2235 lines
81 KiB
Python
2235 lines
81 KiB
Python
# engine/base.py
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# Copyright (C) 2005-2018 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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from __future__ import with_statement
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"""Defines :class:`.Connection` and :class:`.Engine`.
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"""
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import sys
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from .. import exc, util, log, interfaces
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from ..sql import util as sql_util
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from ..sql import schema
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from .interfaces import Connectable, ExceptionContext
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from .util import _distill_params
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import contextlib
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class Connection(Connectable):
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"""Provides high-level functionality for a wrapped DB-API connection.
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Provides execution support for string-based SQL statements as well as
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:class:`.ClauseElement`, :class:`.Compiled` and :class:`.DefaultGenerator`
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objects. Provides a :meth:`begin` method to return :class:`.Transaction`
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objects.
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The Connection object is **not** thread-safe. While a Connection can be
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shared among threads using properly synchronized access, it is still
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possible that the underlying DBAPI connection may not support shared
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access between threads. Check the DBAPI documentation for details.
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The Connection object represents a single dbapi connection checked out
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from the connection pool. In this state, the connection pool has no affect
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upon the connection, including its expiration or timeout state. For the
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connection pool to properly manage connections, connections should be
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returned to the connection pool (i.e. ``connection.close()``) whenever the
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connection is not in use.
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.. index::
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single: thread safety; Connection
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"""
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schema_for_object = schema._schema_getter(None)
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"""Return the ".schema" attribute for an object.
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Used for :class:`.Table`, :class:`.Sequence` and similar objects,
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and takes into account
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the :paramref:`.Connection.execution_options.schema_translate_map`
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parameter.
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.. versionadded:: 1.1
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.. seealso::
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:ref:`schema_translating`
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"""
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def __init__(self, engine, connection=None, close_with_result=False,
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_branch_from=None, _execution_options=None,
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_dispatch=None,
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_has_events=None):
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"""Construct a new Connection.
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The constructor here is not public and is only called only by an
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:class:`.Engine`. See :meth:`.Engine.connect` and
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:meth:`.Engine.contextual_connect` methods.
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"""
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self.engine = engine
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self.dialect = engine.dialect
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self.__branch_from = _branch_from
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self.__branch = _branch_from is not None
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if _branch_from:
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self.__connection = connection
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self._execution_options = _execution_options
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self._echo = _branch_from._echo
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self.should_close_with_result = False
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self.dispatch = _dispatch
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self._has_events = _branch_from._has_events
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self.schema_for_object = _branch_from.schema_for_object
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else:
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self.__connection = connection \
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if connection is not None else engine.raw_connection()
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self.__transaction = None
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self.__savepoint_seq = 0
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self.should_close_with_result = close_with_result
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self.__invalid = False
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self.__can_reconnect = True
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self._echo = self.engine._should_log_info()
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if _has_events is None:
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# if _has_events is sent explicitly as False,
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# then don't join the dispatch of the engine; we don't
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# want to handle any of the engine's events in that case.
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self.dispatch = self.dispatch._join(engine.dispatch)
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self._has_events = _has_events or (
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_has_events is None and engine._has_events)
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assert not _execution_options
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self._execution_options = engine._execution_options
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if self._has_events or self.engine._has_events:
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self.dispatch.engine_connect(self, self.__branch)
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def _branch(self):
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"""Return a new Connection which references this Connection's
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engine and connection; but does not have close_with_result enabled,
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and also whose close() method does nothing.
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The Core uses this very sparingly, only in the case of
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custom SQL default functions that are to be INSERTed as the
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primary key of a row where we need to get the value back, so we have
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to invoke it distinctly - this is a very uncommon case.
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Userland code accesses _branch() when the connect() or
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contextual_connect() methods are called. The branched connection
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acts as much as possible like the parent, except that it stays
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connected when a close() event occurs.
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"""
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if self.__branch_from:
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return self.__branch_from._branch()
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else:
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return self.engine._connection_cls(
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self.engine,
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self.__connection,
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_branch_from=self,
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_execution_options=self._execution_options,
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_has_events=self._has_events,
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_dispatch=self.dispatch)
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@property
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def _root(self):
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"""return the 'root' connection.
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Returns 'self' if this connection is not a branch, else
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returns the root connection from which we ultimately branched.
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"""
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if self.__branch_from:
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return self.__branch_from
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else:
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return self
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def _clone(self):
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"""Create a shallow copy of this Connection.
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"""
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c = self.__class__.__new__(self.__class__)
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c.__dict__ = self.__dict__.copy()
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return c
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def __enter__(self):
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return self
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def __exit__(self, type, value, traceback):
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self.close()
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def execution_options(self, **opt):
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r""" Set non-SQL options for the connection which take effect
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during execution.
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The method returns a copy of this :class:`.Connection` which references
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the same underlying DBAPI connection, but also defines the given
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execution options which will take effect for a call to
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:meth:`execute`. As the new :class:`.Connection` references the same
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underlying resource, it's usually a good idea to ensure that the copies
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will be discarded immediately, which is implicit if used as in::
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result = connection.execution_options(stream_results=True).\
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execute(stmt)
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Note that any key/value can be passed to
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:meth:`.Connection.execution_options`, and it will be stored in the
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``_execution_options`` dictionary of the :class:`.Connection`. It
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is suitable for usage by end-user schemes to communicate with
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event listeners, for example.
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The keywords that are currently recognized by SQLAlchemy itself
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include all those listed under :meth:`.Executable.execution_options`,
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as well as others that are specific to :class:`.Connection`.
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:param autocommit: Available on: Connection, statement.
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When True, a COMMIT will be invoked after execution
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when executed in 'autocommit' mode, i.e. when an explicit
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transaction is not begun on the connection. Note that DBAPI
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connections by default are always in a transaction - SQLAlchemy uses
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rules applied to different kinds of statements to determine if
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COMMIT will be invoked in order to provide its "autocommit" feature.
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Typically, all INSERT/UPDATE/DELETE statements as well as
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CREATE/DROP statements have autocommit behavior enabled; SELECT
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constructs do not. Use this option when invoking a SELECT or other
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specific SQL construct where COMMIT is desired (typically when
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calling stored procedures and such), and an explicit
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transaction is not in progress.
