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CouchPotatoServer/libs/sqlalchemy/engine/base.py

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# engine/base.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
"""Basic components for SQL execution and interfacing with DB-API.
Defines the basic components used to interface DB-API modules with
higher-level statement-construction, connection-management, execution
and result contexts.
"""
__all__ = [
'BufferedColumnResultProxy', 'BufferedColumnRow',
'BufferedRowResultProxy','Compiled', 'Connectable', 'Connection',
'Dialect', 'Engine','ExecutionContext', 'NestedTransaction',
'ResultProxy', 'RootTransaction','RowProxy', 'SchemaIterator',
'StringIO', 'Transaction', 'TwoPhaseTransaction',
'connection_memoize']
import inspect, StringIO, sys, operator
from itertools import izip
from sqlalchemy import exc, schema, util, types, log, interfaces, \
event, events
from sqlalchemy.sql import expression, util as sql_util
from sqlalchemy import processors
import collections
class Dialect(object):
"""Define the behavior of a specific database and DB-API combination.
Any aspect of metadata definition, SQL query generation,
execution, result-set handling, or anything else which varies
between databases is defined under the general category of the
Dialect. The Dialect acts as a factory for other
database-specific object implementations including
ExecutionContext, Compiled, DefaultGenerator, and TypeEngine.
All Dialects implement the following attributes:
name
identifying name for the dialect from a DBAPI-neutral point of view
(i.e. 'sqlite')
driver
identifying name for the dialect's DBAPI
positional
True if the paramstyle for this Dialect is positional.
paramstyle
the paramstyle to be used (some DB-APIs support multiple
paramstyles).
convert_unicode
True if Unicode conversion should be applied to all ``str``
types.
encoding
type of encoding to use for unicode, usually defaults to
'utf-8'.
statement_compiler
a :class:`~Compiled` class used to compile SQL statements
ddl_compiler
a :class:`~Compiled` class used to compile DDL statements
server_version_info
a tuple containing a version number for the DB backend in use.
This value is only available for supporting dialects, and is
typically populated during the initial connection to the database.
default_schema_name
the name of the default schema. This value is only available for
supporting dialects, and is typically populated during the
initial connection to the database.
execution_ctx_cls
a :class:`.ExecutionContext` class used to handle statement execution
execute_sequence_format
either the 'tuple' or 'list' type, depending on what cursor.execute()
accepts for the second argument (they vary).
preparer
a :class:`~sqlalchemy.sql.compiler.IdentifierPreparer` class used to
quote identifiers.
supports_alter
``True`` if the database supports ``ALTER TABLE``.
max_identifier_length
The maximum length of identifier names.
supports_unicode_statements
Indicate whether the DB-API can receive SQL statements as Python
unicode strings
supports_unicode_binds
Indicate whether the DB-API can receive string bind parameters
as Python unicode strings
supports_sane_rowcount
Indicate whether the dialect properly implements rowcount for
``UPDATE`` and ``DELETE`` statements.
supports_sane_multi_rowcount
Indicate whether the dialect properly implements rowcount for
``UPDATE`` and ``DELETE`` statements when executed via
executemany.
preexecute_autoincrement_sequences
True if 'implicit' primary key functions must be executed separately
in order to get their value. This is currently oriented towards
Postgresql.
implicit_returning
use RETURNING or equivalent during INSERT execution in order to load
newly generated primary keys and other column defaults in one execution,
which are then available via inserted_primary_key.
If an insert statement has returning() specified explicitly,
the "implicit" functionality is not used and inserted_primary_key
will not be available.
dbapi_type_map
A mapping of DB-API type objects present in this Dialect's
DB-API implementation mapped to TypeEngine implementations used
by the dialect.
This is used to apply types to result sets based on the DB-API
types present in cursor.description; it only takes effect for
result sets against textual statements where no explicit
typemap was present.
colspecs
A dictionary of TypeEngine classes from sqlalchemy.types mapped
to subclasses that are specific to the dialect class. This
dictionary is class-level only and is not accessed from the
dialect instance itself.
supports_default_values
Indicates if the construct ``INSERT INTO tablename DEFAULT
VALUES`` is supported
supports_sequences
Indicates if the dialect supports CREATE SEQUENCE or similar.
sequences_optional
If True, indicates if the "optional" flag on the Sequence() construct
should signal to not generate a CREATE SEQUENCE. Applies only to
dialects that support sequences. Currently used only to allow Postgresql
SERIAL to be used on a column that specifies Sequence() for usage on
other backends.
supports_native_enum
Indicates if the dialect supports a native ENUM construct.
This will prevent types.Enum from generating a CHECK
constraint when that type is used.
supports_native_boolean
Indicates if the dialect supports a native boolean construct.
This will prevent types.Boolean from generating a CHECK
constraint when that type is used.
"""
def create_connect_args(self, url):
"""Build DB-API compatible connection arguments.
Given a :class:`~sqlalchemy.engine.url.URL` object, returns a tuple
consisting of a `*args`/`**kwargs` suitable to send directly
to the dbapi's connect function.
"""
raise NotImplementedError()
@classmethod
def type_descriptor(cls, typeobj):
"""Transform a generic type to a dialect-specific type.
Dialect classes will usually use the
:func:`~sqlalchemy.types.adapt_type` function in the types module to
make this job easy.
The returned result is cached *per dialect class* so can
contain no dialect-instance state.
"""
raise NotImplementedError()
def initialize(self, connection):
"""Called during strategized creation of the dialect with a
connection.
Allows dialects to configure options based on server version info or
other properties.
The connection passed here is a SQLAlchemy Connection object,
with full capabilities.
The initalize() method of the base dialect should be called via
super().
"""
pass
def reflecttable(self, connection, table, include_columns=None):
"""Load table description from the database.
Given a :class:`.Connection` and a
:class:`~sqlalchemy.schema.Table` object, reflect its columns and
properties from the database. If include_columns (a list or
set) is specified, limit the autoload to the given column
names.
The default implementation uses the
:class:`~sqlalchemy.engine.reflection.Inspector` interface to
provide the output, building upon the granular table/column/
constraint etc. methods of :class:`.Dialect`.
"""
raise NotImplementedError()
def get_columns(self, connection, table_name, schema=None, **kw):
"""Return information about columns in `table_name`.
Given a :class:`.Connection`, a string
`table_name`, and an optional string `schema`, return column
information as a list of dictionaries with these keys:
name
the column's name
type
[sqlalchemy.types#TypeEngine]
nullable
boolean
default
the column's default value
autoincrement
boolean
sequence
a dictionary of the form
{'name' : str, 'start' :int, 'increment': int}
Additional column attributes may be present.
"""
raise NotImplementedError()
def get_primary_keys(self, connection, table_name, schema=None, **kw):
"""Return information about primary keys in `table_name`.
Given a :class:`.Connection`, a string
`table_name`, and an optional string `schema`, return primary
key information as a list of column names.
"""
raise NotImplementedError()
def get_pk_constraint(self, table_name, schema=None, **kw):
"""Return information about the primary key constraint on
table_name`.
Given a string `table_name`, and an optional string `schema`, return
primary key information as a dictionary with these keys:
constrained_columns
a list of column names that make up the primary key
name
optional name of the primary key constraint.
"""
raise NotImplementedError()
def get_foreign_keys(self, connection, table_name, schema=None, **kw):
"""Return information about foreign_keys in `table_name`.
Given a :class:`.Connection`, a string
`table_name`, and an optional string `schema`, return foreign
key information as a list of dicts with these keys:
name
the constraint's name
constrained_columns
a list of column names that make up the foreign key
referred_schema
the name of the referred schema
referred_table
the name of the referred table
referred_columns
a list of column names in the referred table that correspond to
constrained_columns
"""
raise NotImplementedError()
def get_table_names(self, connection, schema=None, **kw):
"""Return a list of table names for `schema`."""
raise NotImplementedError
def get_view_names(self, connection, schema=None, **kw):
"""Return a list of all view names available in the database.
schema:
Optional, retrieve names from a non-default schema.
"""
raise NotImplementedError()
def get_view_definition(self, connection, view_name, schema=None, **kw):
"""Return view definition.
Given a :class:`.Connection`, a string
`view_name`, and an optional string `schema`, return the view
definition.
"""
raise NotImplementedError()
def get_indexes(self, connection, table_name, schema=None, **kw):
"""Return information about indexes in `table_name`.
Given a :class:`.Connection`, a string
`table_name` and an optional string `schema`, return index
information as a list of dictionaries with these keys:
name
the index's name
column_names
list of column names in order
unique
boolean
"""
raise NotImplementedError()
def normalize_name(self, name):
"""convert the given name to lowercase if it is detected as
case insensitive.
this method is only used if the dialect defines
requires_name_normalize=True.
"""
raise NotImplementedError()
def denormalize_name(self, name):
"""convert the given name to a case insensitive identifier
for the backend if it is an all-lowercase name.
this method is only used if the dialect defines
requires_name_normalize=True.
"""
raise NotImplementedError()
def has_table(self, connection, table_name, schema=None):
"""Check the existence of a particular table in the database.
Given a :class:`.Connection` object and a string
`table_name`, return True if the given table (possibly within
the specified `schema`) exists in the database, False
otherwise.
"""
raise NotImplementedError()
def has_sequence(self, connection, sequence_name, schema=None):
"""Check the existence of a particular sequence in the database.
Given a :class:`.Connection` object and a string
`sequence_name`, return True if the given sequence exists in
the database, False otherwise.
"""
raise NotImplementedError()
def _get_server_version_info(self, connection):
"""Retrieve the server version info from the given connection.
This is used by the default implementation to populate the
"server_version_info" attribute and is called exactly
once upon first connect.
"""
raise NotImplementedError()
def _get_default_schema_name(self, connection):
"""Return the string name of the currently selected schema from
the given connection.
This is used by the default implementation to populate the
"default_schema_name" attribute and is called exactly
once upon first connect.
"""
raise NotImplementedError()
def do_begin(self, connection):
"""Provide an implementation of *connection.begin()*, given a
DB-API connection."""
raise NotImplementedError()
def do_rollback(self, connection):
"""Provide an implementation of *connection.rollback()*, given
a DB-API connection."""
raise NotImplementedError()
def create_xid(self):
"""Create a two-phase transaction ID.
This id will be passed to do_begin_twophase(),
do_rollback_twophase(), do_commit_twophase(). Its format is
unspecified.
