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836 lines
33 KiB
Python
836 lines
33 KiB
Python
3 months ago
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# sqlalchemy/engine/events.py
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# Copyright (C) 2005-2022 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: https://www.opensource.org/licenses/mit-license.php
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from .base import Engine
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from .interfaces import Connectable
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from .interfaces import Dialect
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from .. import event
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from .. import exc
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class ConnectionEvents(event.Events):
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"""Available events for :class:`.Connectable`, which includes
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:class:`_engine.Connection` and :class:`_engine.Engine`.
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The methods here define the name of an event as well as the names of
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members that are passed to listener functions.
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An event listener can be associated with any :class:`.Connectable`
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class or instance, such as an :class:`_engine.Engine`, e.g.::
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from sqlalchemy import event, create_engine
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def before_cursor_execute(conn, cursor, statement, parameters, context,
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executemany):
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log.info("Received statement: %s", statement)
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engine = create_engine('postgresql://scott:tiger@localhost/test')
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event.listen(engine, "before_cursor_execute", before_cursor_execute)
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or with a specific :class:`_engine.Connection`::
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with engine.begin() as conn:
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@event.listens_for(conn, 'before_cursor_execute')
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def before_cursor_execute(conn, cursor, statement, parameters,
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context, executemany):
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log.info("Received statement: %s", statement)
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When the methods are called with a `statement` parameter, such as in
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:meth:`.after_cursor_execute` or :meth:`.before_cursor_execute`,
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the statement is the exact SQL string that was prepared for transmission
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to the DBAPI ``cursor`` in the connection's :class:`.Dialect`.
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The :meth:`.before_execute` and :meth:`.before_cursor_execute`
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events can also be established with the ``retval=True`` flag, which
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allows modification of the statement and parameters to be sent
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to the database. The :meth:`.before_cursor_execute` event is
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particularly useful here to add ad-hoc string transformations, such
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as comments, to all executions::
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from sqlalchemy.engine import Engine
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from sqlalchemy import event
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@event.listens_for(Engine, "before_cursor_execute", retval=True)
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def comment_sql_calls(conn, cursor, statement, parameters,
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context, executemany):
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statement = statement + " -- some comment"
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return statement, parameters
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.. note:: :class:`_events.ConnectionEvents` can be established on any
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combination of :class:`_engine.Engine`, :class:`_engine.Connection`,
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as well
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as instances of each of those classes. Events across all
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four scopes will fire off for a given instance of
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:class:`_engine.Connection`. However, for performance reasons, the
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:class:`_engine.Connection` object determines at instantiation time
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whether or not its parent :class:`_engine.Engine` has event listeners
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established. Event listeners added to the :class:`_engine.Engine`
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class or to an instance of :class:`_engine.Engine`
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*after* the instantiation
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of a dependent :class:`_engine.Connection` instance will usually
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*not* be available on that :class:`_engine.Connection` instance.
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The newly
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added listeners will instead take effect for
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:class:`_engine.Connection`
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instances created subsequent to those event listeners being
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established on the parent :class:`_engine.Engine` class or instance.
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:param retval=False: Applies to the :meth:`.before_execute` and
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:meth:`.before_cursor_execute` events only. When True, the
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user-defined event function must have a return value, which
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is a tuple of parameters that replace the given statement
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and parameters. See those methods for a description of
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specific return arguments.
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"""
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_target_class_doc = "SomeEngine"
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_dispatch_target = Connectable
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@classmethod
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def _listen(cls, event_key, retval=False):
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target, identifier, fn = (
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event_key.dispatch_target,
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event_key.identifier,
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event_key._listen_fn,
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)
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target._has_events = True
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if not retval:
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if identifier == "before_execute":
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orig_fn = fn
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def wrap_before_execute(
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conn, clauseelement, multiparams, params, execution_options
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):
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orig_fn(
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conn,
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clauseelement,
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multiparams,
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params,
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execution_options,
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)
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return clauseelement, multiparams, params
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fn = wrap_before_execute
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elif identifier == "before_cursor_execute":
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orig_fn = fn
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def wrap_before_cursor_execute(
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conn, cursor, statement, parameters, context, executemany
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):
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orig_fn(
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conn,
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cursor,
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statement,
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parameters,
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context,
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executemany,
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)
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return statement, parameters
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fn = wrap_before_cursor_execute
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elif retval and identifier not in (
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"before_execute",
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"before_cursor_execute",
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"handle_error",
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):
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raise exc.ArgumentError(
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"Only the 'before_execute', "
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"'before_cursor_execute' and 'handle_error' engine "
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"event listeners accept the 'retval=True' "
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"argument."