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:param compiled_cache: Available on: Connection.
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A dictionary where :class:`.Compiled` objects
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will be cached when the :class:`.Connection` compiles a clause
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expression into a :class:`.Compiled` object.
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It is the user's responsibility to
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manage the size of this dictionary, which will have keys
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corresponding to the dialect, clause element, the column
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names within the VALUES or SET clause of an INSERT or UPDATE,
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as well as the "batch" mode for an INSERT or UPDATE statement.
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The format of this dictionary is not guaranteed to stay the
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same in future releases.
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Note that the ORM makes use of its own "compiled" caches for
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some operations, including flush operations. The caching
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used by the ORM internally supersedes a cache dictionary
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specified here.
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:param isolation_level: Available on: :class:`.Connection`.
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Set the transaction isolation level for
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the lifespan of this :class:`.Connection` object (*not* the
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underlying DBAPI connection, for which the level is reset
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to its original setting upon termination of this
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:class:`.Connection` object).
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Valid values include
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those string values accepted by the
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:paramref:`.create_engine.isolation_level`
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parameter passed to :func:`.create_engine`. These levels are
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semi-database specific; see individual dialect documentation for
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valid levels.
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Note that this option necessarily affects the underlying
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DBAPI connection for the lifespan of the originating
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:class:`.Connection`, and is not per-execution. This
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setting is not removed until the underlying DBAPI connection
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is returned to the connection pool, i.e.
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the :meth:`.Connection.close` method is called.
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.. warning:: The ``isolation_level`` execution option should
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**not** be used when a transaction is already established, that
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is, the :meth:`.Connection.begin` method or similar has been
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called. A database cannot change the isolation level on a
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transaction in progress, and different DBAPIs and/or
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SQLAlchemy dialects may implicitly roll back or commit
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the transaction, or not affect the connection at all.
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.. versionchanged:: 0.9.9 A warning is emitted when the
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``isolation_level`` execution option is used after a
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transaction has been started with :meth:`.Connection.begin`
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or similar.
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.. note:: The ``isolation_level`` execution option is implicitly
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reset if the :class:`.Connection` is invalidated, e.g. via
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the :meth:`.Connection.invalidate` method, or if a
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disconnection error occurs. The new connection produced after
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the invalidation will not have the isolation level re-applied
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to it automatically.
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.. seealso::
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:paramref:`.create_engine.isolation_level`
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- set per :class:`.Engine` isolation level
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:meth:`.Connection.get_isolation_level` - view current level
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:ref:`SQLite Transaction Isolation <sqlite_isolation_level>`
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:ref:`PostgreSQL Transaction Isolation <postgresql_isolation_level>`
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:ref:`MySQL Transaction Isolation <mysql_isolation_level>`
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:ref:`SQL Server Transaction Isolation <mssql_isolation_level>`
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:ref:`session_transaction_isolation` - for the ORM
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:param no_parameters: When ``True``, if the final parameter
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list or dictionary is totally empty, will invoke the
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statement on the cursor as ``cursor.execute(statement)``,
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not passing the parameter collection at all.
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Some DBAPIs such as psycopg2 and mysql-python consider
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percent signs as significant only when parameters are
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present; this option allows code to generate SQL
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containing percent signs (and possibly other characters)
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that is neutral regarding whether it's executed by the DBAPI
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or piped into a script that's later invoked by
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command line tools.
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.. versionadded:: 0.7.6
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:param stream_results: Available on: Connection, statement.
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Indicate to the dialect that results should be
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"streamed" and not pre-buffered, if possible. This is a limitation
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of many DBAPIs. The flag is currently understood only by the
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psycopg2, mysqldb and pymysql dialects.
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:param schema_translate_map: Available on: Connection, Engine.
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A dictionary mapping schema names to schema names, that will be
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applied to the :paramref:`.Table.schema` element of each
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:class:`.Table` encountered when SQL or DDL expression elements
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are compiled into strings; the resulting schema name will be
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converted based on presence in the map of the original name.
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.. versionadded:: 1.1
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.. seealso::
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:ref:`schema_translating`
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"""
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c = self._clone()
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c._execution_options = c._execution_options.union(opt)
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if self._has_events or self.engine._has_events:
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self.dispatch.set_connection_execution_options(c, opt)
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self.dialect.set_connection_execution_options(c, opt)
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return c
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@property
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def closed(self):
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"""Return True if this connection is closed."""
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return '_Connection__connection' not in self.__dict__ \
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and not self.__can_reconnect
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@property
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def invalidated(self):
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"""Return True if this connection was invalidated."""
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return self._root.__invalid
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@property
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def connection(self):
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"""The underlying DB-API connection managed by this Connection.
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.. seealso::
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:ref:`dbapi_connections`
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"""
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try:
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return self.__connection
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except AttributeError:
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# escape "except AttributeError" before revalidating
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# to prevent misleading stacktraces in Py3K
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pass
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try:
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return self._revalidate_connection()
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except BaseException as e:
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self._handle_dbapi_exception(e, None, None, None, None)
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def get_isolation_level(self):
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"""Return the current isolation level assigned to this
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:class:`.Connection`.
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This will typically be the default isolation level as determined
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by the dialect, unless if the
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:paramref:`.Connection.execution_options.isolation_level`
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feature has been used to alter the isolation level on a
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per-:class:`.Connection` basis.
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This attribute will typically perform a live SQL operation in order
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to procure the current isolation level, so the value returned is the
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actual level on the underlying DBAPI connection regardless of how
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this state was set. Compare to the
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:attr:`.Connection.default_isolation_level` accessor
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which returns the dialect-level setting without performing a SQL
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query.
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.. versionadded:: 0.9.9
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.. seealso::
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:attr:`.Connection.default_isolation_level` - view default level
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:paramref:`.create_engine.isolation_level`
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- set per :class:`.Engine` isolation level
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:paramref:`.Connection.execution_options.isolation_level`
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- set per :class:`.Connection` isolation level
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"""
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try:
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return self.dialect.get_isolation_level(self.connection)
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except BaseException as e:
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self._handle_dbapi_exception(e, None, None, None, None)
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@property
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def default_isolation_level(self):
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"""The default isolation level assigned to this :class:`.Connection`.
