlling what to Join From**
While :meth:`~.Query.join` exclusively deals with the "right"
side of the JOIN, we can also control the "left" side, in those
cases where it's needed, using :meth:`~.Query.select_from`.
Below we construct a query against ``Address`` but can still
make usage of ``User.addresses`` as our ON clause by instructing
the :class:`.Query` to select first from the ``User``
entity::
q = session.query(Address).select_from(User).\\
join(User.addresses).\\
filter(User.name == 'ed')
Which will produce SQL similar to::
SELECT address.* FROM user
JOIN address ON user.id=address.user_id
WHERE user.name = :name_1
**Constructing Aliases Anonymously**
:meth:`~.Query.join` can construct anonymous aliases
using the ``aliased=True`` flag. This feature is useful
when a query is being joined algorithmically, such as
when querying self-referentially to an arbitrary depth::
q = session.query(Node).\\
join("children", "children", aliased=True)
When ``aliased=True`` is used, the actual "alias" construct
is not explicitly available. To work with it, methods such as
:meth:`.Query.filter` will adapt the incoming entity to
the last join point::
q = session.query(Node).\\
join("children", "children", aliased=True).\\
filter(Node.name == 'grandchild 1')
When using automatic aliasing, the ``from_joinpoint=True``
argument can allow a multi-node join to be broken into
multiple calls to :meth:`~.Query.join`, so that
each path along the way can be further filtered::
q = session.query(Node).\\
join("children", aliased=True).\\
filter(Node.name='child 1').\\
join("children", aliased=True, from_joinpoint=True).\\
filter(Node.name == 'grandchild 1')
The filtering aliases above can then be reset back to the
original ``Node`` entity using :meth:`~.Query.reset_joinpoint`::
q = session.query(Node).\\
join("children", "children", aliased=True).\\
filter(Node.name == 'grandchild 1').\\
reset_joinpoint().\\
filter(Node.name == 'parent 1)
For an example of ``aliased=True``, see the distribution
example :ref:`examples_xmlpersistence` which illustrates
an XPath-like query system using algorithmic joins.
:param *props: A collection of one or more join conditions,
each consisting of a relationship-bound attribute or string
relationship name representing an "on clause", or a single
target entity, or a tuple in the form of ``(target, onclause)``.
A special two-argument calling form of the form ``target, onclause``
is also accepted.
:param aliased=False: If True, indicate that the JOIN target should be
anonymously aliased. Subsequent calls to :class:`~.Query.filter`
and similar will adapt the incoming criterion to the target
alias, until :meth:`~.Query.reset_joinpoint` is called.
:param from_joinpoint=False: When using ``aliased=True``, a setting
of True here will cause the join to be from the most recent
joined target, rather than starting back from the original
FROM clauses of the query.
See also:
:ref:`ormtutorial_joins` in the ORM tutorial.
:ref:`inheritance_toplevel` for details on how :meth:`~.Query.join`
is used for inheritance relationships.
:func:`.orm.join` - a standalone ORM-level join function,
used internally by :meth:`.Query.join`, which in previous
SQLAlchemy versions was the primary ORM-level joining interface.
"""
aliased, from_joinpoint = kwargs.pop('aliased', False),\
kwargs.pop('from_joinpoint', False)
if kwargs:
raise TypeError("unknown arguments: %s" %
','.join(kwargs.iterkeys()))
return self._join(props,
outerjoin=False, create_aliases=aliased,
from_joinpoint=from_joinpoint)
def outerjoin(self, *props, **kwargs):
"""Create a left outer join against this ``Query`` object's criterion
and apply generatively, returning the newly resulting ``Query``.
Usage is the same as the ``join()`` method.
"""
aliased, from_joinpoint = kwargs.pop('aliased', False), \
kwargs.pop('from_joinpoint', False)
if kwargs:
raise TypeError("unknown arguments: %s" %
','.join(kwargs.iterkeys()))
return self._join(props,
outerjoin=True, create_aliases=aliased,
from_joinpoint=from_joinpoint)
def _update_joinpoint(self, jp):
self._joinpoint = jp
# copy backwards to the root of the _joinpath
# dict, so that no existing dict in the path is mutated
while 'prev' in jp:
f, prev = jp['prev']
prev = prev.copy()
prev[f] = jp
jp['prev'] = (f, prev)
jp = prev
self._joinpath = jp
@_generative(_no_statement_condition, _no_limit_offset)
def _join(self, keys, outerjoin, create_aliases, from_joinpoint):
"""consumes arguments from join() or outerjoin(), places them into a
consistent format with which to form the actual JOIN constructs.
"""
if not from_joinpoint:
self._reset_joinpoint()
if len(keys) == 2 and \
isinstance(keys[0], (expression.FromClause,
type, AliasedClass)) and \
isinstance(keys[1], (basestring, expression.ClauseElement,
interfaces.PropComparator)):
# detect 2-arg form of join and
# convert to a tuple.
keys = (keys,)
for arg1 in util.to_list(keys):
if isinstance(arg1, tuple):
# "tuple" form of join, multiple
# tuples are accepted as well. The simpler
# "2-arg" form is preferred. May deprecate
# the "tuple" usage.
arg1, arg2 = arg1
else:
arg2 = None
# determine onclause/right_entity. there
# is a little bit of legacy behavior still at work here
# which means they might be in either order. may possibly
# lock this down to (right_entity, onclause) in 0.6.
if isinstance(arg1, (interfaces.PropComparator, basestring)):
right_entity, onclause = arg2, arg1
else:
right_entity, onclause = arg1, arg2
left_entity = prop = None
if isinstance(onclause, basestring):
left_entity = self._joinpoint_zero()
descriptor = _entity_descriptor(left_entity, onclause)
onclause = descriptor
# check for q.join(Class.propname, from_joinpoint=True)
# and Class is that of the current joinpoint
elif from_joinpoint and \
isinstance(onclause, interfaces.PropComparator):
left_entity = onclause.parententity
left_mapper, left_selectable, left_is_aliased = \
_entity_info(self._joinpoint_zero())
if left_mapper is left_entity:
left_entity = self._joinpoint_zero()
descriptor = _entity_descriptor(left_entity,
onclause.key)
onclause = descriptor
if isinstance(onclause, interfaces.PropComparator):
if right_entity is None:
right_entity = onclause.property.mapper
of_type = getattr(onclause, '_of_type', None)
if of_type:
right_entity = of_type
else:
right_entity = onclause.property.mapper
left_entity = onclause.parententity
prop = onclause.property
if not isinstance(onclause, attributes.QueryableAttribute):
onclause = prop
if not create_aliases:
# check for this path already present.
# don't render in that case.
edge = (left_entity, right_entity, prop.key)
if edge in self._joinpoint:
# The child's prev reference might be stale --
# it could point to a parent older than the
# current joinpoint. If this is the case,
# then we need to update it and then fix the
# tree's spine with _update_joinpoint. Copy
# and then mutate the child, which might be
# shared by a different query object.
jp = self._joinpoint[edge].copy()
jp['prev'] = (edge, self._joinpoint)
self._update_joinpoint(jp)
continue
elif onclause is not None and right_entity is None:
# TODO: no coverage here
raise NotImplementedError("query.join(a==b) not supported.")
self._join_left_to_right(
left_entity,
right_entity, onclause,
outerjoin, create_aliases, prop)
def _join_left_to_right(self, left, right,
onclause, outerjoin, create_aliases, prop):
"""append a JOIN to the query's from clause."""
self._polymorphic_adapters = self._polymorphic_adapters.copy()
if left is None:
if self._from_obj:
left = self._from_obj[0]
elif self._entities:
left = self._entities[0].entity_zero_or_selectable
if left is right and \
not create_aliases:
raise sa_exc.InvalidRequestError(
"Can't construct a join from %s to %s, they "
"are the same entity" %
(left, right))
right, right_is_aliased, onclause = self._prepare_right_side(
right, onclause,
outerjoin, create_aliases,
prop)
# if joining on a MapperProperty path,
# track the path to prevent redundant joins
if not create_aliases and prop:
self._update_joinpoint({
'_joinpoint_entity':right,
'prev':((left, right, prop.key), self._joinpoint)
})
else:
self._joinpoint = {
'_joinpoint_entity':right
}
self._join_to_left(left, right,
right_is_aliased,
onclause, outerjoin)
def _prepare_right_side(self, right, onclause, outerjoin,
create_aliases, prop):
right_mapper, right_selectable, right_is_aliased = _entity_info(right)
if right_mapper:
self._join_entities += (right, )
if right_mapper and prop and \
not right_mapper.common_parent(prop.mapper):
raise sa_exc.InvalidRequestError(
"Join target %s does not correspond to "
"the right side of join condition %s" % (right, onclause)
)
if not right_mapper and prop:
right_mapper = prop.mapper
need_adapter = False
if right_mapper and right is right_selectable:
if not right_selectable.is_derived_from(
right_mapper.mapped_table):
raise sa_exc.InvalidRequestError(
"Selectable '%s' is not derived from '%s'" %
(right_selectable.description,
right_mapper.mapped_table.description))
if not isinstance(right_selectable, expression.Alias):
right_selectable = right_selectable.alias()
right = aliased(right_mapper, right_selectable)
need_adapter = True
aliased_entity = right_mapper and \
not right_is_aliased and \
(
right_mapper.with_polymorphic or
isinstance(
right_mapper.mapped_table,
expression.Join)
)
if not need_adapter and (create_aliases or aliased_entity):
right = aliased(right)
need_adapter = True
# if an alias() of the right side was generated here,
# apply an adapter to all subsequent filter() calls
# until reset_joinpoint() is called.
if need_adapter:
self._filter_aliases = ORMAdapter(right,
equivalents=right_mapper and
right_mapper._equivalent_columns or {},
chain_to=self._filter_aliases)
# if the onclause is a ClauseElement, adapt it with any
# adapters that are in place right now
if isinstance(onclause, expression.ClauseElement):
onclause = self._adapt_clause(onclause, True, True)
# if an alias() on the right side was generated,
# which is intended to wrap a the right side in a subquery,
# ensure that columns retrieved from this target in the result
# set are also adapted.
if aliased_entity and not create_aliases:
self._mapper_loads_polymorphically_with(
right_mapper,
ORMAdapter(
right,
equivalents=right_mapper._equivalent_columns
)
)
return right, right_is_aliased, onclause
def _join_to_left(self, left, right, right_is_aliased, onclause, outerjoin):
left_mapper, left_selectable, left_is_aliased = _entity_info(left)
# this is an overly broad assumption here, but there's a
# very wide variety of situations where we rely upon orm.join's
# adaption to glue clauses together, with joined-table inheritance's
# wide array of variables taking up most of the space.
# Setting the flag here is still a guess, so it is a bug
# that we don't have definitive criterion to determine when
# adaption should be enabled (or perhaps that we're even doing the
# whole thing the way we are here).
join_to_left = not right_is_aliased and not left_is_aliased
if self._from_obj and left_selectable is not None:
replace_clause_index, clause = sql_util.find_join_source(
self._from_obj,
left_selectable)
if clause is not None:
# the entire query's FROM clause is an alias of itself (i.e.
# from_self(), similar). if the left clause is that one,
# ensure it adapts to the left side.
if self._from_obj_alias and clause is self._from_obj[0]:
join_to_left = True
# An exception case where adaption to the left edge is not
# desirable. See above note on join_to_left.
if join_to_left and isinstance(clause, expression.Join) and \
sql_util.clause_is_present(left_selectable, clause):
join_to_left = False
try:
clause = orm_join(clause,
right,
onclause, isouter=outerjoin,
join_to_left=join_to_left)
except sa_exc.ArgumentError, ae:
raise sa_exc.InvalidRequestError(
"Could not find a FROM clause to join from. "
"Tried joining to %s, but got: %s" % (right, ae))
self._from_obj = \
self._from_obj[:replace_clause_index] + \
(clause, ) + \
self._from_obj[replace_clause_index + 1:]
return
if left_mapper:
for ent in self._entities:
if ent.corresponds_to(left):
clause = ent.selectable
break
else:
clause = left
elif left_selectable is not None:
clause = left_selectable
else:
clause = None
if clause is None:
raise sa_exc.InvalidRequestError(
"Could not find a FROM clause to join from")
try:
clause = orm_join(clause, right, onclause,
isouter=outerjoin, join_to_left=join_to_left)
except sa_exc.ArgumentError, ae:
raise sa_exc.InvalidRequestError(
"Could not find a FROM clause to join from. "
"Tried joining to %s, but got: %s" % (right, ae))
self._from_obj = self._from_obj + (clause,)
def _reset_joinpoint(self):
self._joinpoint = self._joinpath
self._filter_aliases = None
@_generative(_no_statement_condition)
def reset_joinpoint(self):
"""Return a new :class:`.Query`, where the "join point" has
been reset back to the base FROM entities of the query.