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)
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event_key.with_wrapper(fn).base_listen()
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@event._legacy_signature(
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"1.4",
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["conn", "clauseelement", "multiparams", "params"],
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lambda conn, clauseelement, multiparams, params, execution_options: (
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conn,
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clauseelement,
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multiparams,
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params,
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),
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)
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def before_execute(
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self, conn, clauseelement, multiparams, params, execution_options
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):
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"""Intercept high level execute() events, receiving uncompiled
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SQL constructs and other objects prior to rendering into SQL.
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This event is good for debugging SQL compilation issues as well
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as early manipulation of the parameters being sent to the database,
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as the parameter lists will be in a consistent format here.
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This event can be optionally established with the ``retval=True``
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flag. The ``clauseelement``, ``multiparams``, and ``params``
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arguments should be returned as a three-tuple in this case::
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@event.listens_for(Engine, "before_execute", retval=True)
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def before_execute(conn, clauseelement, multiparams, params):
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# do something with clauseelement, multiparams, params
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return clauseelement, multiparams, params
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:param conn: :class:`_engine.Connection` object
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:param clauseelement: SQL expression construct, :class:`.Compiled`
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instance, or string statement passed to
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:meth:`_engine.Connection.execute`.
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:param multiparams: Multiple parameter sets, a list of dictionaries.
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:param params: Single parameter set, a single dictionary.
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:param execution_options: dictionary of execution
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options passed along with the statement, if any. This is a merge
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of all options that will be used, including those of the statement,
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the connection, and those passed in to the method itself for
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the 2.0 style of execution.
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.. versionadded: 1.4
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.. seealso::
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:meth:`.before_cursor_execute`
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"""
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@event._legacy_signature(
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"1.4",
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["conn", "clauseelement", "multiparams", "params", "result"],
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lambda conn, clauseelement, multiparams, params, execution_options, result: ( # noqa
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conn,
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clauseelement,
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multiparams,
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params,
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result,
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),
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)
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def after_execute(
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self,
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conn,
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clauseelement,
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multiparams,
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params,
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execution_options,
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result,
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):
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"""Intercept high level execute() events after execute.
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:param conn: :class:`_engine.Connection` object
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:param clauseelement: SQL expression construct, :class:`.Compiled`
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instance, or string statement passed to
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:meth:`_engine.Connection.execute`.
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:param multiparams: Multiple parameter sets, a list of dictionaries.
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:param params: Single parameter set, a single dictionary.
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:param execution_options: dictionary of execution
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options passed along with the statement, if any. This is a merge
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of all options that will be used, including those of the statement,
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the connection, and those passed in to the method itself for
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the 2.0 style of execution.
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.. versionadded: 1.4
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:param result: :class:`_engine.CursorResult` generated by the
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execution.
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"""
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def before_cursor_execute(
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self, conn, cursor, statement, parameters, context, executemany
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):
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"""Intercept low-level cursor execute() events before execution,
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receiving the string SQL statement and DBAPI-specific parameter list to
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be invoked against a cursor.
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This event is a good choice for logging as well as late modifications
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to the SQL string. It's less ideal for parameter modifications except
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for those which are specific to a target backend.
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This event can be optionally established with the ``retval=True``
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flag. The ``statement`` and ``parameters`` arguments should be
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returned as a two-tuple in this case::
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@event.listens_for(Engine, "before_cursor_execute", retval=True)
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def before_cursor_execute(conn, cursor, statement,
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parameters, context, executemany):
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# do something with statement, parameters
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return statement, parameters
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See the example at :class:`_events.ConnectionEvents`.
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:param conn: :class:`_engine.Connection` object
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:param cursor: DBAPI cursor object
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:param statement: string SQL statement, as to be passed to the DBAPI
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:param parameters: Dictionary, tuple, or list of parameters being
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passed to the ``execute()`` or ``executemany()`` method of the
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DBAPI ``cursor``. In some cases may be ``None``.
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:param context: :class:`.ExecutionContext` object in use. May
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be ``None``.
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:param executemany: boolean, if ``True``, this is an ``executemany()``
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call, if ``False``, this is an ``execute()`` call.
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.. seealso::
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:meth:`.before_execute`
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:meth:`.after_cursor_execute`
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"""
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def after_cursor_execute(
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self, conn, cursor, statement, parameters, context, executemany
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):
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"""Intercept low-level cursor execute() events after execution.
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:param conn: :class:`_engine.Connection` object
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:param cursor: DBAPI cursor object. Will have results pending
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if the statement was a SELECT, but these should not be consumed
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as they will be needed by the :class:`_engine.CursorResult`.