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This is the isolation level setting that the :class:`.Connection`
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has when first procured via the :meth:`.Engine.connect` method.
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This level stays in place until the
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:paramref:`.Connection.execution_options.isolation_level` is used
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to change the setting on a per-:class:`.Connection` basis.
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Unlike :meth:`.Connection.get_isolation_level`, this attribute is set
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ahead of time from the first connection procured by the dialect,
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so SQL query is not invoked when this accessor is called.
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.. versionadded:: 0.9.9
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.. seealso::
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:meth:`.Connection.get_isolation_level` - view current level
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:paramref:`.create_engine.isolation_level`
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- set per :class:`.Engine` isolation level
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:paramref:`.Connection.execution_options.isolation_level`
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- set per :class:`.Connection` isolation level
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"""
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return self.dialect.default_isolation_level
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def _revalidate_connection(self):
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if self.__branch_from:
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return self.__branch_from._revalidate_connection()
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if self.__can_reconnect and self.__invalid:
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if self.__transaction is not None:
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raise exc.InvalidRequestError(
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"Can't reconnect until invalid "
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"transaction is rolled back")
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self.__connection = self.engine.raw_connection(_connection=self)
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self.__invalid = False
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return self.__connection
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raise exc.ResourceClosedError("This Connection is closed")
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@property
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def _connection_is_valid(self):
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# use getattr() for is_valid to support exceptions raised in
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# dialect initializer, where the connection is not wrapped in
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# _ConnectionFairy
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return getattr(self.__connection, 'is_valid', False)
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@property
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def _still_open_and_connection_is_valid(self):
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return \
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not self.closed and \
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not self.invalidated and \
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getattr(self.__connection, 'is_valid', False)
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@property
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def info(self):
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"""Info dictionary associated with the underlying DBAPI connection
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referred to by this :class:`.Connection`, allowing user-defined
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data to be associated with the connection.
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The data here will follow along with the DBAPI connection including
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after it is returned to the connection pool and used again
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in subsequent instances of :class:`.Connection`.
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"""
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return self.connection.info
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def connect(self):
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"""Returns a branched version of this :class:`.Connection`.
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The :meth:`.Connection.close` method on the returned
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:class:`.Connection` can be called and this
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:class:`.Connection` will remain open.
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This method provides usage symmetry with
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:meth:`.Engine.connect`, including for usage
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with context managers.
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"""
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return self._branch()
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def contextual_connect(self, **kwargs):
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"""Returns a branched version of this :class:`.Connection`.
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The :meth:`.Connection.close` method on the returned
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:class:`.Connection` can be called and this
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:class:`.Connection` will remain open.
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This method provides usage symmetry with
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:meth:`.Engine.contextual_connect`, including for usage
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with context managers.
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"""
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return self._branch()
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def invalidate(self, exception=None):
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"""Invalidate the underlying DBAPI connection associated with
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this :class:`.Connection`.
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The underlying DBAPI connection is literally closed (if
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possible), and is discarded. Its source connection pool will
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typically lazily create a new connection to replace it.
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Upon the next use (where "use" typically means using the
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:meth:`.Connection.execute` method or similar),
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this :class:`.Connection` will attempt to
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procure a new DBAPI connection using the services of the
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:class:`.Pool` as a source of connectivity (e.g. a "reconnection").
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If a transaction was in progress (e.g. the
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:meth:`.Connection.begin` method has been called) when
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:meth:`.Connection.invalidate` method is called, at the DBAPI
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level all state associated with this transaction is lost, as
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the DBAPI connection is closed. The :class:`.Connection`
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will not allow a reconnection to proceed until the
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:class:`.Transaction` object is ended, by calling the
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:meth:`.Transaction.rollback` method; until that point, any attempt at
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continuing to use the :class:`.Connection` will raise an
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:class:`~sqlalchemy.exc.InvalidRequestError`.
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This is to prevent applications from accidentally
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continuing an ongoing transactional operations despite the
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fact that the transaction has been lost due to an
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invalidation.
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The :meth:`.Connection.invalidate` method, just like auto-invalidation,
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will at the connection pool level invoke the
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:meth:`.PoolEvents.invalidate` event.
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.. seealso::
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:ref:`pool_connection_invalidation`
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"""
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if self.invalidated:
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return
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|
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if self.closed:
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raise exc.ResourceClosedError("This Connection is closed")
|
|
|
|
if self._root._connection_is_valid:
|
|
self._root.__connection.invalidate(exception)
|
|
del self._root.__connection
|
|
self._root.__invalid = True
|
|
|
|
def detach(self):
|
|
"""Detach the underlying DB-API connection from its connection pool.
|
|
|
|
E.g.::
|
|
|
|
with engine.connect() as conn:
|
|
conn.detach()
|
|
conn.execute("SET search_path TO schema1, schema2")
|
|
|
|
# work with connection
|
|
|
|
# connection is fully closed (since we used "with:", can
|
|
# also call .close())
|
|
|
|
This :class:`.Connection` instance will remain usable. When closed
|
|
(or exited from a context manager context as above),
|
|
the DB-API connection will be literally closed and not
|
|
returned to its originating pool.
|
|
|
|
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).