"""
raise NotImplementedError()
def do_commit(self, connection):
"""Provide an implementation of *connection.commit()*, given a
DB-API connection."""
raise NotImplementedError()
def do_savepoint(self, connection, name):
"""Create a savepoint with the given name on a SQLAlchemy
connection."""
raise NotImplementedError()
def do_rollback_to_savepoint(self, connection, name):
"""Rollback a SQL Alchemy connection to the named savepoint."""
raise NotImplementedError()
def do_release_savepoint(self, connection, name):
"""Release the named savepoint on a SQL Alchemy connection."""
raise NotImplementedError()
def do_begin_twophase(self, connection, xid):
"""Begin a two phase transaction on the given connection."""
raise NotImplementedError()
def do_prepare_twophase(self, connection, xid):
"""Prepare a two phase transaction on the given connection."""
raise NotImplementedError()
def do_rollback_twophase(self, connection, xid, is_prepared=True,
recover=False):
"""Rollback a two phase transaction on the given connection."""
raise NotImplementedError()
def do_commit_twophase(self, connection, xid, is_prepared=True,
recover=False):
"""Commit a two phase transaction on the given connection."""
raise NotImplementedError()
def do_recover_twophase(self, connection):
"""Recover list of uncommited prepared two phase transaction
identifiers on the given connection."""
raise NotImplementedError()
def do_executemany(self, cursor, statement, parameters, context=None):
"""Provide an implementation of ``cursor.executemany(statement,
parameters)``."""
raise NotImplementedError()
def do_execute(self, cursor, statement, parameters, context=None):
"""Provide an implementation of ``cursor.execute(statement,
parameters)``."""
raise NotImplementedError()
def do_execute_no_params(self, cursor, statement, parameters, context=None):
"""Provide an implementation of ``cursor.execute(statement)``.
The parameter collection should not be sent.
"""
raise NotImplementedError()
def is_disconnect(self, e, connection, cursor):
"""Return True if the given DB-API error indicates an invalid
connection"""
raise NotImplementedError()
def connect(self):
"""return a callable which sets up a newly created DBAPI connection.
The callable accepts a single argument "conn" which is the
DBAPI connection itself. It has no return value.
This is used to set dialect-wide per-connection options such as
isolation modes, unicode modes, etc.
If a callable is returned, it will be assembled into a pool listener
that receives the direct DBAPI connection, with all wrappers removed.
If None is returned, no listener will be generated.
"""
return None
def reset_isolation_level(self, dbapi_conn):
"""Given a DBAPI connection, revert its isolation to the default."""
raise NotImplementedError()
def set_isolation_level(self, dbapi_conn, level):
"""Given a DBAPI connection, set its isolation level."""
raise NotImplementedError()
def get_isolation_level(self, dbapi_conn):
"""Given a DBAPI connection, return its isolation level."""
raise NotImplementedError()
class ExecutionContext(object):
"""A messenger object for a Dialect that corresponds to a single
execution.
ExecutionContext should have these data members:
connection
Connection object which can be freely used by default value
generators to execute SQL. This Connection should reference the
same underlying connection/transactional resources of
root_connection.
root_connection
Connection object which is the source of this ExecutionContext. This
Connection may have close_with_result=True set, in which case it can
only be used once.
dialect
dialect which created this ExecutionContext.
cursor
DB-API cursor procured from the connection,
compiled
if passed to constructor, sqlalchemy.engine.base.Compiled object
being executed,
statement
string version of the statement to be executed. Is either
passed to the constructor, or must be created from the
sql.Compiled object by the time pre_exec() has completed.
parameters
bind parameters passed to the execute() method. For compiled
statements, this is a dictionary or list of dictionaries. For
textual statements, it should be in a format suitable for the
dialect's paramstyle (i.e. dict or list of dicts for non
positional, list or list of lists/tuples for positional).
isinsert
True if the statement is an INSERT.
isupdate
True if the statement is an UPDATE.
should_autocommit
True if the statement is a "committable" statement.
postfetch_cols
a list of Column objects for which a server-side default or
inline SQL expression value was fired off. Applies to inserts
and updates.
"""
def create_cursor(self):
"""Return a new cursor generated from this ExecutionContext's
connection.
Some dialects may wish to change the behavior of
connection.cursor(), such as postgresql which may return a PG
"server side" cursor.
"""
raise NotImplementedError()
def pre_exec(self):
"""Called before an execution of a compiled statement.
If a compiled statement was passed to this ExecutionContext,
the `statement` and `parameters` datamembers must be
initialized after this statement is complete.
"""
raise NotImplementedError()
def post_exec(self):
"""Called after the execution of a compiled statement.
If a compiled statement was passed to this ExecutionContext,
the `last_insert_ids`, `last_inserted_params`, etc.
datamembers should be available after this method completes.
"""
raise NotImplementedError()
def result(self):
"""Return a result object corresponding to this ExecutionContext.
Returns a ResultProxy.
"""
raise NotImplementedError()
def handle_dbapi_exception(self, e):
"""Receive a DBAPI exception which occurred upon execute, result
fetch, etc."""
raise NotImplementedError()
def should_autocommit_text(self, statement):
"""Parse the given textual statement and return True if it refers to
a "committable" statement"""
raise NotImplementedError()
def lastrow_has_defaults(self):
"""Return True if the last INSERT or UPDATE row contained
inlined or database-side defaults.
"""
raise NotImplementedError()
def get_rowcount(self):
"""Return the number of rows produced (by a SELECT query)
or affected (by an INSERT/UPDATE/DELETE statement).
Note that this row count may not be properly implemented
in some dialects; this is indicated by the
``supports_sane_rowcount`` and ``supports_sane_multi_rowcount``
dialect attributes.
"""
raise NotImplementedError()
class Compiled(object):
"""Represent a compiled SQL or DDL expression.
The ``__str__`` method of the ``Compiled`` object should produce
the actual text of the statement. ``Compiled`` objects are
specific to their underlying database dialect, and also may
or may not be specific to the columns referenced within a
particular set of bind parameters. In no case should the
``Compiled`` object be dependent on the actual values of those
bind parameters, even though it may reference those values as
defaults.
"""
def __init__(self, dialect, statement, bind=None):
"""Construct a new ``Compiled`` object.
:param dialect: ``Dialect`` to compile against.
:param statement: ``ClauseElement`` to be compiled.
:param bind: Optional Engine or Connection to compile this
statement against.
"""
self.dialect = dialect
self.bind = bind
if statement is not None:
self.statement = statement
self.can_execute = statement.supports_execution
self.string = self.process(self.statement)
@util.deprecated("0.7", ":class:`.Compiled` objects now compile "
"within the constructor.")
def compile(self):
"""Produce the internal string representation of this element."""
pass
@property
def sql_compiler(self):
"""Return a Compiled that is capable of processing SQL expressions.
If this compiler is one, it would likely just return 'self'.
"""
raise NotImplementedError()
def process(self, obj, **kwargs):
return obj._compiler_dispatch(self, **kwargs)
def __str__(self):
"""Return the string text of the generated SQL or DDL."""
return self.string or ''
def construct_params(self, params=None):
"""Return the bind params for this compiled object.
:param params: a dict of string/object pairs whos values will
override bind values compiled in to the
statement.
"""
raise NotImplementedError()
@property
def params(self):
"""Return the bind params for this compiled object."""
return self.construct_params()
def execute(self, *multiparams, **params):
"""Execute this compiled object."""
e = self.bind
if e is None:
raise exc.UnboundExecutionError(
"This Compiled object is not bound to any Engine "
"or Connection.")
return e._execute_compiled(self, multiparams, params)
def scalar(self, *multiparams, **params):
"""Execute this compiled object and return the result's
scalar value."""
return self.execute(*multiparams, **params).scalar()
class TypeCompiler(object):
"""Produces DDL specification for TypeEngine objects."""
def __init__(self, dialect):
self.dialect = dialect
def process(self, type_):
return type_._compiler_dispatch(self)
class Connectable(object):
"""Interface for an object which supports execution of SQL constructs.
The two implementations of :class:`.Connectable` are :class:`.Connection` and
:class:`.Engine`.
Connectable must also implement the 'dialect' member which references a
:class:`.Dialect` instance.
"""
def connect(self, **kwargs):
"""Return a :class:`.Connection` object.
Depending on context, this may be ``self`` if this object
is already an instance of :class:`.Connection`, or a newly
procured :class:`.Connection` if this object is an instance
of :class:`.Engine`.
"""
def contextual_connect(self):
"""Return a :class:`.Connection` object which may be part of an ongoing
context.
Depending on context, this may be ``self`` if this object
is already an instance of :class:`.Connection`, or a newly
procured :class:`.Connection` if this object is an instance
of :class:`.Engine`.
"""
raise NotImplementedError()
@util.deprecated("0.7", "Use the create() method on the given schema "
"object directly, i.e. :meth:`.Table.create`, "
":meth:`.Index.create`, :meth:`.MetaData.create_all`")
def create(self, entity, **kwargs):
"""Emit CREATE statements for the given schema entity."""
raise NotImplementedError()
@util.deprecated("0.7", "Use the drop() method on the given schema "
"object directly, i.e. :meth:`.Table.drop`, "
":meth:`.Index.drop`, :meth:`.MetaData.drop_all`")
def drop(self, entity, **kwargs):
"""Emit DROP statements for the given schema entity."""
raise NotImplementedError()
def execute(self, object, *multiparams, **params):
"""Executes the given construct and returns a :class:`.ResultProxy`."""
raise NotImplementedError()
def scalar(self, object, *multiparams, **params):
"""Executes and returns the first column of the first row.
The underlying cursor is closed after execution.
"""
raise NotImplementedError()
def _run_visitor(self, visitorcallable, element,
**kwargs):
raise NotImplementedError()
def _execute_clauseelement(self, elem, multiparams=None, params=None):
raise NotImplementedError()
class Connection(Connectable):
"""Provides high-level functionality for a wrapped DB-API connection.
Provides execution support for string-based SQL statements as well as
:class:`.ClauseElement`, :class:`.Compiled` and :class:`.DefaultGenerator`
objects. Provides a :meth:`begin` method to return :class:`.Transaction`
objects.
The Connection object is **not** thread-safe. While a Connection can be
shared among threads using properly synchronized access, it is still
possible that the underlying DBAPI connection may not support shared
access between threads. Check the DBAPI documentation for details.
The Connection object represents a single dbapi connection checked out
from the connection pool. In this state, the connection pool has no affect
upon the connection, including its expiration or timeout state. For the
connection pool to properly manage connections, connections should be
returned to the connection pool (i.e. ``connection.close()``) whenever the
connection is not in use.
.. index::
single: thread safety; Connection
"""
def __init__(self, engine, connection=None, close_with_result=False,
_branch=False, _execution_options=None):
"""Construct a new Connection.
The constructor here is not public and is only called only by an
:class:`.Engine`. See :meth:`.Engine.connect` and
:meth:`.Engine.contextual_connect` methods.