This method is usually used in conjunction with the
``aliased=True`` feature of the :meth:`~.Query.join`
method. See the example in :meth:`~.Query.join` for how
this is used.
"""
self._reset_joinpoint()
@_generative(_no_clauseelement_condition)
def select_from(self, *from_obj):
"""Set the FROM clause of this :class:`.Query` explicitly.
Sending a mapped class or entity here effectively replaces the
"left edge" of any calls to :meth:`~.Query.join`, when no
joinpoint is otherwise established - usually, the default "join
point" is the leftmost entity in the :class:`~.Query` object's
list of entities to be selected.
Mapped entities or plain :class:`~.Table` or other selectables
can be sent here which will form the default FROM clause.
See the example in :meth:`~.Query.join` for a typical
usage of :meth:`~.Query.select_from`.
"""
obj = []
for fo in from_obj:
if _is_mapped_class(fo):
mapper, selectable, is_aliased_class = _entity_info(fo)
self._select_from_entity = fo
obj.append(selectable)
elif not isinstance(fo, expression.FromClause):
raise sa_exc.ArgumentError(
"select_from() accepts FromClause objects only.")
else:
obj.append(fo)
self._set_select_from(*obj)
def __getitem__(self, item):
if isinstance(item, slice):
start, stop, step = util.decode_slice(item)
if isinstance(stop, int) and \
isinstance(start, int) and \
stop - start <= 0:
return []
# perhaps we should execute a count() here so that we
# can still use LIMIT/OFFSET ?
elif (isinstance(start, int) and start < 0) \
or (isinstance(stop, int) and stop < 0):
return list(self)[item]
res = self.slice(start, stop)
if step is not None:
return list(res)[None:None:item.step]
else:
return list(res)
else:
if item == -1:
return list(self)[-1]
else:
return list(self[item:item+1])[0]
@_generative(_no_statement_condition)
def slice(self, start, stop):
"""apply LIMIT/OFFSET to the ``Query`` based on a "
"range and return the newly resulting ``Query``."""
if start is not None and stop is not None:
self._offset = (self._offset or 0) + start
self._limit = stop - start
elif start is None and stop is not None:
self._limit = stop
elif start is not None and stop is None:
self._offset = (self._offset or 0) + start
if self._offset == 0:
self._offset = None
@_generative(_no_statement_condition)
def limit(self, limit):
"""Apply a ``LIMIT`` to the query and return the newly resulting
``Query``.
"""
self._limit = limit
@_generative(_no_statement_condition)
def offset(self, offset):
"""Apply an ``OFFSET`` to the query and return the newly resulting
``Query``.
"""
self._offset = offset
@_generative(_no_statement_condition)
def distinct(self, *criterion):
"""Apply a ``DISTINCT`` to the query and return the newly resulting
``Query``.
:param \*expr: optional column expressions. When present,
the Postgresql dialect will render a ``DISTINCT ON (<expressions>>)``
construct.
"""
if not criterion:
self._distinct = True
else:
criterion = self._adapt_col_list(criterion)
if isinstance(self._distinct, list):
self._distinct += criterion
else:
self._distinct = criterion
def all(self):
"""Return the results represented by this ``Query`` as a list.
This results in an execution of the underlying query.
"""
return list(self)
@_generative(_no_clauseelement_condition)
def from_statement(self, statement):
"""Execute the given SELECT statement and return results.
This method bypasses all internal statement compilation, and the
statement is executed without modification.
The statement argument is either a string, a ``select()`` construct,
or a ``text()`` construct, and should return the set of columns
appropriate to the entity class represented by this ``Query``.
"""
if isinstance(statement, basestring):
statement = sql.text(statement)
if not isinstance(statement,
(expression._TextClause,
expression._SelectBase)):
raise sa_exc.ArgumentError(
"from_statement accepts text(), select(), "
"and union() objects only.")
self._statement = statement
def first(self):
"""Return the first result of this ``Query`` or
None if the result doesn't contain any row.
first() applies a limit of one within the generated SQL, so that
only one primary entity row is generated on the server side
(note this may consist of multiple result rows if join-loaded
collections are present).
Calling ``first()`` results in an execution of the underlying query.
"""
if self._statement is not None:
ret = list(self)[0:1]
else:
ret = list(self[0:1])
if len(ret) > 0:
return ret[0]
else:
return None
def one(self):
"""Return exactly one result or raise an exception.
Raises ``sqlalchemy.orm.exc.NoResultFound`` if the query selects
no rows. Raises ``sqlalchemy.orm.exc.MultipleResultsFound``
if multiple object identities are returned, or if multiple
rows are returned for a query that does not return object
identities.
Note that an entity query, that is, one which selects one or
more mapped classes as opposed to individual column attributes,
may ultimately represent many rows but only one row of
unique entity or entities - this is a successful result for one().
Calling ``one()`` results in an execution of the underlying query.
As of 0.6, ``one()`` fully fetches all results instead of applying
any kind of limit, so that the "unique"-ing of entities does not
conceal multiple object identities.
"""
ret = list(self)
l = len(ret)
if l == 1:
return ret[0]
elif l == 0:
raise orm_exc.NoResultFound("No row was found for one()")
else:
raise orm_exc.MultipleResultsFound(
"Multiple rows were found for one()")
def scalar(self):
"""Return the first element of the first result or None
if no rows present. If multiple rows are returned,
raises MultipleResultsFound.