|
|
|
|
"""
|
|
|
|
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.__branch_from:
|
|
return self.__branch_from.begin()
|
|
|
|
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.__branch_from:
|
|
return self.__branch_from.begin_nested()
|
|
|
|
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.__branch_from:
|
|
return self.__branch_from.begin_twophase(xid=xid)
|
|
|
|
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._root.__transaction is not None
|
|
|
|
def _begin_impl(self, transaction):
|
|
assert not self.__branch_from
|
|
|
|
if self._echo:
|
|
self.engine.logger.info("BEGIN (implicit)")
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.begin(self)
|
|
|
|
try:
|
|
self.engine.dialect.do_begin(self.connection)
|
|
if self.connection._reset_agent is None:
|
|
self.connection._reset_agent = transaction
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
def _rollback_impl(self):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.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)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
finally:
|
|
if not self.__invalid and \
|
|
self.connection._reset_agent is self.__transaction:
|
|
self.connection._reset_agent = None
|
|
self.__transaction = None
|
|
else:
|
|
self.__transaction = None
|
|
|
|
def _commit_impl(self, autocommit=False):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.commit(self)
|
|
|
|
if self._echo:
|
|
self.engine.logger.info("COMMIT")
|
|
try:
|
|
self.engine.dialect.do_commit(self.connection)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
finally:
|
|
if not self.__invalid and \
|
|
self.connection._reset_agent is self.__transaction:
|
|
self.connection._reset_agent = None
|
|
self.__transaction = None
|
|
|
|
def _savepoint_impl(self, name=None):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.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):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.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):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.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, transaction):
|
|
assert not self.__branch_from
|
|
|
|
if self._echo:
|
|
self.engine.logger.info("BEGIN TWOPHASE (implicit)")
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.begin_twophase(self, transaction.xid)
|
|
|
|
if self._still_open_and_connection_is_valid:
|
|
self.engine.dialect.do_begin_twophase(self, transaction.xid)
|
|
|
|
if self.connection._reset_agent is None:
|
|
self.connection._reset_agent = transaction
|
|
|
|
def _prepare_twophase_impl(self, xid):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.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):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.rollback_twophase(self, xid, is_prepared)
|
|
|
|
if self._still_open_and_connection_is_valid:
|
|
assert isinstance(self.__transaction, TwoPhaseTransaction)
|
|
try:
|
|
self.engine.dialect.do_rollback_twophase(
|
|
self, xid, is_prepared)
|
|
finally:
|
|
if self.connection._reset_agent is self.__transaction:
|
|
self.connection._reset_agent = None
|
|
self.__transaction = None
|
|
else:
|
|
self.__transaction = None
|
|
|
|
def _commit_twophase_impl(self, xid, is_prepared):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.commit_twophase(self, xid, is_prepared)
|
|
|
|
if self._still_open_and_connection_is_valid:
|
|
assert isinstance(self.__transaction, TwoPhaseTransaction)
|
|
try:
|
|
self.engine.dialect.do_commit_twophase(self, xid, is_prepared)
|
|
finally:
|
|
if self.connection._reset_agent is self.__transaction:
|
|
self.connection._reset_agent = None
|
|
self.__transaction = None
|
|
else:
|
|
self.__transaction = None
|
|
|
|
def _autorollback(self):
|
|
if not self._root.in_transaction():
|
|
self._root._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.
|
|
|
|
"""
|
|
if self.__branch_from:
|
|
try:
|
|
del self.__connection
|
|
except AttributeError:
|
|
pass
|
|
finally:
|
|
self.__can_reconnect = False
|
|
return
|
|
try:
|
|
conn = self.__connection
|
|
except AttributeError:
|
|
pass
|
|
else:
|
|
|
|
conn.close()
|
|
if conn._reset_agent is self.__transaction:
|
|
conn._reset_agent = None
|
|
|
|
# the close() process can end up invalidating us,
|
|
# as the pool will call our transaction as the "reset_agent"
|
|
# for rollback(), which can then cause an invalidation
|
|
if not self.__invalid:
|
|
del self.__connection
|
|
self.__can_reconnect = False
|
|
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):
|
|
r"""Executes 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 :data:`.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.
|
|
|
|
"""
|
|
if isinstance(object, util.string_types[0]):
|
|
return self._execute_text(object, multiparams, params)
|
|
try:
|
|
meth = object._execute_on_connection
|
|
except AttributeError:
|
|
raise exc.ObjectNotExecutableError(object)
|
|
else:
|
|
return meth(self, multiparams, params)
|
|
|
|
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 or self.engine._has_events:
|
|
for fn in self.dispatch.before_execute:
|
|
default, multiparams, params = \
|
|
fn(self, default, multiparams, params)
|
|
|
|
try:
|
|
try:
|
|
conn = self.__connection
|
|
except AttributeError:
|
|
# escape "except AttributeError" before revalidating
|
|
# to prevent misleading stacktraces in Py3K
|
|
conn = None
|
|
if conn is None:
|
|
conn = self._revalidate_connection()
|
|
|
|
dialect = self.dialect
|
|
ctx = dialect.execution_ctx_cls._init_default(
|
|
dialect, self, conn)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
ret = ctx._exec_default(None, default, None)
|
|
if self.should_close_with_result:
|
|
self.close()
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.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 or self.engine._has_events:
|
|
for fn in self.dispatch.before_execute:
|
|
ddl, multiparams, params = \
|
|
fn(self, ddl, multiparams, params)
|
|
|
|
dialect = self.dialect
|
|
|
|
compiled = ddl.compile(
|
|
dialect=dialect,
|
|
schema_translate_map=self.schema_for_object
|
|
if not self.schema_for_object.is_default else None)