"""
self.engine = engine
self.dialect = engine.dialect
self.__connection = connection or engine.raw_connection()
self.__transaction = None
self.should_close_with_result = close_with_result
self.__savepoint_seq = 0
self.__branch = _branch
self.__invalid = False
self._has_events = engine._has_events
self._echo = self.engine._should_log_info()
if _execution_options:
self._execution_options =\
engine._execution_options.union(_execution_options)
else:
self._execution_options = engine._execution_options
def _branch(self):
"""Return a new Connection which references this Connection's
engine and connection; but does not have close_with_result enabled,
and also whose close() method does nothing.
This is used to execute "sub" statements within a single execution,
usually an INSERT statement.
"""
return self.engine._connection_cls(
self.engine,
self.__connection, _branch=True)
def _clone(self):
"""Create a shallow copy of this Connection.
"""
c = self.__class__.__new__(self.__class__)
c.__dict__ = self.__dict__.copy()
return c
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
self.close()
def execution_options(self, **opt):
""" Set non-SQL options for the connection which take effect
during execution.
The method returns a copy of this :class:`.Connection` which references
the same underlying DBAPI connection, but also defines the given
execution options which will take effect for a call to
:meth:`execute`. As the new :class:`.Connection` references the same
underlying resource, it is probably best to ensure that the copies
would be discarded immediately, which is implicit if used as in::
result = connection.execution_options(stream_results=True).\\
execute(stmt)
:meth:`.Connection.execution_options` accepts all options as those
accepted by :meth:`.Executable.execution_options`. Additionally,
it includes options that are applicable only to
:class:`.Connection`.
:param autocommit: Available on: Connection, statement.
When True, a COMMIT will be invoked after execution
when executed in 'autocommit' mode, i.e. when an explicit
transaction is not begun on the connection. Note that DBAPI
connections by default are always in a transaction - SQLAlchemy uses
rules applied to different kinds of statements to determine if
COMMIT will be invoked in order to provide its "autocommit" feature.
Typically, all INSERT/UPDATE/DELETE statements as well as
CREATE/DROP statements have autocommit behavior enabled; SELECT
constructs do not. Use this option when invoking a SELECT or other
specific SQL construct where COMMIT is desired (typically when
calling stored procedures and such), and an explicit
transaction is not in progress.
:param compiled_cache: Available on: Connection.
A dictionary where :class:`.Compiled` objects
will be cached when the :class:`.Connection` compiles a clause
expression into a :class:`.Compiled` object.
It is the user's responsibility to
manage the size of this dictionary, which will have keys
corresponding to the dialect, clause element, the column
names within the VALUES or SET clause of an INSERT or UPDATE,
as well as the "batch" mode for an INSERT or UPDATE statement.
The format of this dictionary is not guaranteed to stay the
same in future releases.
Note that the ORM makes use of its own "compiled" caches for
some operations, including flush operations. The caching
used by the ORM internally supersedes a cache dictionary
specified here.
:param isolation_level: Available on: Connection.
Set the transaction isolation level for
the lifespan of this connection. Valid values include
those string values accepted by the ``isolation_level``
parameter passed to :func:`.create_engine`, and are
database specific, including those for :ref:`sqlite_toplevel`,
:ref:`postgresql_toplevel` - see those dialect's documentation
for further info.
Note that this option necessarily affects the underying
DBAPI connection for the lifespan of the originating
:class:`.Connection`, and is not per-execution. This
setting is not removed until the underying DBAPI connection
is returned to the connection pool, i.e.
the :meth:`.Connection.close` method is called.
:param no_parameters: When ``True``, if the final parameter
list or dictionary is totally empty, will invoke the
statement on the cursor as ``cursor.execute(statement)``,
not passing the parameter collection at all.
Some DBAPIs such as psycopg2 and mysql-python consider
percent signs as significant only when parameters are
present; this option allows code to generate SQL
containing percent signs (and possibly other characters)
that is neutral regarding whether it's executed by the DBAPI
or piped into a script that's later invoked by
command line tools. New in 0.7.6.
:param stream_results: Available on: Connection, statement.
Indicate to the dialect that results should be
"streamed" and not pre-buffered, if possible. This is a limitation
of many DBAPIs. The flag is currently understood only by the
psycopg2 dialect.
"""
c = self._clone()
c._execution_options = c._execution_options.union(opt)
if 'isolation_level' in opt:
c._set_isolation_level()
return c
def _set_isolation_level(self):
self.dialect.set_isolation_level(self.connection,
self._execution_options['isolation_level'])
self.connection._connection_record.finalize_callback = \
self.dialect.reset_isolation_level
@property
def closed(self):
"""Return True if this connection is closed."""
return not self.__invalid and '_Connection__connection' \
not in self.__dict__
@property
def invalidated(self):
"""Return True if this connection was invalidated."""
return self.__invalid
@property
def connection(self):
"The underlying DB-API connection managed by this Connection."
try:
return self.__connection
except AttributeError:
return self._revalidate_connection()
def _revalidate_connection(self):
if self.__invalid:
if self.__transaction is not None:
raise exc.InvalidRequestError(
"Can't reconnect until invalid "
"transaction is rolled back")
self.__connection = self.engine.raw_connection()
self.__invalid = False
return self.__connection
raise exc.ResourceClosedError("This Connection is closed")
@property
def _connection_is_valid(self):
# use getattr() for is_valid to support exceptions raised in
# dialect initializer, where the connection is not wrapped in
# _ConnectionFairy
return getattr(self.__connection, 'is_valid', False)
@property
def _still_open_and_connection_is_valid(self):
return \
not self.closed and \
not self.invalidated and \
getattr(self.__connection, 'is_valid', False)
@property
def info(self):
"""A collection of per-DB-API connection instance properties."""
return self.connection.info
def connect(self):
"""Returns self.
This ``Connectable`` interface method returns self, allowing
Connections to be used interchangably with Engines in most
situations that require a bind.
"""
return self
def contextual_connect(self, **kwargs):
"""Returns self.
This ``Connectable`` interface method returns self, allowing
Connections to be used interchangably with Engines in most
situations that require a bind.
"""
return self
def invalidate(self, exception=None):
"""Invalidate the underlying DBAPI connection associated with
this Connection.
The underlying DB-API connection is literally closed (if
possible), and is discarded. Its source connection pool will
typically lazily create a new connection to replace it.
Upon the next usage, this Connection will attempt to reconnect
to the pool with a new connection.
Transactions in progress remain in an "opened" state (even though the
actual transaction is gone); these must be explicitly rolled back
before a reconnect on this Connection can proceed. This is to prevent
applications from accidentally continuing their transactional
operations in a non-transactional state.
"""
if self.invalidated:
return
if self.closed:
raise exc.ResourceClosedError("This Connection is closed")
if self._connection_is_valid:
self.__connection.invalidate(exception)
del self.__connection
self.__invalid = True
def detach(self):
"""Detach the underlying DB-API connection from its connection pool.
This Connection instance will remain useable. When closed,
the DB-API connection will be literally closed and not
returned to its pool. The pool will typically lazily create a
new connection to replace the detached connection.
This method can be used to insulate the rest of an application
from a modified state on a connection (such as a transaction
isolation level or similar). Also see
:class:`~sqlalchemy.interfaces.PoolListener` for a mechanism to modify
connection state when connections leave and return to their
connection pool.
"""
self.__connection.detach()
def begin(self):
"""Begin a transaction and return a transaction handle.
The returned object is an instance of :class:`.Transaction`.
This object represents the "scope" of the transaction,
which completes when either the :meth:`.Transaction.rollback`
or :meth:`.Transaction.commit` method is called.
Nested calls to :meth:`.begin` on the same :class:`.Connection`
will return new :class:`.Transaction` objects that represent
an emulated transaction within the scope of the enclosing
transaction, that is::
trans = conn.begin() # outermost transaction
trans2 = conn.begin() # "nested"
trans2.commit() # does nothing
trans.commit() # actually commits
Calls to :meth:`.Transaction.commit` only have an effect
when invoked via the outermost :class:`.Transaction` object, though the
:meth:`.Transaction.rollback` method of any of the
:class:`.Transaction` objects will roll back the
transaction.
See also:
:meth:`.Connection.begin_nested` - use a SAVEPOINT
:meth:`.Connection.begin_twophase` - use a two phase /XID transaction
:meth:`.Engine.begin` - context manager available from :class:`.Engine`.
"""
if self.__transaction is None:
self.__transaction = RootTransaction(self)
return self.__transaction
else:
return Transaction(self, self.__transaction)
def begin_nested(self):
"""Begin a nested transaction and return a transaction handle.
The returned object is an instance of :class:`.NestedTransaction`.
Nested transactions require SAVEPOINT support in the
underlying database. Any transaction in the hierarchy may
``commit`` and ``rollback``, however the outermost transaction
still controls the overall ``commit`` or ``rollback`` of the
transaction of a whole.
See also :meth:`.Connection.begin`,
:meth:`.Connection.begin_twophase`.
"""
if self.__transaction is None:
self.__transaction = RootTransaction(self)
else:
self.__transaction = NestedTransaction(self, self.__transaction)
return self.__transaction
def begin_twophase(self, xid=None):
"""Begin a two-phase or XA transaction and return a transaction
handle.
The returned object is an instance of :class:`.TwoPhaseTransaction`,
which in addition to the methods provided by
:class:`.Transaction`, also provides a :meth:`~.TwoPhaseTransaction.prepare`
method.
:param xid: the two phase transaction id. If not supplied, a
random id will be generated.
See also :meth:`.Connection.begin`,
:meth:`.Connection.begin_twophase`.