>>> session.query(Item).scalar()
<Item>
>>> session.query(Item.id).scalar()
1
>>> session.query(Item.id).filter(Item.id < 0).scalar()
None
>>> session.query(Item.id, Item.name).scalar()
1
>>> session.query(func.count(Parent.id)).scalar()
20
This results in an execution of the underlying query.
"""
try:
ret = self.one()
if not isinstance(ret, tuple):
return ret
return ret[0]
except orm_exc.NoResultFound:
return None
def __iter__(self):
context = self._compile_context()
context.statement.use_labels = True
if self._autoflush and not self._populate_existing:
self.session._autoflush()
return self._execute_and_instances(context)
def _connection_from_session(self, **kw):
conn = self.session.connection(
**kw)
if self._execution_options:
conn = conn.execution_options(**self._execution_options)
return conn
def _execute_and_instances(self, querycontext):
conn = self._connection_from_session(
mapper = self._mapper_zero_or_none(),
clause = querycontext.statement,
close_with_result=True)
result = conn.execute(querycontext.statement, self._params)
return self.instances(result, querycontext)
@property
def column_descriptions(self):
"""Return metadata about the columns which would be
returned by this :class:`.Query`.
Format is a list of dictionaries::
user_alias = aliased(User, name='user2')
q = sess.query(User, User.id, user_alias)
# this expression:
q.column_descriptions
# would return:
[
{
'name':'User',
'type':User,
'aliased':False,
'expr':User,
},
{
'name':'id',
'type':Integer(),
'aliased':False,
'expr':User.id,
},
{
'name':'user2',
'type':User,
'aliased':True,
'expr':user_alias
}
]
"""
return [
{
'name':ent._label_name,
'type':ent.type,
'aliased':getattr(ent, 'is_aliased_class', False),
'expr':ent.expr
}
for ent in self._entities
]
def instances(self, cursor, __context=None):
"""Given a ResultProxy cursor as returned by connection.execute(),
return an ORM result as an iterator.
e.g.::
result = engine.execute("select * from users")
for u in session.query(User).instances(result):
print u
"""
session = self.session
context = __context
if context is None:
context = QueryContext(self)
context.runid = _new_runid()
filter_fns = [ent.filter_fn
for ent in self._entities]
filtered = id in filter_fns
single_entity = filtered and len(self._entities) == 1
if filtered:
if single_entity:
filter_fn = id
else:
def filter_fn(row):
return tuple(fn(x) for x, fn in zip(row, filter_fns))
custom_rows = single_entity and \
self._entities[0].mapper.dispatch.append_result
(process, labels) = \
zip(*[
query_entity.row_processor(self, context, custom_rows)
for query_entity in self._entities
])
while True:
context.progress = {}
context.partials = {}
if self._yield_per:
fetch = cursor.fetchmany(self._yield_per)
if not fetch:
break
else:
fetch = cursor.fetchall()
if custom_rows:
rows = []
for row in fetch:
process[0](row, rows)
elif single_entity:
rows = [process[0](row, None) for row in fetch]
else:
rows = [util.NamedTuple([proc(row, None) for proc in process],
labels) for row in fetch]
if filtered:
rows = util.unique_list(rows, filter_fn)
if context.refresh_state and self._only_load_props \
and context.refresh_state in context.progress:
context.refresh_state.commit(
context.refresh_state.dict, self._only_load_props)
context.progress.pop(context.refresh_state)
session._finalize_loaded(context.progress)
for ii, (dict_, attrs) in context.partials.iteritems():
ii.commit(dict_, attrs)
for row in rows:
yield row
if not self._yield_per:
break
def merge_result(self, iterator, load=True):
"""Merge a result into this :class:`.Query` object's Session.
Given an iterator returned by a :class:`.Query` of the same structure as this
one, return an identical iterator of results, with all mapped
instances merged into the session using :meth:`.Session.merge`. This is an
optimized method which will merge all mapped instances, preserving the
structure of the result rows and unmapped columns with less method
overhead than that of calling :meth:`.Session.merge` explicitly for each
value.
The structure of the results is determined based on the column list of
this :class:`.Query` - if these do not correspond, unchecked errors will occur.
The 'load' argument is the same as that of :meth:`.Session.merge`.
For an example of how :meth:`~.Query.merge_result` is used, see
the source code for the example :ref:`examples_caching`, where
:meth:`~.Query.merge_result` is used to efficiently restore state
from a cache back into a target :class:`.Session`.
"""
session = self.session
if load:
# flush current contents if we expect to load data
session._autoflush()
autoflush = session.autoflush
try:
session.autoflush = False
single_entity = len(self._entities) == 1
if single_entity:
if isinstance(self._entities[0], _MapperEntity):
result = [session._merge(
attributes.instance_state(instance),
attributes.instance_dict(instance),
load=load, _recursive={})
for instance in iterator]
else:
result = list(iterator)
else:
mapped_entities = [i for i, e in enumerate(self._entities)
if isinstance(e, _MapperEntity)]
result = []
for row in iterator:
newrow = list(row)
for i in mapped_entities:
newrow[i] = session._merge(
attributes.instance_state(newrow[i]),
attributes.instance_dict(newrow[i]),
load=load, _recursive={})
result.append(util.NamedTuple(newrow, row._labels))
return iter(result)
finally:
session.autoflush = autoflush
@classmethod
def _get_from_identity(cls, session, key, passive):
"""Look up the given key in the given session's identity map,
check the object for expired state if found.