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_ddl,
|
|
compiled,
|
|
None,
|
|
compiled
|
|
)
|
|
if self._has_events or self.engine._has_events:
|
|
self.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 or self.engine._has_events:
|
|
for fn in self.dispatch.before_execute:
|
|
elem, multiparams, params = \
|
|
fn(self, elem, multiparams, params)
|
|
|
|
distilled_params = _distill_params(multiparams, params)
|
|
if distilled_params:
|
|
# note this is usually dict but we support RowProxy
|
|
# as well; but dict.keys() as an iterable is OK
|
|
keys = distilled_params[0].keys()
|
|
else:
|
|
keys = []
|
|
|
|
dialect = self.dialect
|
|
if 'compiled_cache' in self._execution_options:
|
|
key = (
|
|
dialect, elem, tuple(sorted(keys)),
|
|
self.schema_for_object.hash_key,
|
|
len(distilled_params) > 1
|
|
)
|
|
compiled_sql = self._execution_options['compiled_cache'].get(key)
|
|
if compiled_sql is None:
|
|
compiled_sql = elem.compile(
|
|
dialect=dialect, column_keys=keys,
|
|
inline=len(distilled_params) > 1,
|
|
schema_translate_map=self.schema_for_object
|
|
if not self.schema_for_object.is_default else None
|
|
)
|
|
self._execution_options['compiled_cache'][key] = compiled_sql
|
|
else:
|
|
compiled_sql = elem.compile(
|
|
dialect=dialect, column_keys=keys,
|
|
inline=len(distilled_params) > 1,
|
|
schema_translate_map=self.schema_for_object
|
|
if not self.schema_for_object.is_default else None)
|
|
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_compiled,
|
|
compiled_sql,
|
|
distilled_params,
|
|
compiled_sql, distilled_params
|
|
)
|
|
if self._has_events or self.engine._has_events:
|
|
self.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 or self.engine._has_events:
|
|
for fn in self.dispatch.before_execute:
|
|
compiled, multiparams, params = \
|
|
fn(self, compiled, multiparams, params)
|
|
|
|
dialect = self.dialect
|
|
parameters = _distill_params(multiparams, params)
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_compiled,
|
|
compiled,
|
|
parameters,
|
|
compiled, parameters
|
|
)
|
|
if self._has_events or self.engine._has_events:
|
|
self.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 or self.engine._has_events:
|
|
for fn in self.dispatch.before_execute:
|
|
statement, multiparams, params = \
|
|
fn(self, statement, multiparams, params)
|
|
|
|
dialect = self.dialect
|
|
parameters = _distill_params(multiparams, params)
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_statement,
|
|
statement,
|
|
parameters,
|
|
statement, parameters
|
|
)
|
|
if self._has_events or self.engine._has_events:
|
|
self.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:
|
|
# escape "except AttributeError" before revalidating
|
|
# to prevent misleading stacktraces in Py3K
|
|
conn = None
|
|
if conn is None:
|
|
conn = self._revalidate_connection()
|
|
|
|
context = constructor(dialect, self, conn, *args)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(
|
|
e,
|
|
util.text_type(statement), parameters,
|
|
None, None)
|
|
|
|
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 or self.engine._has_events:
|
|
for fn in self.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)
|
|
)
|
|
|
|
evt_handled = False
|
|
try:
|
|
if context.executemany:
|
|
if self.dialect._has_events:
|
|
for fn in self.dialect.dispatch.do_executemany:
|
|
if fn(cursor, statement, parameters, context):
|
|
evt_handled = True
|
|
break
|
|
if not evt_handled:
|
|
self.dialect.do_executemany(
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context)
|
|
elif not parameters and context.no_parameters:
|
|
if self.dialect._has_events:
|
|
for fn in self.dialect.dispatch.do_execute_no_params:
|
|
if fn(cursor, statement, context):
|
|
evt_handled = True
|
|
break
|
|
if not evt_handled:
|
|
self.dialect.do_execute_no_params(
|
|
cursor,
|
|
statement,
|
|
context)
|
|
else:
|
|
if self.dialect._has_events:
|
|
for fn in self.dialect.dispatch.do_execute:
|
|
if fn(cursor, statement, parameters, context):
|
|
evt_handled = True
|
|
break
|
|
if not evt_handled:
|
|
self.dialect.do_execute(
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(
|
|
e,
|
|
statement,
|
|
parameters,
|
|
cursor,
|
|
context)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_cursor_execute(self, cursor,
|
|
statement,
|
|
parameters,
|
|
context,
|
|
context.executemany)
|
|
|
|
if context.compiled:
|
|
context.post_exec()
|
|
|
|
if context.is_crud or context.is_text:
|
|
result = context._setup_crud_result_proxy()
|
|
else:
|
|
result = context.get_result_proxy()
|
|
if result._metadata is None:
|
|
result._soft_close()
|
|
|
|
if context.should_autocommit and self._root.__transaction is None:
|
|
self._root._commit_impl(autocommit=True)
|
|
|
|
# for "connectionless" execution, we have to close this
|
|
# Connection after the statement is complete.
|
|
if self.should_close_with_result:
|
|
# ResultProxy already exhausted rows / has no rows.
|
|
# close us now
|
|
if result._soft_closed:
|
|
self.close()
|
|
else:
|
|
# ResultProxy will close this Connection when no more
|
|
# rows to fetch.
|
|
result._autoclose_connection = True
|
|
return result
|
|
|
|
def _cursor_execute(self, cursor, statement, parameters, context=None):
|
|
"""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._has_events or self.engine._has_events:
|
|
for fn in self.dispatch.before_cursor_execute:
|
|
statement, parameters = \
|
|
fn(self, cursor, statement, parameters,
|
|
context,
|
|
False)
|
|
|
|
if self._echo:
|
|
self.engine.logger.info(statement)
|
|
self.engine.logger.info("%r", parameters)
|
|
try:
|
|
for fn in () if not self.dialect._has_events \
|
|
else self.dialect.dispatch.do_execute:
|
|
if fn(cursor, statement, parameters, context):
|
|
break
|
|
else:
|
|
self.dialect.do_execute(
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(
|
|
e,
|
|
statement,
|
|
parameters,
|
|
cursor,
|
|
context)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_cursor_execute(self, cursor,
|
|
statement,
|
|
parameters,
|
|
context,
|
|
False)
|
|
|
|
def _safe_close_cursor(self, cursor):
|
|
"""Close the given cursor, catching exceptions
|
|
and turning into log warnings.