"""
if self.__transaction is not None:
raise exc.InvalidRequestError(
"Cannot start a two phase transaction when a transaction "
"is already in progress.")
if xid is None:
xid = self.engine.dialect.create_xid();
self.__transaction = TwoPhaseTransaction(self, xid)
return self.__transaction
def recover_twophase(self):
return self.engine.dialect.do_recover_twophase(self)
def rollback_prepared(self, xid, recover=False):
self.engine.dialect.do_rollback_twophase(self, xid, recover=recover)
def commit_prepared(self, xid, recover=False):
self.engine.dialect.do_commit_twophase(self, xid, recover=recover)
def in_transaction(self):
"""Return True if a transaction is in progress."""
return self.__transaction is not None
def _begin_impl(self):
if self._echo:
self.engine.logger.info("BEGIN (implicit)")
if self._has_events:
self.engine.dispatch.begin(self)
try:
self.engine.dialect.do_begin(self.connection)
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
def _rollback_impl(self):
if self._has_events:
self.engine.dispatch.rollback(self)
if self._still_open_and_connection_is_valid:
if self._echo:
self.engine.logger.info("ROLLBACK")
try:
self.engine.dialect.do_rollback(self.connection)
self.__transaction = None
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
else:
self.__transaction = None
def _commit_impl(self):
if self._has_events:
self.engine.dispatch.commit(self)
if self._echo:
self.engine.logger.info("COMMIT")
try:
self.engine.dialect.do_commit(self.connection)
self.__transaction = None
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
def _savepoint_impl(self, name=None):
if self._has_events:
self.engine.dispatch.savepoint(self, name)
if name is None:
self.__savepoint_seq += 1
name = 'sa_savepoint_%s' % self.__savepoint_seq
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_savepoint(self, name)
return name
def _rollback_to_savepoint_impl(self, name, context):
if self._has_events:
self.engine.dispatch.rollback_savepoint(self, name, context)
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_rollback_to_savepoint(self, name)
self.__transaction = context
def _release_savepoint_impl(self, name, context):
if self._has_events:
self.engine.dispatch.release_savepoint(self, name, context)
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_release_savepoint(self, name)
self.__transaction = context
def _begin_twophase_impl(self, xid):
if self._has_events:
self.engine.dispatch.begin_twophase(self, xid)
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_begin_twophase(self, xid)
def _prepare_twophase_impl(self, xid):
if self._has_events:
self.engine.dispatch.prepare_twophase(self, xid)
if self._still_open_and_connection_is_valid:
assert isinstance(self.__transaction, TwoPhaseTransaction)
self.engine.dialect.do_prepare_twophase(self, xid)
def _rollback_twophase_impl(self, xid, is_prepared):
if self._has_events:
self.engine.dispatch.rollback_twophase(self, xid, is_prepared)
if self._still_open_and_connection_is_valid:
assert isinstance(self.__transaction, TwoPhaseTransaction)
self.engine.dialect.do_rollback_twophase(self, xid, is_prepared)
self.__transaction = None
def _commit_twophase_impl(self, xid, is_prepared):
if self._has_events:
self.engine.dispatch.commit_twophase(self, xid, is_prepared)
if self._still_open_and_connection_is_valid:
assert isinstance(self.__transaction, TwoPhaseTransaction)
self.engine.dialect.do_commit_twophase(self, xid, is_prepared)
self.__transaction = None
def _autorollback(self):
if not self.in_transaction():
self._rollback_impl()
def close(self):
"""Close this :class:`.Connection`.
This results in a release of the underlying database
resources, that is, the DBAPI connection referenced
internally. The DBAPI connection is typically restored
back to the connection-holding :class:`.Pool` referenced
by the :class:`.Engine` that produced this
:class:`.Connection`. Any transactional state present on
the DBAPI connection is also unconditionally released via
the DBAPI connection's ``rollback()`` method, regardless
of any :class:`.Transaction` object that may be
outstanding with regards to this :class:`.Connection`.
After :meth:`~.Connection.close` is called, the
:class:`.Connection` is permanently in a closed state,
and will allow no further operations.
"""
try:
conn = self.__connection
except AttributeError:
return
if not self.__branch:
conn.close()
self.__invalid = False
del self.__connection
self.__transaction = None
def scalar(self, object, *multiparams, **params):
"""Executes and returns the first column of the first row.
The underlying result/cursor is closed after execution.
"""
return self.execute(object, *multiparams, **params).scalar()
def execute(self, object, *multiparams, **params):
"""Executes the a SQL statement construct and returns a :class:`.ResultProxy`.
:param object: The statement to be executed. May be
one of:
* a plain string
* any :class:`.ClauseElement` construct that is also
a subclass of :class:`.Executable`, such as a
:func:`~.expression.select` construct
* a :class:`.FunctionElement`, such as that generated
by :attr:`.func`, will be automatically wrapped in
a SELECT statement, which is then executed.
* a :class:`.DDLElement` object
* a :class:`.DefaultGenerator` object
* a :class:`.Compiled` object
:param \*multiparams/\**params: represent bound parameter
values to be used in the execution. Typically,
the format is either a collection of one or more
dictionaries passed to \*multiparams::
conn.execute(
table.insert(),
{"id":1, "value":"v1"},
{"id":2, "value":"v2"}
)
...or individual key/values interpreted by \**params::
conn.execute(
table.insert(), id=1, value="v1"
)
In the case that a plain SQL string is passed, and the underlying
DBAPI accepts positional bind parameters, a collection of tuples
or individual values in \*multiparams may be passed::
conn.execute(
"INSERT INTO table (id, value) VALUES (?, ?)",
(1, "v1"), (2, "v2")
)
conn.execute(
"INSERT INTO table (id, value) VALUES (?, ?)",
1, "v1"
)
Note above, the usage of a question mark "?" or other
symbol is contingent upon the "paramstyle" accepted by the DBAPI
in use, which may be any of "qmark", "named", "pyformat", "format",
"numeric". See `pep-249 <http://www.python.org/dev/peps/pep-0249/>`_
for details on paramstyle.
To execute a textual SQL statement which uses bound parameters in a
DBAPI-agnostic way, use the :func:`~.expression.text` construct.
"""
for c in type(object).__mro__:
if c in Connection.executors:
return Connection.executors[c](
self,
object,
multiparams,
params)
else:
raise exc.InvalidRequestError(
"Unexecutable object type: %s" %
type(object))
def __distill_params(self, multiparams, params):
"""Given arguments from the calling form *multiparams, **params,
return a list of bind parameter structures, usually a list of
dictionaries.
In the case of 'raw' execution which accepts positional parameters,
it may be a list of tuples or lists.
"""
if not multiparams:
if params:
return [params]
else:
return []
elif len(multiparams) == 1:
zero = multiparams[0]
if isinstance(zero, (list, tuple)):
if not zero or hasattr(zero[0], '__iter__'):
return zero
else:
return [zero]
elif hasattr(zero, 'keys'):
return [zero]
else:
return [[zero]]
else:
if hasattr(multiparams[0], '__iter__'):
return multiparams
else:
return [multiparams]
def _execute_function(self, func, multiparams, params):
"""Execute a sql.FunctionElement object."""
return self._execute_clauseelement(func.select(),
multiparams, params)
def _execute_default(self, default, multiparams, params):
"""Execute a schema.ColumnDefault object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
default, multiparams, params = \
fn(self, default, multiparams, params)
try:
try:
conn = self.__connection
except AttributeError:
conn = self._revalidate_connection()
dialect = self.dialect
ctx = dialect.execution_ctx_cls._init_default(
dialect, self, conn)
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
ret = ctx._exec_default(default, None)
if self.should_close_with_result:
self.close()
if self._has_events:
self.engine.dispatch.after_execute(self,
default, multiparams, params, ret)
return ret
def _execute_ddl(self, ddl, multiparams, params):
"""Execute a schema.DDL object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
ddl, multiparams, params = \
fn(self, ddl, multiparams, params)
dialect = self.dialect
compiled = ddl.compile(dialect=dialect)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_ddl,
compiled,
None,
compiled
)
if self._has_events:
self.engine.dispatch.after_execute(self,
ddl, multiparams, params, ret)
return ret
def _execute_clauseelement(self, elem, multiparams, params):
"""Execute a sql.ClauseElement object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
elem, multiparams, params = \
fn(self, elem, multiparams, params)
distilled_params = self.__distill_params(multiparams, params)
if distilled_params:
keys = distilled_params[0].keys()
else:
keys = []
dialect = self.dialect
if 'compiled_cache' in self._execution_options:
key = dialect, elem, tuple(keys), len(distilled_params) > 1
if key in self._execution_options['compiled_cache']:
compiled_sql = self._execution_options['compiled_cache'][key]
else:
compiled_sql = elem.compile(
dialect=dialect, column_keys=keys,
inline=len(distilled_params) > 1)
self._execution_options['compiled_cache'][key] = compiled_sql
else:
compiled_sql = elem.compile(
dialect=dialect, column_keys=keys,
inline=len(distilled_params) > 1)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_compiled,
compiled_sql,
distilled_params,
compiled_sql, distilled_params
)
if self._has_events:
self.engine.dispatch.after_execute(self,
elem, multiparams, params, ret)
return ret
def _execute_compiled(self, compiled, multiparams, params):
"""Execute a sql.Compiled object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
compiled, multiparams, params = \
fn(self, compiled, multiparams, params)
dialect = self.dialect
parameters=self.__distill_params(multiparams, params)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_compiled,
compiled,
parameters,
compiled, parameters
)
if self._has_events:
self.engine.dispatch.after_execute(self,
compiled, multiparams, params, ret)
return ret
def _execute_text(self, statement, multiparams, params):
"""Execute a string SQL statement."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
statement, multiparams, params = \
fn(self, statement, multiparams, params)
dialect = self.dialect
parameters = self.__distill_params(multiparams, params)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_statement,
statement,
parameters,
statement, parameters
)
if self._has_events:
self.engine.dispatch.after_execute(self,
statement, multiparams, params, ret)
return ret
def _execute_context(self, dialect, constructor,
statement, parameters,
*args):
"""Create an :class:`.ExecutionContext` and execute, returning
a :class:`.ResultProxy`."""
try:
try:
conn = self.__connection
except AttributeError:
conn = self._revalidate_connection()
context = constructor(dialect, self, conn, *args)
except Exception, e:
self._handle_dbapi_exception(e,
str(statement), parameters,
None, None)
raise
if context.compiled:
context.pre_exec()
cursor, statement, parameters = context.cursor, \
context.statement, \
context.parameters
if not context.executemany:
parameters = parameters[0]
if self._has_events:
for fn in self.engine.dispatch.before_cursor_execute:
statement, parameters = \
fn(self, cursor, statement, parameters,
context, context.executemany)
if self._echo:
self.engine.logger.info(statement)
self.engine.logger.info("%r",
sql_util._repr_params(parameters, batches=10))
try:
if context.executemany:
self.dialect.do_executemany(
cursor,
statement,
parameters,
context)
elif not parameters and context.no_parameters:
self.dialect.do_execute_no_params(
cursor,
statement,
context)
else:
self.dialect.do_execute(
cursor,
statement,
parameters,
context)
except Exception, e:
self._handle_dbapi_exception(
e,
statement,
parameters,
cursor,
context)
raise
if self._has_events:
self.engine.dispatch.after_cursor_execute(self, cursor,
statement,
parameters,
context,
context.executemany)
if context.compiled:
context.post_exec()
if context.isinsert and not context.executemany:
context.post_insert()
# create a resultproxy, get rowcount/implicit RETURNING
# rows, close cursor if no further results pending
result = context.get_result_proxy()
if context.isinsert:
if context._is_implicit_returning:
context._fetch_implicit_returning(result)
result.close(_autoclose_connection=False)
elif not context._is_explicit_returning:
result.close(_autoclose_connection=False)
elif result._metadata is None:
# no results, get rowcount
# (which requires open cursor on some drivers
# such as kintersbasdb, mxodbc),
result.rowcount
result.close(_autoclose_connection=False)
if self.__transaction is None and context.should_autocommit:
self._commit_impl()
if result.closed and self.should_close_with_result:
self.close()
return result
def _cursor_execute(self, cursor, statement, parameters):
"""Execute a statement + params on the given cursor.