"""
instance = session.identity_map.get(key)
if instance is not None:
state = attributes.instance_state(instance)
# expired - ensure it still exists
if state.expired:
if passive is attributes.PASSIVE_NO_FETCH:
# TODO: no coverage here
return attributes.PASSIVE_NO_RESULT
elif passive is attributes.PASSIVE_NO_FETCH_RELATED:
# this mode is used within a flush and the instance's
# expired state will be checked soon enough, if necessary
return instance
try:
state(passive)
except orm_exc.ObjectDeletedError:
session._remove_newly_deleted(state)
return None
return instance
else:
return None
def _load_on_ident(self, key, refresh_state=None, lockmode=None,
only_load_props=None):
"""Load the given identity key from the database."""
lockmode = lockmode or self._lockmode
if key is not None:
ident = key[1]
else:
ident = None
if refresh_state is None:
q = self._clone()
q._get_condition()
else:
q = self._clone()
if ident is not None:
mapper = self._mapper_zero()
(_get_clause, _get_params) = mapper._get_clause
# None present in ident - turn those comparisons
# into "IS NULL"
if None in ident:
nones = set([
_get_params[col].key for col, value in
zip(mapper.primary_key, ident) if value is None
])
_get_clause = sql_util.adapt_criterion_to_null(
_get_clause, nones)
_get_clause = q._adapt_clause(_get_clause, True, False)
q._criterion = _get_clause
params = dict([
(_get_params[primary_key].key, id_val)
for id_val, primary_key in zip(ident, mapper.primary_key)
])
q._params = params
if lockmode is not None:
q._lockmode = lockmode
q._get_options(
populate_existing=bool(refresh_state),
version_check=(lockmode is not None),
only_load_props=only_load_props,
refresh_state=refresh_state)
q._order_by = None
try:
return q.one()
except orm_exc.NoResultFound:
return None
@property
def _select_args(self):
return {
'limit':self._limit,
'offset':self._offset,
'distinct':self._distinct,
'group_by':self._group_by or None,
'having':self._having
}
@property
def _should_nest_selectable(self):
kwargs = self._select_args
return (kwargs.get('limit') is not None or
kwargs.get('offset') is not None or
kwargs.get('distinct', False))
def count(self):
"""Return a count of rows this Query would return.
This generates the SQL for this Query as follows::
SELECT count(1) AS count_1 FROM (
SELECT <rest of query follows...>
) AS anon_1
Note the above scheme is newly refined in 0.7
(as of 0.7b3).
For fine grained control over specific columns
to count, to skip the usage of a subquery or
otherwise control of the FROM clause,
or to use other aggregate functions,
use :attr:`~sqlalchemy.sql.expression.func` expressions in conjunction
with :meth:`~.Session.query`, i.e.::
from sqlalchemy import func
# count User records, without
# using a subquery.
session.query(func.count(User.id))
# return count of user "id" grouped
# by "name"
session.query(func.count(User.id)).\\
group_by(User.name)
from sqlalchemy import distinct
# count distinct "name" values
session.query(func.count(distinct(User.name)))
"""
col = sql.func.count(sql.literal_column('*'))
return self.from_self(col).scalar()
def delete(self, synchronize_session='evaluate'):
"""Perform a bulk delete query.
Deletes rows matched by this query from the database.
:param synchronize_session: chooses the strategy for the removal of
matched objects from the session. Valid values are:
``False`` - don't synchronize the session. This option is the most
efficient and is reliable once the session is expired, which
typically occurs after a commit(), or explicitly using
expire_all(). Before the expiration, objects may still remain in
the session which were in fact deleted which can lead to confusing
results if they are accessed via get() or already loaded
collections.
``'fetch'`` - performs a select query before the delete to find
objects that are matched by the delete query and need to be
removed from the session. Matched objects are removed from the
session.
``'evaluate'`` - Evaluate the query's criteria in Python straight on
the objects in the session. If evaluation of the criteria isn't
implemented, an error is raised. In that case you probably
want to use the 'fetch' strategy as a fallback.
The expression evaluator currently doesn't account for differing
string collations between the database and Python.
Returns the number of rows deleted, excluding any cascades.
The method does *not* offer in-Python cascading of relationships - it
is assumed that ON DELETE CASCADE is configured for any foreign key
references which require it. The Session needs to be expired (occurs
automatically after commit(), or call expire_all()) in order for the
state of dependent objects subject to delete or delete-orphan cascade
to be correctly represented.
Note that the :meth:`.MapperEvents.before_delete` and
:meth:`.MapperEvents.after_delete`
events are **not** invoked from this method. It instead
invokes :meth:`.SessionEvents.after_bulk_delete`.
"""
#TODO: lots of duplication and ifs - probably needs to be
# refactored to strategies
#TODO: cascades need handling.
if synchronize_session not in [False, 'evaluate', 'fetch']:
raise sa_exc.ArgumentError(
"Valid strategies for session "
"synchronization are False, 'evaluate' and "
"'fetch'")
self._no_select_modifiers("delete")
self = self.enable_eagerloads(False)
context = self._compile_context()
if len(context.statement.froms) != 1 or \
not isinstance(context.statement.froms[0], schema.Table):
raise sa_exc.ArgumentError("Only deletion via a single table "
"query is currently supported")
primary_table = context.statement.froms[0]
session = self.session
if self._autoflush:
session._autoflush()
if synchronize_session == 'evaluate':
try:
evaluator_compiler = evaluator.EvaluatorCompiler()
if self.whereclause is not None:
eval_condition = evaluator_compiler.process(
self.whereclause)
else:
def eval_condition(obj):
return True
except evaluator.UnevaluatableError:
raise sa_exc.InvalidRequestError(
"Could not evaluate current criteria in Python. "
"Specify 'fetch' or False for the synchronize_session "
"parameter.")
target_cls = self._mapper_zero().class_
#TODO: detect when the where clause is a trivial primary key match
objs_to_expunge = [
obj for (cls, pk),obj in
session.identity_map.iteritems()
if issubclass(cls, target_cls) and
eval_condition(obj)]
elif synchronize_session == 'fetch':
#TODO: use RETURNING when available
select_stmt = context.statement.with_only_columns(
primary_table.primary_key)
matched_rows = session.execute(
select_stmt,
params=self._params).fetchall()
delete_stmt = sql.delete(primary_table, context.whereclause)
result = session.execute(delete_stmt, params=self._params)
if synchronize_session == 'evaluate':
for obj in objs_to_expunge:
session._remove_newly_deleted(attributes.instance_state(obj))
elif synchronize_session == 'fetch':
target_mapper = self._mapper_zero()
for primary_key in matched_rows:
identity_key = target_mapper.identity_key_from_primary_key(
list(primary_key))
if identity_key in session.identity_map:
session._remove_newly_deleted(
attributes.instance_state(
session.identity_map[identity_key]
)
)
session.dispatch.after_bulk_delete(session, self, context, result)
return result.rowcount
def update(self, values, synchronize_session='evaluate'):
"""Perform a bulk update query.