|
|
|
|
"""
|
|
try:
|
|
cursor.close()
|
|
except Exception:
|
|
# log the error through the connection pool's logger.
|
|
self.engine.pool.logger.error(
|
|
"Error closing cursor", exc_info=True)
|
|
|
|
_reentrant_error = False
|
|
_is_disconnect = False
|
|
|
|
def _handle_dbapi_exception(self,
|
|
e,
|
|
statement,
|
|
parameters,
|
|
cursor,
|
|
context):
|
|
exc_info = sys.exc_info()
|
|
|
|
if context and context.exception is None:
|
|
context.exception = e
|
|
|
|
is_exit_exception = not isinstance(e, Exception)
|
|
|
|
if not self._is_disconnect:
|
|
self._is_disconnect = (
|
|
isinstance(e, self.dialect.dbapi.Error) and
|
|
not self.closed and
|
|
self.dialect.is_disconnect(
|
|
e,
|
|
self.__connection if not self.invalidated else None,
|
|
cursor)
|
|
) or (
|
|
is_exit_exception and not self.closed
|
|
)
|
|
|
|
if context:
|
|
context.is_disconnect = self._is_disconnect
|
|
|
|
invalidate_pool_on_disconnect = not is_exit_exception
|
|
|
|
if self._reentrant_error:
|
|
util.raise_from_cause(
|
|
exc.DBAPIError.instance(statement,
|
|
parameters,
|
|
e,
|
|
self.dialect.dbapi.Error,
|
|
dialect=self.dialect),
|
|
exc_info
|
|
)
|
|
self._reentrant_error = True
|
|
try:
|
|
# non-DBAPI error - if we already got a context,
|
|
# or there's no string statement, don't wrap it
|
|
should_wrap = isinstance(e, self.dialect.dbapi.Error) or \
|
|
(statement is not None
|
|
and context is None and not is_exit_exception)
|
|
|
|
if should_wrap:
|
|
sqlalchemy_exception = exc.DBAPIError.instance(
|
|
statement,
|
|
parameters,
|
|
e,
|
|
self.dialect.dbapi.Error,
|
|
connection_invalidated=self._is_disconnect,
|
|
dialect=self.dialect)
|
|
else:
|
|
sqlalchemy_exception = None
|
|
|
|
newraise = None
|
|
|
|
if (self._has_events or self.engine._has_events) and \
|
|
not self._execution_options.get(
|
|
'skip_user_error_events', False):
|
|
# legacy dbapi_error event
|
|
if should_wrap and context:
|
|
self.dispatch.dbapi_error(self,
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context,
|
|
e)
|
|
|
|
# new handle_error event
|
|
ctx = ExceptionContextImpl(
|
|
e, sqlalchemy_exception, self.engine,
|
|
self, cursor, statement,
|
|
parameters, context, self._is_disconnect,
|
|
invalidate_pool_on_disconnect)
|
|
|
|
for fn in self.dispatch.handle_error:
|
|
try:
|
|
# handler returns an exception;
|
|
# call next handler in a chain
|
|
per_fn = fn(ctx)
|
|
if per_fn is not None:
|
|
ctx.chained_exception = newraise = per_fn
|
|
except Exception as _raised:
|
|
# handler raises an exception - stop processing
|
|
newraise = _raised
|
|
break
|
|
|
|
if self._is_disconnect != ctx.is_disconnect:
|
|
self._is_disconnect = ctx.is_disconnect
|
|
if sqlalchemy_exception:
|
|
sqlalchemy_exception.connection_invalidated = \
|
|
ctx.is_disconnect
|
|
|
|
# set up potentially user-defined value for
|
|
# invalidate pool.
|
|
invalidate_pool_on_disconnect = \
|
|
ctx.invalidate_pool_on_disconnect
|
|
|
|
if should_wrap and context:
|
|
context.handle_dbapi_exception(e)
|
|
|
|
if not self._is_disconnect:
|
|
if cursor:
|
|
self._safe_close_cursor(cursor)
|
|
with util.safe_reraise(warn_only=True):
|
|
self._autorollback()
|
|
|
|
if newraise:
|
|
util.raise_from_cause(newraise, exc_info)
|
|
elif should_wrap:
|
|
util.raise_from_cause(
|
|
sqlalchemy_exception,
|
|
exc_info
|
|
)
|
|
else:
|
|
util.reraise(*exc_info)
|
|
|
|
finally:
|
|
del self._reentrant_error
|
|
if self._is_disconnect:
|
|
del self._is_disconnect
|
|
if not self.invalidated:
|
|
dbapi_conn_wrapper = self.__connection
|
|
if invalidate_pool_on_disconnect:
|
|
self.engine.pool._invalidate(dbapi_conn_wrapper, e)
|
|
self.invalidate(e)
|
|
if self.should_close_with_result:
|
|
self.close()
|
|
|
|
@classmethod
|
|
def _handle_dbapi_exception_noconnection(cls, e, dialect, engine):
|
|
exc_info = sys.exc_info()
|
|
|
|
is_disconnect = dialect.is_disconnect(e, None, None)
|
|
|
|
should_wrap = isinstance(e, dialect.dbapi.Error)
|
|
|
|
if should_wrap:
|
|
sqlalchemy_exception = exc.DBAPIError.instance(
|
|
None,
|
|
None,
|
|
e,
|
|
dialect.dbapi.Error,
|
|
connection_invalidated=is_disconnect)
|
|
else:
|
|
sqlalchemy_exception = None
|
|
|
|
newraise = None
|
|
|
|
if engine._has_events:
|
|
ctx = ExceptionContextImpl(
|
|
e, sqlalchemy_exception, engine, None, None, None,
|
|
None, None, is_disconnect, True)
|
|
for fn in engine.dispatch.handle_error:
|
|
try:
|
|
# handler returns an exception;
|
|
# call next handler in a chain
|
|
per_fn = fn(ctx)
|
|
if per_fn is not None:
|
|
ctx.chained_exception = newraise = per_fn
|
|
except Exception as _raised:
|
|
# handler raises an exception - stop processing
|
|
newraise = _raised
|
|
break
|
|
|
|
if sqlalchemy_exception and \
|
|
is_disconnect != ctx.is_disconnect:
|
|
sqlalchemy_exception.connection_invalidated = \
|
|
is_disconnect = ctx.is_disconnect
|
|
|
|
if newraise:
|
|
util.raise_from_cause(newraise, exc_info)
|
|
elif should_wrap:
|
|
util.raise_from_cause(
|
|
sqlalchemy_exception,
|
|
exc_info
|
|
)
|
|
else:
|
|
util.reraise(*exc_info)
|
|
|
|
def transaction(self, callable_, *args, **kwargs):
|
|
r"""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:
|
|
with util.safe_reraise():
|
|
trans.rollback()
|
|
|
|
def run_callable(self, callable_, *args, **kwargs):
|
|
r"""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 ExceptionContextImpl(ExceptionContext):
|
|
"""Implement the :class:`.ExceptionContext` interface."""