Adds appropriate logging and exception handling.
This method is used by DefaultDialect for special-case
executions, such as for sequences and column defaults.
The path of statement execution in the majority of cases
terminates at _execute_context().
"""
if self._echo:
self.engine.logger.info(statement)
self.engine.logger.info("%r", parameters)
try:
self.dialect.do_execute(
cursor,
statement,
parameters)
except Exception, e:
self._handle_dbapi_exception(
e,
statement,
parameters,
cursor,
None)
raise
def _safe_close_cursor(self, cursor):
"""Close the given cursor, catching exceptions
and turning into log warnings.
"""
try:
cursor.close()
except Exception, e:
try:
ex_text = str(e)
except TypeError:
ex_text = repr(e)
self.connection._logger.warn("Error closing cursor: %s", ex_text)
if isinstance(e, (SystemExit, KeyboardInterrupt)):
raise
def _handle_dbapi_exception(self,
e,
statement,
parameters,
cursor,
context):
if getattr(self, '_reentrant_error', False):
# Py3K
#raise exc.DBAPIError.instance(statement, parameters, e,
# self.dialect.dbapi.Error) from e
# Py2K
raise exc.DBAPIError.instance(statement,
parameters,
e,
self.dialect.dbapi.Error), \
None, sys.exc_info()[2]
# end Py2K
self._reentrant_error = True
try:
# non-DBAPI error - if we already got a context,
# or theres no string statement, don't wrap it
should_wrap = isinstance(e, self.dialect.dbapi.Error) or \
(statement is not None and context is None)
if should_wrap and context:
context.handle_dbapi_exception(e)
is_disconnect = isinstance(e, self.dialect.dbapi.Error) and \
self.dialect.is_disconnect(e, self.__connection, cursor)
if is_disconnect:
self.invalidate(e)
self.engine.dispose()
else:
if cursor:
self._safe_close_cursor(cursor)
self._autorollback()
if self.should_close_with_result:
self.close()
if not should_wrap:
return
# Py3K
#raise exc.DBAPIError.instance(
# statement,
# parameters,
# e,
# self.dialect.dbapi.Error,
# connection_invalidated=is_disconnect) \
# from e
# Py2K
raise exc.DBAPIError.instance(
statement,
parameters,
e,
self.dialect.dbapi.Error,
connection_invalidated=is_disconnect), \
None, sys.exc_info()[2]
# end Py2K
finally:
del self._reentrant_error
# poor man's multimethod/generic function thingy
executors = {
expression.FunctionElement: _execute_function,
expression.ClauseElement: _execute_clauseelement,
Compiled: _execute_compiled,
schema.SchemaItem: _execute_default,
schema.DDLElement: _execute_ddl,
basestring: _execute_text
}
@util.deprecated("0.7", "Use the create() method on the given schema "
"object directly, i.e. :meth:`.Table.create`, "
":meth:`.Index.create`, :meth:`.MetaData.create_all`")
def create(self, entity, **kwargs):
"""Emit CREATE statements for the given schema entity."""
return self.engine.create(entity, connection=self, **kwargs)
@util.deprecated("0.7", "Use the drop() method on the given schema "
"object directly, i.e. :meth:`.Table.drop`, "
":meth:`.Index.drop`, :meth:`.MetaData.drop_all`")
def drop(self, entity, **kwargs):
"""Emit DROP statements for the given schema entity."""
return self.engine.drop(entity, connection=self, **kwargs)
@util.deprecated("0.7", "Use autoload=True with :class:`.Table`, "
"or use the :class:`.Inspector` object.")
def reflecttable(self, table, include_columns=None):
"""Load table description from the database.
Given a :class:`.Table` object, reflect its columns and
properties from the database, populating the given :class:`.Table`
object with attributes.. If include_columns (a list or
set) is specified, limit the autoload to the given column
names.
The default implementation uses the
:class:`.Inspector` interface to
provide the output, building upon the granular table/column/
constraint etc. methods of :class:`.Dialect`.
"""
return self.engine.reflecttable(table, self, include_columns)
def default_schema_name(self):
return self.engine.dialect.get_default_schema_name(self)
def transaction(self, callable_, *args, **kwargs):
"""Execute the given function within a transaction boundary.
The function is passed this :class:`.Connection`
as the first argument, followed by the given \*args and \**kwargs,
e.g.::
def do_something(conn, x, y):
conn.execute("some statement", {'x':x, 'y':y})
conn.transaction(do_something, 5, 10)
The operations inside the function are all invoked within the
context of a single :class:`.Transaction`.
Upon success, the transaction is committed. If an
exception is raised, the transaction is rolled back
before propagating the exception.
.. note::
The :meth:`.transaction` method is superseded by
the usage of the Python ``with:`` statement, which can
be used with :meth:`.Connection.begin`::
with conn.begin():
conn.execute("some statement", {'x':5, 'y':10})
As well as with :meth:`.Engine.begin`::
with engine.begin() as conn:
conn.execute("some statement", {'x':5, 'y':10})
See also:
:meth:`.Engine.begin` - engine-level transactional
context
:meth:`.Engine.transaction` - engine-level version of
:meth:`.Connection.transaction`
"""
trans = self.begin()
try:
ret = self.run_callable(callable_, *args, **kwargs)
trans.commit()
return ret
except:
trans.rollback()
raise
def run_callable(self, callable_, *args, **kwargs):
"""Given a callable object or function, execute it, passing
a :class:`.Connection` as the first argument.
The given \*args and \**kwargs are passed subsequent
to the :class:`.Connection` argument.
This function, along with :meth:`.Engine.run_callable`,
allows a function to be run with a :class:`.Connection`
or :class:`.Engine` object without the need to know
which one is being dealt with.
"""
return callable_(self, *args, **kwargs)
def _run_visitor(self, visitorcallable, element, **kwargs):
visitorcallable(self.dialect, self,
**kwargs).traverse_single(element)
class Transaction(object):
"""Represent a database transaction in progress.
The :class:`.Transaction` object is procured by
calling the :meth:`~.Connection.begin` method of
:class:`.Connection`::
from sqlalchemy import create_engine
engine = create_engine("postgresql://scott:tiger@localhost/test")
connection = engine.connect()
trans = connection.begin()
connection.execute("insert into x (a, b) values (1, 2)")
trans.commit()
The object provides :meth:`.rollback` and :meth:`.commit`
methods in order to control transaction boundaries. It
also implements a context manager interface so that
the Python ``with`` statement can be used with the
:meth:`.Connection.begin` method::
with connection.begin():
connection.execute("insert into x (a, b) values (1, 2)")
The Transaction object is **not** threadsafe.
See also: :meth:`.Connection.begin`, :meth:`.Connection.begin_twophase`,
:meth:`.Connection.begin_nested`.
.. index::
single: thread safety; Transaction
"""
def __init__(self, connection, parent):
self.connection = connection
self._parent = parent or self
self.is_active = True
def close(self):
"""Close this :class:`.Transaction`.
If this transaction is the base transaction in a begin/commit
nesting, the transaction will rollback(). Otherwise, the
method returns.
This is used to cancel a Transaction without affecting the scope of
an enclosing transaction.
"""
if not self._parent.is_active:
return
if self._parent is self:
self.rollback()
def rollback(self):
"""Roll back this :class:`.Transaction`.
"""
if not self._parent.is_active:
return
self._do_rollback()
self.is_active = False
def _do_rollback(self):
self._parent.rollback()
def commit(self):
"""Commit this :class:`.Transaction`."""
if not self._parent.is_active:
raise exc.InvalidRequestError("This transaction is inactive")
self._do_commit()
self.is_active = False
def _do_commit(self):
pass
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
if type is None and self.is_active:
try:
self.commit()
except:
self.rollback()
raise
else:
self.rollback()
class RootTransaction(Transaction):
def __init__(self, connection):
super(RootTransaction, self).__init__(connection, None)
self.connection._begin_impl()
def _do_rollback(self):
if self.is_active:
self.connection._rollback_impl()
def _do_commit(self):
if self.is_active:
self.connection._commit_impl()
class NestedTransaction(Transaction):
"""Represent a 'nested', or SAVEPOINT transaction.
A new :class:`.NestedTransaction` object may be procured
using the :meth:`.Connection.begin_nested` method.
The interface is the same as that of :class:`.Transaction`.
"""
def __init__(self, connection, parent):
super(NestedTransaction, self).__init__(connection, parent)
self._savepoint = self.connection._savepoint_impl()
def _do_rollback(self):
if self.is_active:
self.connection._rollback_to_savepoint_impl(
self._savepoint, self._parent)
def _do_commit(self):
if self.is_active:
self.connection._release_savepoint_impl(
self._savepoint, self._parent)
class TwoPhaseTransaction(Transaction):
"""Represent a two-phase transaction.
A new :class:`.TwoPhaseTransaction` object may be procured
using the :meth:`.Connection.begin_twophase` method.
The interface is the same as that of :class:`.Transaction`
with the addition of the :meth:`prepare` method.
"""
def __init__(self, connection, xid):
super(TwoPhaseTransaction, self).__init__(connection, None)
self._is_prepared = False
self.xid = xid
self.connection._begin_twophase_impl(self.xid)
def prepare(self):
"""Prepare this :class:`.TwoPhaseTransaction`.
After a PREPARE, the transaction can be committed.
"""
if not self._parent.is_active:
raise exc.InvalidRequestError("This transaction is inactive")
self.connection._prepare_twophase_impl(self.xid)
self._is_prepared = True
def _do_rollback(self):
self.connection._rollback_twophase_impl(self.xid, self._is_prepared)
def _do_commit(self):
self.connection._commit_twophase_impl(self.xid, self._is_prepared)
class Engine(Connectable, log.Identified):
"""
Connects a :class:`~sqlalchemy.pool.Pool` and
:class:`~sqlalchemy.engine.base.Dialect` together to provide a source
of database connectivity and behavior.
An :class:`.Engine` object is instantiated publically using the
:func:`~sqlalchemy.create_engine` function.