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:param statement: string SQL statement, as passed to the DBAPI
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:param parameters: Dictionary, tuple, or list of parameters being
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passed to the ``execute()`` or ``executemany()`` method of the
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DBAPI ``cursor``. In some cases may be ``None``.
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:param context: :class:`.ExecutionContext` object in use. May
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be ``None``.
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:param executemany: boolean, if ``True``, this is an ``executemany()``
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call, if ``False``, this is an ``execute()`` call.
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"""
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def handle_error(self, exception_context):
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r"""Intercept all exceptions processed by the
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:class:`_engine.Connection`.
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This includes all exceptions emitted by the DBAPI as well as
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within SQLAlchemy's statement invocation process, including
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encoding errors and other statement validation errors. Other areas
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in which the event is invoked include transaction begin and end,
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result row fetching, cursor creation.
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Note that :meth:`.handle_error` may support new kinds of exceptions
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and new calling scenarios at *any time*. Code which uses this
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event must expect new calling patterns to be present in minor
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releases.
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To support the wide variety of members that correspond to an exception,
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as well as to allow extensibility of the event without backwards
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incompatibility, the sole argument received is an instance of
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:class:`.ExceptionContext`. This object contains data members
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representing detail about the exception.
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Use cases supported by this hook include:
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|
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* read-only, low-level exception handling for logging and
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debugging purposes
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* exception re-writing
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* Establishing or disabling whether a connection or the owning
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connection pool is invalidated or expired in response to a
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specific exception [1]_.
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The hook is called while the cursor from the failed operation
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(if any) is still open and accessible. Special cleanup operations
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can be called on this cursor; SQLAlchemy will attempt to close
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this cursor subsequent to this hook being invoked. If the connection
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is in "autocommit" mode, the transaction also remains open within
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the scope of this hook; the rollback of the per-statement transaction
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also occurs after the hook is called.
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.. note::
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.. [1] The pool "pre_ping" handler enabled using the
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:paramref:`_sa.create_engine.pool_pre_ping` parameter does
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**not** consult this event before deciding if the "ping"
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returned false, as opposed to receiving an unhandled error.
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For this use case, the :ref:`legacy recipe based on
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engine_connect() may be used
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<pool_disconnects_pessimistic_custom>`. A future API allow
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more comprehensive customization of the "disconnect"
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detection mechanism across all functions.
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|
|
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A handler function has two options for replacing
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the SQLAlchemy-constructed exception into one that is user
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defined. It can either raise this new exception directly, in
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which case all further event listeners are bypassed and the
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|
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exception will be raised, after appropriate cleanup as taken
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place::
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|
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|
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@event.listens_for(Engine, "handle_error")
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|
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def handle_exception(context):
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|
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if isinstance(context.original_exception,
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|
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psycopg2.OperationalError) and \
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"failed" in str(context.original_exception):
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raise MySpecialException("failed operation")
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|
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.. warning:: Because the
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|
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:meth:`_events.ConnectionEvents.handle_error`
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||
|
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event specifically provides for exceptions to be re-thrown as
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||
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the ultimate exception raised by the failed statement,
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**stack traces will be misleading** if the user-defined event
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||
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handler itself fails and throws an unexpected exception;
|
||
|
|
the stack trace may not illustrate the actual code line that
|
||
|
|
failed! It is advised to code carefully here and use
|
||
|
|
logging and/or inline debugging if unexpected exceptions are
|
||
|
|
occurring.
|
||
|
|
|
||
|
|
Alternatively, a "chained" style of event handling can be
|
||
|
|
used, by configuring the handler with the ``retval=True``
|
||
|
|
modifier and returning the new exception instance from the
|
||
|
|
function. In this case, event handling will continue onto the
|
||
|
|
next handler. The "chained" exception is available using
|
||
|
|
:attr:`.ExceptionContext.chained_exception`::
|
||
|
|
|
||
|
|
@event.listens_for(Engine, "handle_error", retval=True)
|
||
|
|
def handle_exception(context):
|
||
|
|
if context.chained_exception is not None and \
|
||
|
|
"special" in context.chained_exception.message:
|
||
|
|
return MySpecialException("failed",
|
||
|
|
cause=context.chained_exception)
|
||
|
|
|
||
|
|
Handlers that return ``None`` may be used within the chain; when
|
||
|
|
a handler returns ``None``, the previous exception instance,
|
||
|
|
if any, is maintained as the current exception that is passed onto the
|
||
|
|
next handler.