|
|
|
|
def __init__(self, exception, sqlalchemy_exception,
|
|
engine, connection, cursor, statement, parameters,
|
|
context, is_disconnect, invalidate_pool_on_disconnect):
|
|
self.engine = engine
|
|
self.connection = connection
|
|
self.sqlalchemy_exception = sqlalchemy_exception
|
|
self.original_exception = exception
|
|
self.execution_context = context
|
|
self.statement = statement
|
|
self.parameters = parameters
|
|
self.is_disconnect = is_disconnect
|
|
self.invalidate_pool_on_disconnect = invalidate_pool_on_disconnect
|
|
|
|
|
|
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._actual_parent = parent
|
|
self.is_active = True
|
|
|
|
@property
|
|
def _parent(self):
|
|
return self._actual_parent or self
|
|
|
|
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:
|
|
with util.safe_reraise():
|
|
self.rollback()
|
|
else:
|
|
self.rollback()
|
|
|
|
|
|
class RootTransaction(Transaction):
|
|
def __init__(self, connection):
|
|
super(RootTransaction, self).__init__(connection, None)
|
|
self.connection._begin_impl(self)
|
|
|
|
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)
|
|
|
|
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.interfaces.Dialect` together to provide a
|
|
source of database connectivity and behavior.
|
|
|
|
An :class:`.Engine` object is instantiated publicly using the
|
|
:func:`~sqlalchemy.create_engine` function.
|
|
|
|
See also:
|
|
|
|
:doc:`/core/engines`
|
|
|
|
:ref:`connections_toplevel`
|
|
|
|
"""
|
|
|
|
_execution_options = util.immutabledict()
|
|
_has_events = False
|
|
_connection_cls = Connection
|
|
|
|
schema_for_object = schema._schema_getter(None)
|
|
"""Return the ".schema" attribute for an object.
|
|
|
|
Used for :class:`.Table`, :class:`.Sequence` and similar objects,
|
|
and takes into account
|
|
the :paramref:`.Connection.execution_options.schema_translate_map`
|
|
parameter.
|
|
|
|
.. versionadded:: 1.1
|
|
|
|
.. seealso::
|
|
|
|
:ref:`schema_translating`
|
|
|
|
"""
|
|
|
|
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:
|
|
self.update_execution_options(**execution_options)
|
|
|
|
def update_execution_options(self, **opt):
|
|
r"""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`` parameter
|
|
to :func:`.create_engine`.
|
|
|
|
.. seealso::
|
|
|
|
:meth:`.Connection.execution_options`
|
|
|
|
:meth:`.Engine.execution_options`
|
|
|
|
"""
|
|
self._execution_options = \
|
|
self._execution_options.union(opt)
|
|
self.dispatch.set_engine_execution_options(self, opt)
|
|
self.dialect.set_engine_execution_options(self, opt)
|
|
|
|
def execution_options(self, **opt):
|
|
"""Return a new :class:`.Engine` that will provide
|
|
:class:`.Connection` objects with the given execution options.
|
|
|
|
The returned :class:`.Engine` remains related to the original
|
|
:class:`.Engine` in that it shares the same connection pool and
|
|
other state:
|
|
|
|
* The :class:`.Pool` used by the new :class:`.Engine` is the
|
|
same instance. The :meth:`.Engine.dispose` method will replace
|
|
the connection pool instance for the parent engine as well
|
|
as this one.
|
|
* Event listeners are "cascaded" - meaning, the new :class:`.Engine`
|
|
inherits the events of the parent, and new events can be associated
|
|
with the new :class:`.Engine` individually.
|
|
* The logging configuration and logging_name is copied from the parent
|
|
:class:`.Engine`.
|
|
|
|
The intent of the :meth:`.Engine.execution_options` method is
|
|
to implement "sharding" schemes where multiple :class:`.Engine`
|
|
objects refer to the same connection pool, but are differentiated
|
|
by options that would be consumed by a custom event::
|
|
|
|
primary_engine = create_engine("mysql://")
|
|
shard1 = primary_engine.execution_options(shard_id="shard1")
|
|
shard2 = primary_engine.execution_options(shard_id="shard2")
|
|
|
|
Above, the ``shard1`` engine serves as a factory for
|
|
:class:`.Connection` objects that will contain the execution option
|
|
``shard_id=shard1``, and ``shard2`` will produce :class:`.Connection`
|
|
objects that contain the execution option ``shard_id=shard2``.
|
|
|
|
An event handler can consume the above execution option to perform
|
|
a schema switch or other operation, given a connection. Below
|
|
we emit a MySQL ``use`` statement to switch databases, at the same
|
|
time keeping track of which database we've established using the
|
|
:attr:`.Connection.info` dictionary, which gives us a persistent
|
|
storage space that follows the DBAPI connection::
|
|
|
|
from sqlalchemy import event
|
|
from sqlalchemy.engine import Engine
|
|
|
|
shards = {"default": "base", shard_1: "db1", "shard_2": "db2"}
|
|
|
|
@event.listens_for(Engine, "before_cursor_execute")
|
|
def _switch_shard(conn, cursor, stmt,
|
|
params, context, executemany):
|
|
shard_id = conn._execution_options.get('shard_id', "default")
|
|
current_shard = conn.info.get("current_shard", None)
|
|
|
|
if current_shard != shard_id:
|
|
cursor.execute("use %s" % shards[shard_id])
|
|
conn.info["current_shard"] = shard_id
|
|
|
|
.. versionadded:: 0.8
|
|
|
|
.. seealso::
|
|
|
|
:meth:`.Connection.execution_options` - update execution options
|
|
on a :class:`.Connection` object.
|
|
|
|
:meth:`.Engine.update_execution_options` - update the execution
|
|
options for a given :class:`.Engine` in place.
|
|
|
|
"""
|
|
return OptionEngine(self, opt)
|
|
|
|
@property
|
|
def name(self):
|
|
"""String name of the :class:`~sqlalchemy.engine.interfaces.Dialect`
|
|
in use by this :class:`Engine`."""