See also:
:ref:`engines_toplevel`
:ref:`connections_toplevel`
"""
_execution_options = util.immutabledict()
_has_events = False
_connection_cls = Connection
def __init__(self, pool, dialect, url,
logging_name=None, echo=None, proxy=None,
execution_options=None
):
self.pool = pool
self.url = url
self.dialect = dialect
if logging_name:
self.logging_name = logging_name
self.echo = echo
self.engine = self
log.instance_logger(self, echoflag=echo)
if proxy:
interfaces.ConnectionProxy._adapt_listener(self, proxy)
if execution_options:
if 'isolation_level' in execution_options:
raise exc.ArgumentError(
"'isolation_level' execution option may "
"only be specified on Connection.execution_options(). "
"To set engine-wide isolation level, "
"use the isolation_level argument to create_engine()."
)
self.update_execution_options(**execution_options)
dispatch = event.dispatcher(events.ConnectionEvents)
def update_execution_options(self, **opt):
"""Update the default execution_options dictionary
of this :class:`.Engine`.
The given keys/values in \**opt are added to the
default execution options that will be used for
all connections. The initial contents of this dictionary
can be sent via the ``execution_options`` paramter
to :func:`.create_engine`.
See :meth:`.Connection.execution_options` for more
details on execution options.
"""
self._execution_options = \
self._execution_options.union(opt)
@property
def name(self):
"""String name of the :class:`~sqlalchemy.engine.Dialect` in use by
this ``Engine``."""
return self.dialect.name
@property
def driver(self):
"""Driver name of the :class:`~sqlalchemy.engine.Dialect` in use by
this ``Engine``."""
return self.dialect.driver
echo = log.echo_property()
def __repr__(self):
return 'Engine(%s)' % str(self.url)
def dispose(self):
"""Dispose of the connection pool used by this :class:`.Engine`.
A new connection pool is created immediately after the old one has
been disposed. This new pool, like all SQLAlchemy connection pools,
does not make any actual connections to the database until one is
first requested.
This method has two general use cases:
* When a dropped connection is detected, it is assumed that all
connections held by the pool are potentially dropped, and
the entire pool is replaced.
* An application may want to use :meth:`dispose` within a test
suite that is creating multiple engines.
It is critical to note that :meth:`dispose` does **not** guarantee
that the application will release all open database connections - only
those connections that are checked into the pool are closed.
Connections which remain checked out or have been detached from
the engine are not affected.
"""
self.pool.dispose()
self.pool = self.pool.recreate()
@util.deprecated("0.7", "Use the create() method on the given schema "
"object directly, i.e. :meth:`.Table.create`, "
":meth:`.Index.create`, :meth:`.MetaData.create_all`")
def create(self, entity, connection=None, **kwargs):
"""Emit CREATE statements for the given schema entity."""
from sqlalchemy.engine import ddl
self._run_visitor(ddl.SchemaGenerator, entity,
connection=connection, **kwargs)
@util.deprecated("0.7", "Use the drop() method on the given schema "
"object directly, i.e. :meth:`.Table.drop`, "
":meth:`.Index.drop`, :meth:`.MetaData.drop_all`")
def drop(self, entity, connection=None, **kwargs):
"""Emit DROP statements for the given schema entity."""
from sqlalchemy.engine import ddl
self._run_visitor(ddl.SchemaDropper, entity,
connection=connection, **kwargs)
def _execute_default(self, default):
connection = self.contextual_connect()
try:
return connection._execute_default(default, (), {})
finally:
connection.close()
@property
@util.deprecated("0.7",
"Use :attr:`~sqlalchemy.sql.expression.func` to create function constructs.")
def func(self):
return expression._FunctionGenerator(bind=self)
@util.deprecated("0.7",
"Use :func:`.expression.text` to create text constructs.")
def text(self, text, *args, **kwargs):
"""Return a :func:`~sqlalchemy.sql.expression.text` construct,
bound to this engine.
This is equivalent to::
text("SELECT * FROM table", bind=engine)
"""
return expression.text(text, bind=self, *args, **kwargs)
def _run_visitor(self, visitorcallable, element,
connection=None, **kwargs):
if connection is None:
conn = self.contextual_connect(close_with_result=False)
else:
conn = connection
try:
conn._run_visitor(visitorcallable, element, **kwargs)
finally:
if connection is None:
conn.close()
class _trans_ctx(object):
def __init__(self, conn, transaction, close_with_result):
self.conn = conn
self.transaction = transaction
self.close_with_result = close_with_result
def __enter__(self):
return self.conn
def __exit__(self, type, value, traceback):
if type is not None:
self.transaction.rollback()
else:
self.transaction.commit()
if not self.close_with_result:
self.conn.close()
def begin(self, close_with_result=False):
"""Return a context manager delivering a :class:`.Connection`
with a :class:`.Transaction` established.
E.g.::
with engine.begin() as conn:
conn.execute("insert into table (x, y, z) values (1, 2, 3)")
conn.execute("my_special_procedure(5)")
Upon successful operation, the :class:`.Transaction`
is committed. If an error is raised, the :class:`.Transaction`
is rolled back.
The ``close_with_result`` flag is normally ``False``, and indicates
that the :class:`.Connection` will be closed when the operation
is complete. When set to ``True``, it indicates the :class:`.Connection`
is in "single use" mode, where the :class:`.ResultProxy`
returned by the first call to :meth:`.Connection.execute` will
close the :class:`.Connection` when that :class:`.ResultProxy`
has exhausted all result rows.
New in 0.7.6.
See also:
:meth:`.Engine.connect` - procure a :class:`.Connection` from
an :class:`.Engine`.
:meth:`.Connection.begin` - start a :class:`.Transaction`
for a particular :class:`.Connection`.
"""
conn = self.contextual_connect(close_with_result=close_with_result)
trans = conn.begin()
return Engine._trans_ctx(conn, trans, close_with_result)
def transaction(self, callable_, *args, **kwargs):
"""Execute the given function within a transaction boundary.
The function is passed a :class:`.Connection` newly procured
from :meth:`.Engine.contextual_connect` as the first argument,
followed by the given \*args and \**kwargs.
e.g.::
def do_something(conn, x, y):
conn.execute("some statement", {'x':x, 'y':y})
engine.transaction(do_something, 5, 10)
The operations inside the function are all invoked within the
context of a single :class:`.Transaction`.
Upon success, the transaction is committed. If an
exception is raised, the transaction is rolled back
before propagating the exception.
.. note::
The :meth:`.transaction` method is superseded by
the usage of the Python ``with:`` statement, which can
be used with :meth:`.Engine.begin`::
with engine.begin() as conn:
conn.execute("some statement", {'x':5, 'y':10})
See also:
:meth:`.Engine.begin` - engine-level transactional
context
:meth:`.Connection.transaction` - connection-level version of
:meth:`.Engine.transaction`
"""
conn = self.contextual_connect()
try:
return conn.transaction(callable_, *args, **kwargs)
finally:
conn.close()
def run_callable(self, callable_, *args, **kwargs):
"""Given a callable object or function, execute it, passing
a :class:`.Connection` as the first argument.
The given \*args and \**kwargs are passed subsequent
to the :class:`.Connection` argument.
This function, along with :meth:`.Connection.run_callable`,
allows a function to be run with a :class:`.Connection`
or :class:`.Engine` object without the need to know
which one is being dealt with.
"""
conn = self.contextual_connect()
try:
return conn.run_callable(callable_, *args, **kwargs)
finally:
conn.close()
def execute(self, statement, *multiparams, **params):
"""Executes the given construct and returns a :class:`.ResultProxy`.
The arguments are the same as those used by
:meth:`.Connection.execute`.
Here, a :class:`.Connection` is acquired using the
:meth:`~.Engine.contextual_connect` method, and the statement executed
with that connection. The returned :class:`.ResultProxy` is flagged
such that when the :class:`.ResultProxy` is exhausted and its
underlying cursor is closed, the :class:`.Connection` created here
will also be closed, which allows its associated DBAPI connection
resource to be returned to the connection pool.
"""
connection = self.contextual_connect(close_with_result=True)
return connection.execute(statement, *multiparams, **params)
def scalar(self, statement, *multiparams, **params):
return self.execute(statement, *multiparams, **params).scalar()
def _execute_clauseelement(self, elem, multiparams=None, params=None):
connection = self.contextual_connect(close_with_result=True)
return connection._execute_clauseelement(elem, multiparams, params)
def _execute_compiled(self, compiled, multiparams, params):
connection = self.contextual_connect(close_with_result=True)
return connection._execute_compiled(compiled, multiparams, params)
def connect(self, **kwargs):
"""Return a new :class:`.Connection` object.
The :class:`.Connection` object is a facade that uses a DBAPI connection internally
in order to communicate with the database. This connection is procured
from the connection-holding :class:`.Pool` referenced by this :class:`.Engine`.
When the :meth:`~.Connection.close` method of the :class:`.Connection` object is called,
the underlying DBAPI connection is then returned to the connection pool,
where it may be used again in a subsequent call to :meth:`~.Engine.connect`.
"""
return self._connection_cls(self, **kwargs)
def contextual_connect(self, close_with_result=False, **kwargs):
"""Return a :class:`.Connection` object which may be part of some ongoing context.
By default, this method does the same thing as :meth:`.Engine.connect`.
Subclasses of :class:`.Engine` may override this method
to provide contextual behavior.
:param close_with_result: When True, the first :class:`.ResultProxy` created
by the :class:`.Connection` will call the :meth:`.Connection.close` method
of that connection as soon as any pending result rows are exhausted.
This is used to supply the "connectionless execution" behavior provided
by the :meth:`.Engine.execute` method.
"""
return self._connection_cls(self,
self.pool.connect(),
close_with_result=close_with_result,
**kwargs)
def table_names(self, schema=None, connection=None):
"""Return a list of all table names available in the database.
:param schema: Optional, retrieve names from a non-default schema.
:param connection: Optional, use a specified connection. Default is
the ``contextual_connect`` for this ``Engine``.
"""
if connection is None:
conn = self.contextual_connect()
else:
conn = connection
if not schema:
schema = self.dialect.default_schema_name
try:
return self.dialect.get_table_names(conn, schema)
finally:
if connection is None:
conn.close()
@util.deprecated("0.7", "Use autoload=True with :class:`.Table`, "
"or use the :class:`.Inspector` object.")
def reflecttable(self, table, connection=None, include_columns=None):
"""Load table description from the database.
Uses the given :class:`.Connection`, or if None produces
its own :class:`.Connection`, and passes the ``table``
and ``include_columns`` arguments onto that
:class:`.Connection` object's :meth:`.Connection.reflecttable`
method. The :class:`.Table` object is then populated
with new attributes.
"""
if connection is None:
conn = self.contextual_connect()
else:
conn = connection
try:
self.dialect.reflecttable(conn, table, include_columns)
finally:
if connection is None:
conn.close()
def has_table(self, table_name, schema=None):
return self.run_callable(self.dialect.has_table, table_name, schema)
def raw_connection(self):
"""Return a "raw" DBAPI connection from the connection pool.