Updates rows matched by this query in the database.
:param values: a dictionary with attributes names as keys and literal
values or sql expressions as values.
:param synchronize_session: chooses the strategy to update the
attributes on objects in the session. Valid values are:
``False`` - don't synchronize the session. This option is the most
efficient and is reliable once the session is expired, which
typically occurs after a commit(), or explicitly using
expire_all(). Before the expiration, updated objects may still
remain in the session with stale values on their attributes, which
can lead to confusing results.
``'fetch'`` - performs a select query before the update to find
objects that are matched by the update query. The updated
attributes are expired on matched objects.
``'evaluate'`` - Evaluate the Query's criteria in Python straight on
the objects in the session. If evaluation of the criteria isn't
implemented, an exception is raised.
The expression evaluator currently doesn't account for differing
string collations between the database and Python.
Returns the number of rows matched by the update.
The method does *not* offer in-Python cascading of relationships - it
is assumed that ON UPDATE CASCADE is configured for any foreign key
references which require it.
The Session needs to be expired (occurs automatically after commit(),
or call expire_all()) in order for the state of dependent objects
subject foreign key cascade to be correctly represented.
Note that the :meth:`.MapperEvents.before_update` and
:meth:`.MapperEvents.after_update`
events are **not** invoked from this method. It instead
invokes :meth:`.SessionEvents.after_bulk_update`.
"""
#TODO: value keys need to be mapped to corresponding sql cols and
# instr.attr.s to string keys
#TODO: updates of manytoone relationships need to be converted to
# fk assignments
#TODO: cascades need handling.
if synchronize_session == 'expire':
util.warn_deprecated("The 'expire' value as applied to "
"the synchronize_session argument of "
"query.update() is now called 'fetch'")
synchronize_session = 'fetch'
if synchronize_session not in [False, 'evaluate', 'fetch']:
raise sa_exc.ArgumentError(
"Valid strategies for session synchronization "
"are False, 'evaluate' and 'fetch'")
self._no_select_modifiers("update")
self = self.enable_eagerloads(False)
context = self._compile_context()
if len(context.statement.froms) != 1 or \
not isinstance(context.statement.froms[0], schema.Table):
raise sa_exc.ArgumentError(
"Only update via a single table query is "
"currently supported")
primary_table = context.statement.froms[0]
session = self.session
if self._autoflush:
session._autoflush()
if synchronize_session == 'evaluate':
try:
evaluator_compiler = evaluator.EvaluatorCompiler()
if self.whereclause is not None:
eval_condition = evaluator_compiler.process(
self.whereclause)
else:
def eval_condition(obj):
return True
value_evaluators = {}
for key,value in values.iteritems():
key = _attr_as_key(key)
value_evaluators[key] = evaluator_compiler.process(
expression._literal_as_binds(value))
except evaluator.UnevaluatableError:
raise sa_exc.InvalidRequestError(
"Could not evaluate current criteria in Python. "
"Specify 'fetch' or False for the "
"synchronize_session parameter.")
target_cls = self._mapper_zero().class_
matched_objects = []
for (cls, pk),obj in session.identity_map.iteritems():
evaluated_keys = value_evaluators.keys()
if issubclass(cls, target_cls) and eval_condition(obj):
matched_objects.append(obj)
elif synchronize_session == 'fetch':
select_stmt = context.statement.with_only_columns(
primary_table.primary_key)
matched_rows = session.execute(
select_stmt,
params=self._params).fetchall()
update_stmt = sql.update(primary_table, context.whereclause, values)
result = session.execute(update_stmt, params=self._params)
if synchronize_session == 'evaluate':
target_cls = self._mapper_zero().class_
for obj in matched_objects:
state, dict_ = attributes.instance_state(obj),\
attributes.instance_dict(obj)
# only evaluate unmodified attributes
to_evaluate = state.unmodified.intersection(
evaluated_keys)
for key in to_evaluate:
dict_[key] = value_evaluators[key](obj)
state.commit(dict_, list(to_evaluate))
# expire attributes with pending changes
# (there was no autoflush, so they are overwritten)
state.expire_attributes(dict_,
set(evaluated_keys).
difference(to_evaluate))
elif synchronize_session == 'fetch':
target_mapper = self._mapper_zero()
for primary_key in matched_rows:
identity_key = target_mapper.identity_key_from_primary_key(
list(primary_key))
if identity_key in session.identity_map:
session.expire(
session.identity_map[identity_key],
[_attr_as_key(k) for k in values]
)
session.dispatch.after_bulk_update(session, self, context, result)
return result.rowcount
def _compile_context(self, labels=True):
context = QueryContext(self)
if context.statement is not None:
return context
if self._lockmode:
try:
for_update = {'read': 'read',
'update': True,
'update_nowait': 'nowait',
None: False}[self._lockmode]
except KeyError:
raise sa_exc.ArgumentError(
"Unknown lockmode %r" % self._lockmode)
else:
for_update = False
for entity in self._entities:
entity.setup_context(self, context)
for rec in context.create_eager_joins:
strategy = rec[0]
strategy(*rec[1:])
eager_joins = context.eager_joins.values()
if context.from_clause:
# "load from explicit FROMs" mode,
# i.e. when select_from() or join() is used
froms = list(context.from_clause)
else:
# "load from discrete FROMs" mode,
# i.e. when each _MappedEntity has its own FROM
froms = context.froms
if self._enable_single_crit:
self._adjust_for_single_inheritance(context)
if not context.primary_columns:
if self._only_load_props:
raise sa_exc.InvalidRequestError(
"No column-based properties specified for "
"refresh operation. Use session.expire() "
"to reload collections and related items.")
else:
raise sa_exc.InvalidRequestError(
"Query contains no columns with which to "
"SELECT from.")