|
|
|
|
return self.dialect.name
|
|
|
|
@property
|
|
def driver(self):
|
|
"""Driver name of the :class:`~sqlalchemy.engine.interfaces.Dialect`
|
|
in use by this :class:`Engine`."""
|
|
|
|
return self.dialect.driver
|
|
|
|
echo = log.echo_property()
|
|
|
|
def __repr__(self):
|
|
return 'Engine(%r)' % self.url
|
|
|
|
def dispose(self):
|
|
"""Dispose of the connection pool used by this :class:`.Engine`.
|
|
|
|
This has the effect of fully closing all **currently checked in**
|
|
database connections. Connections that are still checked out
|
|
will **not** be closed, however they will no longer be associated
|
|
with this :class:`.Engine`, so when they are closed individually,
|
|
eventually the :class:`.Pool` which they are associated with will
|
|
be garbage collected and they will be closed out fully, if
|
|
not already closed on checkin.
|
|
|
|
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, so as long as the :class:`.Engine` isn't used again,
|
|
no new connections will be made.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`engine_disposal`
|
|
|
|
"""
|
|
self.pool.dispose()
|
|
self.pool = self.pool.recreate()
|
|
self.dispatch.engine_disposed(self)
|
|
|
|
def _execute_default(self, default):
|
|
with self.contextual_connect() as conn:
|
|
return conn._execute_default(default, (), {})
|
|
|
|
@contextlib.contextmanager
|
|
def _optional_conn_ctx_manager(self, connection=None):
|
|
if connection is None:
|
|
with self.contextual_connect() as conn:
|
|
yield conn
|
|
else:
|
|
yield connection
|
|
|
|
def _run_visitor(self, visitorcallable, element,
|
|
connection=None, **kwargs):
|
|
with self._optional_conn_ctx_manager(connection) as conn:
|
|
conn._run_visitor(visitorcallable, element, **kwargs)
|
|
|
|
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.
|
|
|
|
.. versionadded:: 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)
|
|
try:
|
|
trans = conn.begin()
|
|
except:
|
|
with util.safe_reraise():
|
|
conn.close()
|
|
return Engine._trans_ctx(conn, trans, close_with_result)
|
|
|
|
def transaction(self, callable_, *args, **kwargs):
|
|
r"""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`
|
|
|
|
"""
|
|
|
|
with self.contextual_connect() as conn:
|
|
return conn.transaction(callable_, *args, **kwargs)
|
|
|
|
def run_callable(self, callable_, *args, **kwargs):
|
|
r"""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.
|
|
|
|
"""
|
|
with self.contextual_connect() as conn:
|
|
return conn.run_callable(callable_, *args, **kwargs)
|
|
|
|
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._wrap_pool_connect(self.pool.connect, None),
|
|
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``.
|
|
"""
|
|
|
|
with self._optional_conn_ctx_manager(connection) as conn:
|
|
if not schema:
|
|
schema = self.dialect.default_schema_name
|
|
return self.dialect.get_table_names(conn, schema)
|
|
|
|
def has_table(self, table_name, schema=None):
|
|
"""Return True if the given backend has a table of the given name.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`metadata_reflection_inspector` - detailed schema inspection
|
|
using the :class:`.Inspector` interface.
|
|
|
|
:class:`.quoted_name` - used to pass quoting information along
|
|
with a schema identifier.
|
|
|
|
"""
|
|
return self.run_callable(self.dialect.has_table, table_name, schema)
|
|
|
|
def _wrap_pool_connect(self, fn, connection):
|
|
dialect = self.dialect
|
|
try:
|
|
return fn()
|
|
except dialect.dbapi.Error as e:
|
|
if connection is None:
|
|
Connection._handle_dbapi_exception_noconnection(
|
|
e, dialect, self)
|
|
else:
|
|
util.reraise(*sys.exc_info())
|
|
|
|
def raw_connection(self, _connection=None):
|
|
"""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 when the API provided by :class:`.Connection`
|
|
is not needed. When a :class:`.Connection` object is already
|
|
present, the DBAPI connection is available using
|
|
the :attr:`.Connection.connection` accessor.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`dbapi_connections`
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|
|
|
"""
|
|
return self._wrap_pool_connect(
|
|
self.pool.unique_connection, _connection)
|
|
|
|
|
|
class OptionEngine(Engine):
|
|
_sa_propagate_class_events = False
|
|
|
|
def __init__(self, proxied, execution_options):
|
|
self._proxied = proxied
|
|
self.url = proxied.url
|
|
self.dialect = proxied.dialect
|
|
self.logging_name = proxied.logging_name
|
|
self.echo = proxied.echo
|
|
log.instance_logger(self, echoflag=self.echo)
|
|
|
|
# note: this will propagate events that are assigned to the parent
|
|
# engine after this OptionEngine is created. Since we share
|
|
# the events of the parent we also disallow class-level events
|
|
# to apply to the OptionEngine class directly.
|
|
#
|
|
# the other way this can work would be to transfer existing
|
|
# events only, using:
|
|
# self.dispatch._update(proxied.dispatch)
|
|
#
|
|
# that might be more appropriate however it would be a behavioral
|
|
# change for logic that assigns events to the parent engine and
|
|
# would like it to take effect for the already-created sub-engine.
|
|
self.dispatch = self.dispatch._join(proxied.dispatch)
|
|
|
|
self._execution_options = proxied._execution_options
|
|
self.update_execution_options(**execution_options)
|
|
|
|
def _get_pool(self):
|
|
return self._proxied.pool
|
|
|
|
def _set_pool(self, pool):
|
|
self._proxied.pool = pool
|
|
|
|
pool = property(_get_pool, _set_pool)
|
|
|
|
def _get_has_events(self):
|
|
return self._proxied._has_events or \
|
|
self.__dict__.get('_has_events', False)
|
|
|
|
def _set_has_events(self, value):
|
|
self.__dict__['_has_events'] = value
|
|
|
|
_has_events = property(_get_has_events, _set_has_events)
|