The returned object is a proxied version of the DBAPI
connection object used by the underlying driver in use.
The object will have all the same behavior as the real DBAPI
connection, except that its ``close()`` method will result in the
connection being returned to the pool, rather than being closed
for real.
This method provides direct DBAPI connection access for
special situations. In most situations, the :class:`.Connection`
object should be used, which is procured using the
:meth:`.Engine.connect` method.
"""
return self.pool.unique_connection()
# This reconstructor is necessary so that pickles with the C extension or
# without use the same Binary format.
try:
# We need a different reconstructor on the C extension so that we can
# add extra checks that fields have correctly been initialized by
# __setstate__.
from sqlalchemy.cresultproxy import safe_rowproxy_reconstructor
# The extra function embedding is needed so that the
# reconstructor function has the same signature whether or not
# the extension is present.
def rowproxy_reconstructor(cls, state):
return safe_rowproxy_reconstructor(cls, state)
except ImportError:
def rowproxy_reconstructor(cls, state):
obj = cls.__new__(cls)
obj.__setstate__(state)
return obj
try:
from sqlalchemy.cresultproxy import BaseRowProxy
except ImportError:
class BaseRowProxy(object):
__slots__ = ('_parent', '_row', '_processors', '_keymap')
def __init__(self, parent, row, processors, keymap):
"""RowProxy objects are constructed by ResultProxy objects."""
self._parent = parent
self._row = row
self._processors = processors
self._keymap = keymap
def __reduce__(self):
return (rowproxy_reconstructor,
(self.__class__, self.__getstate__()))
def values(self):
"""Return the values represented by this RowProxy as a list."""
return list(self)
def __iter__(self):
for processor, value in izip(self._processors, self._row):
if processor is None:
yield value
else:
yield processor(value)
def __len__(self):
return len(self._row)
def __getitem__(self, key):
try:
processor, obj, index = self._keymap[key]
except KeyError:
processor, obj, index = self._parent._key_fallback(key)
except TypeError:
if isinstance(key, slice):
l = []
for processor, value in izip(self._processors[key],
self._row[key]):
if processor is None:
l.append(value)
else:
l.append(processor(value))
return tuple(l)
else:
raise
if index is None:
raise exc.InvalidRequestError(
"Ambiguous column name '%s' in result set! "
"try 'use_labels' option on select statement." % key)
if processor is not None:
return processor(self._row[index])
else:
return self._row[index]
def __getattr__(self, name):
try:
return self[name]
except KeyError, e:
raise AttributeError(e.args[0])
class RowProxy(BaseRowProxy):
"""Proxy values from a single cursor row.
Mostly follows "ordered dictionary" behavior, mapping result
values to the string-based column name, the integer position of
the result in the row, as well as Column instances which can be
mapped to the original Columns that produced this result set (for
results that correspond to constructed SQL expressions).
"""
__slots__ = ()
def __contains__(self, key):
return self._parent._has_key(self._row, key)
def __getstate__(self):
return {
'_parent': self._parent,
'_row': tuple(self)
}
def __setstate__(self, state):
self._parent = parent = state['_parent']
self._row = state['_row']
self._processors = parent._processors
self._keymap = parent._keymap
__hash__ = None
def __eq__(self, other):
return other is self or other == tuple(self)
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return repr(tuple(self))
def has_key(self, key):
"""Return True if this RowProxy contains the given key."""
return self._parent._has_key(self._row, key)
def items(self):
"""Return a list of tuples, each tuple containing a key/value pair."""
# TODO: no coverage here
return [(key, self[key]) for key in self.iterkeys()]
def keys(self):
"""Return the list of keys as strings represented by this RowProxy."""
return self._parent.keys
def iterkeys(self):
return iter(self._parent.keys)
def itervalues(self):
return iter(self)
try:
# Register RowProxy with Sequence,
# so sequence protocol is implemented
from collections import Sequence
Sequence.register(RowProxy)
except ImportError:
pass
class ResultMetaData(object):
"""Handle cursor.description, applying additional info from an execution
context."""
def __init__(self, parent, metadata):
self._processors = processors = []
# We do not strictly need to store the processor in the key mapping,
# though it is faster in the Python version (probably because of the
# saved attribute lookup self._processors)
self._keymap = keymap = {}
self.keys = []
context = parent.context
dialect = context.dialect
typemap = dialect.dbapi_type_map
translate_colname = dialect._translate_colname
# high precedence key values.
primary_keymap = {}
for i, rec in enumerate(metadata):
colname = rec[0]
coltype = rec[1]
if dialect.description_encoding:
colname = dialect._description_decoder(colname)
if translate_colname:
colname, untranslated = translate_colname(colname)
if context.result_map:
try:
name, obj, type_ = context.result_map[colname.lower()]
except KeyError:
name, obj, type_ = \
colname, None, typemap.get(coltype, types.NULLTYPE)
else:
name, obj, type_ = \
colname, None, typemap.get(coltype, types.NULLTYPE)
processor = type_._cached_result_processor(dialect, coltype)
processors.append(processor)
rec = (processor, obj, i)
# indexes as keys. This is only needed for the Python version of
# RowProxy (the C version uses a faster path for integer indexes).
primary_keymap[i] = rec
# populate primary keymap, looking for conflicts.
if primary_keymap.setdefault(name.lower(), rec) is not rec:
# place a record that doesn't have the "index" - this
# is interpreted later as an AmbiguousColumnError,
# but only when actually accessed. Columns
# colliding by name is not a problem if those names
# aren't used; integer and ColumnElement access is always
# unambiguous.
primary_keymap[name.lower()] = (processor, obj, None)
if dialect.requires_name_normalize:
colname = dialect.normalize_name(colname)
self.keys.append(colname)
if obj:
for o in obj:
keymap[o] = rec
if translate_colname and \
untranslated:
keymap[untranslated] = rec
# overwrite keymap values with those of the
# high precedence keymap.
keymap.update(primary_keymap)
if parent._echo:
context.engine.logger.debug(
"Col %r", tuple(x[0] for x in metadata))
@util.pending_deprecation("0.8", "sqlite dialect uses "
"_translate_colname() now")
def _set_keymap_synonym(self, name, origname):
"""Set a synonym for the given name.
Some dialects (SQLite at the moment) may use this to
adjust the column names that are significant within a
row.
"""
rec = (processor, obj, i) = self._keymap[origname.lower()]
if self._keymap.setdefault(name, rec) is not rec:
self._keymap[name] = (processor, obj, None)
def _key_fallback(self, key, raiseerr=True):
map = self._keymap
result = None
if isinstance(key, basestring):
result = map.get(key.lower())
# fallback for targeting a ColumnElement to a textual expression
# this is a rare use case which only occurs when matching text()
# or colummn('name') constructs to ColumnElements, or after a
# pickle/unpickle roundtrip
elif isinstance(key, expression.ColumnElement):
if key._label and key._label.lower() in map:
result = map[key._label.lower()]
elif hasattr(key, 'name') and key.name.lower() in map:
# match is only on name.
result = map[key.name.lower()]
# search extra hard to make sure this
# isn't a column/label name overlap.
# this check isn't currently available if the row
# was unpickled.
if result is not None and \
result[1] is not None:
for obj in result[1]:
if key._compare_name_for_result(obj):
break
else:
result = None
if result is None:
if raiseerr:
raise exc.NoSuchColumnError(
"Could not locate column in row for column '%s'" %
expression._string_or_unprintable(key))
else:
return None
else:
map[key] = result
return result
def _has_key(self, row, key):
if key in self._keymap:
return True
else:
return self._key_fallback(key, False) is not None
def __getstate__(self):
return {
'_pickled_keymap': dict(
(key, index)
for key, (processor, obj, index) in self._keymap.iteritems()
if isinstance(key, (basestring, int))
),
'keys': self.keys
}
def __setstate__(self, state):
# the row has been processed at pickling time so we don't need any
# processor anymore
self._processors = [None for _ in xrange(len(state['keys']))]
self._keymap = keymap = {}
for key, index in state['_pickled_keymap'].iteritems():
# not preserving "obj" here, unfortunately our
# proxy comparison fails with the unpickle
keymap[key] = (None, None, index)
self.keys = state['keys']
self._echo = False
class ResultProxy(object):
"""Wraps a DB-API cursor object to provide easier access to row columns.
Individual columns may be accessed by their integer position,
case-insensitive column name, or by ``schema.Column``
object. e.g.::
row = fetchone()
col1 = row[0] # access via integer position
col2 = row['col2'] # access via name
col3 = row[mytable.c.mycol] # access via Column object.
``ResultProxy`` also handles post-processing of result column
data using ``TypeEngine`` objects, which are referenced from
the originating SQL statement that produced this result set.
"""
_process_row = RowProxy
out_parameters = None
_can_close_connection = False
def __init__(self, context):
self.context = context
self.dialect = context.dialect
self.closed = False
self.cursor = self._saved_cursor = context.cursor
self.connection = context.root_connection
self._echo = self.connection._echo and \
context.engine._should_log_debug()
self._init_metadata()
def _init_metadata(self):
metadata = self._cursor_description()
if metadata is None:
self._metadata = None
else:
self._metadata = ResultMetaData(self, metadata)
def keys(self):
"""Return the current set of string keys for rows."""
if self._metadata:
return self._metadata.keys
else:
return []
@util.memoized_property
def rowcount(self):
"""Return the 'rowcount' for this result.
The 'rowcount' reports the number of rows affected
by an UPDATE or DELETE statement. It has *no* other
uses and is not intended to provide the number of rows
present from a SELECT.
Note that this row count may not be properly implemented in some
dialects; this is indicated by
:meth:`~sqlalchemy.engine.base.ResultProxy.supports_sane_rowcount()`
and
:meth:`~sqlalchemy.engine.base.ResultProxy.supports_sane_multi_rowcount()`.
``rowcount()`` also may not work at this time for a statement that
uses ``returning()``.
"""
try:
return self.context.rowcount
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None, self.cursor, self.context)
raise
@property
def lastrowid(self):
"""return the 'lastrowid' accessor on the DBAPI cursor.
This is a DBAPI specific method and is only functional
for those backends which support it, for statements
where it is appropriate. It's behavior is not
consistent across backends.
Usage of this method is normally unnecessary; the
:attr:`~ResultProxy.inserted_primary_key` attribute provides a
tuple of primary key values for a newly inserted row,
regardless of database backend.
"""
try:
return self._saved_cursor.lastrowid
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self._saved_cursor, self.context)
raise
@property
def returns_rows(self):
"""True if this :class:`.ResultProxy` returns rows.