if context.multi_row_eager_loaders and self._should_nest_selectable:
# for eager joins present and LIMIT/OFFSET/DISTINCT,
# wrap the query inside a select,
# then append eager joins onto that
if context.order_by:
order_by_col_expr = list(
chain(*[
sql_util.unwrap_order_by(o)
for o in context.order_by
])
)
else:
context.order_by = None
order_by_col_expr = []
inner = sql.select(
context.primary_columns + order_by_col_expr,
context.whereclause,
from_obj=froms,
use_labels=labels,
correlate=False,
# TODO: this order_by is only needed if
# LIMIT/OFFSET is present in self._select_args,
# else the application on the outside is enough
order_by=context.order_by,
**self._select_args
)
for hint in self._with_hints:
inner = inner.with_hint(*hint)
if self._correlate:
inner = inner.correlate(*self._correlate)
inner = inner.alias()
equivs = self.__all_equivs()
context.adapter = sql_util.ColumnAdapter(inner, equivs)
statement = sql.select(
[inner] + context.secondary_columns,
for_update=for_update,
use_labels=labels)
from_clause = inner
for eager_join in eager_joins:
# EagerLoader places a 'stop_on' attribute on the join,
# giving us a marker as to where the "splice point" of
# the join should be
from_clause = sql_util.splice_joins(
from_clause,
eager_join, eager_join.stop_on)
statement.append_from(from_clause)
if context.order_by:
statement.append_order_by(
*context.adapter.copy_and_process(
context.order_by
)
)
statement.append_order_by(*context.eager_order_by)
else:
if not context.order_by:
context.order_by = None
if self._distinct and context.order_by:
order_by_col_expr = list(
chain(*[
sql_util.unwrap_order_by(o)
for o in context.order_by
])
)
context.primary_columns += order_by_col_expr
froms += tuple(context.eager_joins.values())
statement = sql.select(
context.primary_columns +
context.secondary_columns,
context.whereclause,
from_obj=froms,
use_labels=labels,
for_update=for_update,
correlate=False,
order_by=context.order_by,
**self._select_args
)
for hint in self._with_hints:
statement = statement.with_hint(*hint)
if self._correlate:
statement = statement.correlate(*self._correlate)
if context.eager_order_by:
statement.append_order_by(*context.eager_order_by)
context.statement = statement
return context
def _adjust_for_single_inheritance(self, context):
"""Apply single-table-inheritance filtering.
For all distinct single-table-inheritance mappers represented in the
columns clause of this query, add criterion to the WHERE clause of the
given QueryContext such that only the appropriate subtypes are
selected from the total results.
"""
for entity, (mapper, adapter, s, i, w) in \
self._mapper_adapter_map.iteritems():
if entity in self._join_entities:
continue
single_crit = mapper._single_table_criterion
if single_crit is not None:
if adapter:
single_crit = adapter.traverse(single_crit)
single_crit = self._adapt_clause(single_crit, False, False)
context.whereclause = sql.and_(
context.whereclause, single_crit)
def __str__(self):
return str(self._compile_context().statement)
class _QueryEntity(object):
"""represent an entity column returned within a Query result."""
def __new__(cls, *args, **kwargs):
if cls is _QueryEntity:
entity = args[1]
if not isinstance(entity, basestring) and \
_is_mapped_class(entity):
cls = _MapperEntity
else:
cls = _ColumnEntity
return object.__new__(cls)
def _clone(self):
q = self.__class__.__new__(self.__class__)
q.__dict__ = self.__dict__.copy()
return q
class _MapperEntity(_QueryEntity):
"""mapper/class/AliasedClass entity"""
def __init__(self, query, entity):
self.primary_entity = not query._entities
query._entities.append(self)
self.entities = [entity]
self.entity_zero = self.expr = entity
def setup_entity(self, entity, mapper, adapter,
from_obj, is_aliased_class, with_polymorphic):
self.mapper = mapper
self.adapter = adapter
self.selectable = from_obj
self._with_polymorphic = with_polymorphic
self._polymorphic_discriminator = None
self.is_aliased_class = is_aliased_class
if is_aliased_class:
self.path_entity = self.entity_zero = entity
self._path = (entity,)
self._label_name = self.entity_zero._sa_label_name
self._reduced_path = (self.path_entity, )
else:
self.path_entity = mapper
self._path = (mapper,)
self._reduced_path = (mapper.base_mapper, )
self.entity_zero = mapper
self._label_name = self.mapper.class_.__name__
def set_with_polymorphic(self, query, cls_or_mappers,
selectable, discriminator):
if cls_or_mappers is None:
query._reset_polymorphic_adapter(self.mapper)
return
mappers, from_obj = self.mapper._with_polymorphic_args(
cls_or_mappers, selectable)
self._with_polymorphic = mappers
self._polymorphic_discriminator = discriminator
# TODO: do the wrapped thing here too so that
# with_polymorphic() can be applied to aliases
if not self.is_aliased_class:
self.selectable = from_obj
query._mapper_loads_polymorphically_with(self.mapper,
sql_util.ColumnAdapter(from_obj,
self.mapper._equivalent_columns))
filter_fn = id
@property
def type(self):
return self.mapper.class_
@property
def entity_zero_or_selectable(self):
return self.entity_zero
def corresponds_to(self, entity):
if _is_aliased_class(entity) or self.is_aliased_class:
return entity is self.path_entity
else:
return entity.common_parent(self.path_entity)
def adapt_to_selectable(self, query, sel):
query._entities.append(self)
def _get_entity_clauses(self, query, context):
adapter = None
if not self.is_aliased_class and query._polymorphic_adapters:
adapter = query._polymorphic_adapters.get(self.mapper, None)
if not adapter and self.adapter:
adapter = self.adapter
if adapter:
if query._from_obj_alias:
ret = adapter.wrap(query._from_obj_alias)
else:
ret = adapter
else:
ret = query._from_obj_alias
return ret
def row_processor(self, query, context, custom_rows):
adapter = self._get_entity_clauses(query, context)
if context.adapter and adapter:
adapter = adapter.wrap(context.adapter)
elif not adapter:
adapter = context.adapter
# polymorphic mappers which have concrete tables in
# their hierarchy usually
# require row aliasing unconditionally.
if not adapter and self.mapper._requires_row_aliasing:
adapter = sql_util.ColumnAdapter(
self.selectable,
self.mapper._equivalent_columns)
if self.primary_entity:
_instance = self.mapper._instance_processor(
context,
self._path,
self._reduced_path,
adapter,
only_load_props=query._only_load_props,
refresh_state=context.refresh_state,
polymorphic_discriminator=
self._polymorphic_discriminator
)
else:
_instance = self.mapper._instance_processor(
context,
self._path,
self._reduced_path,
adapter,
polymorphic_discriminator=
self._polymorphic_discriminator)
return _instance, self._label_name
def setup_context(self, query, context):
adapter = self._get_entity_clauses(query, context)
context.froms += (self.selectable,)
if context.order_by is False and self.mapper.order_by:
context.order_by = self.mapper.order_by
# apply adaptation to the mapper's order_by if needed.
if adapter:
context.order_by = adapter.adapt_list(
util.to_list(
context.order_by
)
)
if self._with_polymorphic:
poly_properties = self.mapper._iterate_polymorphic_properties(
self._with_polymorphic)
else:
poly_properties = self.mapper._polymorphic_properties
for value in poly_properties:
if query._only_load_props and \
value.key not in query._only_load_props:
continue
value.setup(
context,
self,
self._path,
self._reduced_path,
adapter,
only_load_props=query._only_load_props,
column_collection=context.primary_columns
)
if self._polymorphic_discriminator is not None:
if adapter:
pd = adapter.columns[self._polymorphic_discriminator]
else:
pd = self._polymorphic_discriminator
context.primary_columns.append(pd)
def __str__(self):
return str(self.mapper)
class _ColumnEntity(_QueryEntity):
"""Column/expression based entity."""
def __init__(self, query, column, namespace=None):
self.expr = column
self.namespace = namespace
if isinstance(column, basestring):
column = sql.literal_column(column)
self._label_name = column.name
elif isinstance(column, (
attributes.QueryableAttribute,
interfaces.PropComparator
)):
self._label_name = column.key
column = column.__clause_element__()
else:
self._label_name = getattr(column, 'key', None)
if not isinstance(column, expression.ColumnElement) and \
hasattr(column, '_select_iterable'):
for c in column._select_iterable:
if c is column:
break
_ColumnEntity(query, c, namespace=column)
if c is not column:
return
if not isinstance(column, sql.ColumnElement):
raise sa_exc.InvalidRequestError(
"SQL expression, column, or mapped entity "
"expected - got '%r'" % (column, )
)
# If the Column is unnamed, give it a
# label() so that mutable column expressions
# can be located in the result even
# if the expression's identity has been changed
# due to adaption.
if not column._label:
column = column.label(None)
query._entities.append(self)
self.column = column
self.froms = set()
# look for ORM entities represented within the
# given expression. Try to count only entities
# for columns whose FROM object is in the actual list
# of FROMs for the overall expression - this helps
# subqueries which were built from ORM constructs from
# leaking out their entities into the main select construct
self.actual_froms = actual_froms = set(column._from_objects)
self.entities = util.OrderedSet(
elem._annotations['parententity']
for elem in visitors.iterate(column, {})
if 'parententity' in elem._annotations
and actual_froms.intersection(elem._from_objects)
)
if self.entities:
self.entity_zero = list(self.entities)[0]
elif self.namespace is not None:
self.entity_zero = self.namespace
else:
self.entity_zero = None
@property
def entity_zero_or_selectable(self):
if self.entity_zero is not None:
return self.entity_zero
elif self.actual_froms:
return list(self.actual_froms)[0]
else:
return None
@property
def type(self):
return self.column.type
def filter_fn(self, item):
return item
def adapt_to_selectable(self, query, sel):
c = _ColumnEntity(query, sel.corresponding_column(self.column))
c._label_name = self._label_name
c.entity_zero = self.entity_zero
c.entities = self.entities
def setup_entity(self, entity, mapper, adapter, from_obj,
is_aliased_class, with_polymorphic):
if 'selectable' not in self.__dict__:
self.selectable = from_obj
self.froms.add(from_obj)
def corresponds_to(self, entity):
if self.entity_zero is None:
return False
elif _is_aliased_class(entity):
return entity is self.entity_zero
else:
return not _is_aliased_class(self.entity_zero) and \
entity.common_parent(self.entity_zero)
def _resolve_expr_against_query_aliases(self, query, expr, context):
return query._adapt_clause(expr, False, True)
def row_processor(self, query, context, custom_rows):
column = self._resolve_expr_against_query_aliases(
query, self.column, context)
if context.adapter:
column = context.adapter.columns[column]
def proc(row, result):
return row[column]
return proc, self._label_name
def setup_context(self, query, context):
column = self._resolve_expr_against_query_aliases(
query, self.column, context)
context.froms += tuple(self.froms)
context.primary_columns.append(column)
def __str__(self):
return str(self.column)
log.class_logger(Query)
class QueryContext(object):
multi_row_eager_loaders = False
adapter = None
froms = ()
def __init__(self, query):
if query._statement is not None:
if isinstance(query._statement, expression._SelectBase) and \
not query._statement.use_labels:
self.statement = query._statement.apply_labels()
else:
self.statement = query._statement
else:
self.statement = None
self.from_clause = query._from_obj
self.whereclause = query._criterion
self.order_by = query._order_by
self.query = query
self.session = query.session
self.populate_existing = query._populate_existing
self.invoke_all_eagers = query._invoke_all_eagers
self.version_check = query._version_check
self.refresh_state = query._refresh_state
self.primary_columns = []
self.secondary_columns = []
self.eager_order_by = []
self.eager_joins = {}
self.create_eager_joins = []
self.propagate_options = set(o for o in query._with_options if
o.propagate_to_loaders)
self.attributes = query._attributes.copy()
class AliasOption(interfaces.MapperOption):
def __init__(self, alias):
self.alias = alias
def process_query(self, query):
if isinstance(self.alias, basestring):
alias = query._mapper_zero().mapped_table.alias(self.alias)
else:
alias = self.alias
query._from_obj_alias = sql_util.ColumnAdapter(alias)
_new_runid = util.counter()