I.e. if it is legal to call the methods
:meth:`~.ResultProxy.fetchone`,
:meth:`~.ResultProxy.fetchmany`
:meth:`~.ResultProxy.fetchall`.
"""
return self._metadata is not None
@property
def is_insert(self):
"""True if this :class:`.ResultProxy` is the result
of a executing an expression language compiled
:func:`.expression.insert` construct.
When True, this implies that the
:attr:`inserted_primary_key` attribute is accessible,
assuming the statement did not include
a user defined "returning" construct.
"""
return self.context.isinsert
def _cursor_description(self):
"""May be overridden by subclasses."""
return self._saved_cursor.description
def close(self, _autoclose_connection=True):
"""Close this ResultProxy.
Closes the underlying DBAPI cursor corresponding to the execution.
Note that any data cached within this ResultProxy is still available.
For some types of results, this may include buffered rows.
If this ResultProxy was generated from an implicit execution,
the underlying Connection will also be closed (returns the
underlying DBAPI connection to the connection pool.)
This method is called automatically when:
* all result rows are exhausted using the fetchXXX() methods.
* cursor.description is None.
"""
if not self.closed:
self.closed = True
self.connection._safe_close_cursor(self.cursor)
if _autoclose_connection and \
self.connection.should_close_with_result:
self.connection.close()
# allow consistent errors
self.cursor = None
def __iter__(self):
while True:
row = self.fetchone()
if row is None:
raise StopIteration
else:
yield row
@util.memoized_property
def inserted_primary_key(self):
"""Return the primary key for the row just inserted.
The return value is a list of scalar values
corresponding to the list of primary key columns
in the target table.
This only applies to single row :func:`.insert`
constructs which did not explicitly specify
:meth:`.Insert.returning`.
Note that primary key columns which specify a
server_default clause,
or otherwise do not qualify as "autoincrement"
columns (see the notes at :class:`.Column`), and were
generated using the database-side default, will
appear in this list as ``None`` unless the backend
supports "returning" and the insert statement executed
with the "implicit returning" enabled.
"""
if not self.context.isinsert:
raise exc.InvalidRequestError(
"Statement is not an insert() expression construct.")
elif self.context._is_explicit_returning:
raise exc.InvalidRequestError(
"Can't call inserted_primary_key when returning() "
"is used.")
return self.context.inserted_primary_key
@util.deprecated("0.6", "Use :attr:`.ResultProxy.inserted_primary_key`")
def last_inserted_ids(self):
"""Return the primary key for the row just inserted."""
return self.inserted_primary_key
def last_updated_params(self):
"""Return the collection of updated parameters from this
execution.
"""
if self.context.executemany:
return self.context.compiled_parameters
else:
return self.context.compiled_parameters[0]
def last_inserted_params(self):
"""Return the collection of inserted parameters from this
execution.
"""
if self.context.executemany:
return self.context.compiled_parameters
else:
return self.context.compiled_parameters[0]
def lastrow_has_defaults(self):
"""Return ``lastrow_has_defaults()`` from the underlying
ExecutionContext.
See ExecutionContext for details.
"""
return self.context.lastrow_has_defaults()
def postfetch_cols(self):
"""Return ``postfetch_cols()`` from the underlying ExecutionContext.
See ExecutionContext for details.
"""
return self.context.postfetch_cols
def prefetch_cols(self):
return self.context.prefetch_cols
def supports_sane_rowcount(self):
"""Return ``supports_sane_rowcount`` from the dialect."""
return self.dialect.supports_sane_rowcount
def supports_sane_multi_rowcount(self):
"""Return ``supports_sane_multi_rowcount`` from the dialect."""
return self.dialect.supports_sane_multi_rowcount
def _fetchone_impl(self):
try:
return self.cursor.fetchone()
except AttributeError:
self._non_result()
def _fetchmany_impl(self, size=None):
try:
if size is None:
return self.cursor.fetchmany()
else:
return self.cursor.fetchmany(size)
except AttributeError:
self._non_result()
def _fetchall_impl(self):
try:
return self.cursor.fetchall()
except AttributeError:
self._non_result()
def _non_result(self):
if self._metadata is None:
raise exc.ResourceClosedError(
"This result object does not return rows. "
"It has been closed automatically.",
)
else:
raise exc.ResourceClosedError("This result object is closed.")
def process_rows(self, rows):
process_row = self._process_row
metadata = self._metadata
keymap = metadata._keymap
processors = metadata._processors
if self._echo:
log = self.context.engine.logger.debug
l = []
for row in rows:
log("Row %r", row)
l.append(process_row(metadata, row, processors, keymap))
return l
else:
return [process_row(metadata, row, processors, keymap)
for row in rows]
def fetchall(self):
"""Fetch all rows, just like DB-API ``cursor.fetchall()``."""
try:
l = self.process_rows(self._fetchall_impl())
self.close()
return l
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
def fetchmany(self, size=None):
"""Fetch many rows, just like DB-API
``cursor.fetchmany(size=cursor.arraysize)``.
If rows are present, the cursor remains open after this is called.
Else the cursor is automatically closed and an empty list is returned.
"""
try:
l = self.process_rows(self._fetchmany_impl(size))
if len(l) == 0:
self.close()
return l
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
def fetchone(self):
"""Fetch one row, just like DB-API ``cursor.fetchone()``.
If a row is present, the cursor remains open after this is called.
Else the cursor is automatically closed and None is returned.
"""
try:
row = self._fetchone_impl()
if row is not None:
return self.process_rows([row])[0]
else:
self.close()
return None
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
def first(self):
"""Fetch the first row and then close the result set unconditionally.
Returns None if no row is present.
"""
if self._metadata is None:
self._non_result()
try:
row = self._fetchone_impl()
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
try:
if row is not None:
return self.process_rows([row])[0]
else:
return None
finally:
self.close()
def scalar(self):
"""Fetch the first column of the first row, and close the result set.
Returns None if no row is present.
"""
row = self.first()
if row is not None:
return row[0]
else:
return None
class BufferedRowResultProxy(ResultProxy):
"""A ResultProxy with row buffering behavior.
``ResultProxy`` that buffers the contents of a selection of rows
before ``fetchone()`` is called. This is to allow the results of
``cursor.description`` to be available immediately, when
interfacing with a DB-API that requires rows to be consumed before
this information is available (currently psycopg2, when used with
server-side cursors).
The pre-fetching behavior fetches only one row initially, and then
grows its buffer size by a fixed amount with each successive need
for additional rows up to a size of 100.
"""
def _init_metadata(self):
self.__buffer_rows()
super(BufferedRowResultProxy, self)._init_metadata()
# this is a "growth chart" for the buffering of rows.
# each successive __buffer_rows call will use the next
# value in the list for the buffer size until the max
# is reached
size_growth = {
1 : 5,
5 : 10,
10 : 20,
20 : 50,
50 : 100,
100 : 250,
250 : 500,
500 : 1000
}
def __buffer_rows(self):
size = getattr(self, '_bufsize', 1)
self.__rowbuffer = collections.deque(self.cursor.fetchmany(size))
self._bufsize = self.size_growth.get(size, size)
def _fetchone_impl(self):
if self.closed:
return None
if not self.__rowbuffer:
self.__buffer_rows()
if not self.__rowbuffer:
return None
return self.__rowbuffer.popleft()
def _fetchmany_impl(self, size=None):
if size is None:
return self._fetchall_impl()
result = []
for x in range(0, size):
row = self._fetchone_impl()
if row is None:
break
result.append(row)
return result
def _fetchall_impl(self):
self.__rowbuffer.extend(self.cursor.fetchall())
ret = self.__rowbuffer
self.__rowbuffer = collections.deque()
return ret
class FullyBufferedResultProxy(ResultProxy):
"""A result proxy that buffers rows fully upon creation.
Used for operations where a result is to be delivered
after the database conversation can not be continued,
such as MSSQL INSERT...OUTPUT after an autocommit.
"""
def _init_metadata(self):
super(FullyBufferedResultProxy, self)._init_metadata()
self.__rowbuffer = self._buffer_rows()
def _buffer_rows(self):
return collections.deque(self.cursor.fetchall())
def _fetchone_impl(self):
if self.__rowbuffer:
return self.__rowbuffer.popleft()
else:
return None
def _fetchmany_impl(self, size=None):
if size is None:
return self._fetchall_impl()
result = []
for x in range(0, size):
row = self._fetchone_impl()
if row is None:
break
result.append(row)
return result
def _fetchall_impl(self):
ret = self.__rowbuffer
self.__rowbuffer = collections.deque()
return ret
class BufferedColumnRow(RowProxy):
def __init__(self, parent, row, processors, keymap):
# preprocess row
row = list(row)
# this is a tad faster than using enumerate
index = 0
for processor in parent._orig_processors:
if processor is not None:
row[index] = processor(row[index])
index += 1
row = tuple(row)
super(BufferedColumnRow, self).__init__(parent, row,
processors, keymap)
class BufferedColumnResultProxy(ResultProxy):
"""A ResultProxy with column buffering behavior.
``ResultProxy`` that loads all columns into memory each time
fetchone() is called. If fetchmany() or fetchall() are called,
the full grid of results is fetched. This is to operate with
databases where result rows contain "live" results that fall out
of scope unless explicitly fetched. Currently this includes
cx_Oracle LOB objects.
"""
_process_row = BufferedColumnRow
def _init_metadata(self):
super(BufferedColumnResultProxy, self)._init_metadata()
metadata = self._metadata
# orig_processors will be used to preprocess each row when they are
# constructed.
metadata._orig_processors = metadata._processors
# replace the all type processors by None processors.
metadata._processors = [None for _ in xrange(len(metadata.keys))]
keymap = {}
for k, (func, obj, index) in metadata._keymap.iteritems():
keymap[k] = (None, obj, index)
self._metadata._keymap = keymap
def fetchall(self):
# can't call cursor.fetchall(), since rows must be
# fully processed before requesting more from the DBAPI.
l = []
while True:
row = self.fetchone()
if row is None:
break
l.append(row)
return l
def fetchmany(self, size=None):
# can't call cursor.fetchmany(), since rows must be
# fully processed before requesting more from the DBAPI.
if size is None:
return self.fetchall()
l = []
for i in xrange(size):
row = self.fetchone()
if row is None:
break
l.append(row)
return l
def connection_memoize(key):
"""Decorator, memoize a function in a connection.info stash.
Only applicable to functions which take no arguments other than a
connection. The memo will be stored in ``connection.info[key]``.
"""
@util.decorator
def decorated(fn, self, connection):
connection = connection.connect()
try:
return connection.info[key]
except KeyError:
connection.info[key] = val = fn(self, connection)
return val
return decorated