|
||
|
|
|
||
|
|
When a custom exception is raised or returned, SQLAlchemy raises
|
||
|
|
this new exception as-is, it is not wrapped by any SQLAlchemy
|
||
|
|
object. If the exception is not a subclass of
|
||
|
|
:class:`sqlalchemy.exc.StatementError`,
|
||
|
|
certain features may not be available; currently this includes
|
||
|
|
the ORM's feature of adding a detail hint about "autoflush" to
|
||
|
|
exceptions raised within the autoflush process.
|
||
|
|
|
||
|
|
:param context: an :class:`.ExceptionContext` object. See this
|
||
|
|
class for details on all available members.
|
||
|
|
|
||
|
|
.. versionadded:: 0.9.7 Added the
|
||
|
|
:meth:`_events.ConnectionEvents.handle_error` hook.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.1 The :meth:`.handle_error` event will now
|
||
|
|
receive all exceptions that inherit from ``BaseException``,
|
||
|
|
including ``SystemExit`` and ``KeyboardInterrupt``. The setting for
|
||
|
|
:attr:`.ExceptionContext.is_disconnect` is ``True`` in this case and
|
||
|
|
the default for
|
||
|
|
:attr:`.ExceptionContext.invalidate_pool_on_disconnect` is
|
||
|
|
``False``.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.0.0 The :meth:`.handle_error` event is now
|
||
|
|
invoked when an :class:`_engine.Engine` fails during the initial
|
||
|
|
call to :meth:`_engine.Engine.connect`, as well as when a
|
||
|
|
:class:`_engine.Connection` object encounters an error during a
|
||
|
|
reconnect operation.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.0.0 The :meth:`.handle_error` event is
|
||
|
|
not fired off when a dialect makes use of the
|
||
|
|
``skip_user_error_events`` execution option. This is used
|
||
|
|
by dialects which intend to catch SQLAlchemy-specific exceptions
|
||
|
|
within specific operations, such as when the MySQL dialect detects
|
||
|
|
a table not present within the ``has_table()`` dialect method.
|
||
|
|
Prior to 1.0.0, code which implements :meth:`.handle_error` needs
|
||
|
|
to ensure that exceptions thrown in these scenarios are re-raised
|
||
|
|
without modification.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def engine_connect(self, conn, branch):
|
||
|
|
"""Intercept the creation of a new :class:`_engine.Connection`.
|
||
|
|
|
||
|
|
This event is called typically as the direct result of calling
|
||
|
|
the :meth:`_engine.Engine.connect` method.
|
||
|
|
|
||
|
|
It differs from the :meth:`_events.PoolEvents.connect` method, which
|
||
|
|
refers to the actual connection to a database at the DBAPI level;
|
||
|
|
a DBAPI connection may be pooled and reused for many operations.
|
||
|
|
In contrast, this event refers only to the production of a higher level
|
||
|
|
:class:`_engine.Connection` wrapper around such a DBAPI connection.
|
||
|
|
|
||
|
|
It also differs from the :meth:`_events.PoolEvents.checkout` event
|
||
|
|
in that it is specific to the :class:`_engine.Connection` object,
|
||
|
|
not the
|
||
|
|
DBAPI connection that :meth:`_events.PoolEvents.checkout` deals with,
|
||
|
|
although
|
||
|
|
this DBAPI connection is available here via the
|
||
|
|
:attr:`_engine.Connection.connection` attribute.
|
||
|
|
But note there can in fact
|
||
|
|
be multiple :meth:`_events.PoolEvents.checkout`
|
||
|
|
events within the lifespan
|
||
|
|
of a single :class:`_engine.Connection` object, if that
|
||
|
|
:class:`_engine.Connection`
|
||
|
|
is invalidated and re-established. There can also be multiple
|
||
|
|
:class:`_engine.Connection`
|
||
|
|
objects generated for the same already-checked-out
|
||
|
|
DBAPI connection, in the case that a "branch" of a
|
||
|
|
:class:`_engine.Connection`
|
||
|
|
is produced.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object.
|
||
|
|
:param branch: if True, this is a "branch" of an existing
|
||
|
|
:class:`_engine.Connection`. A branch is generated within the course
|
||
|
|
of a statement execution to invoke supplemental statements, most
|
||
|
|
typically to pre-execute a SELECT of a default value for the purposes
|
||
|
|
of an INSERT statement.
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:meth:`_events.PoolEvents.checkout`
|
||
|
|
the lower-level pool checkout event
|
||
|
|
for an individual DBAPI connection
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def set_connection_execution_options(self, conn, opts):
|
||
|
|
"""Intercept when the :meth:`_engine.Connection.execution_options`
|
||
|
|
method is called.
|
||
|
|
|
||
|
|
This method is called after the new :class:`_engine.Connection`
|
||
|
|
has been
|
||
|
|
produced, with the newly updated execution options collection, but
|
||
|
|
before the :class:`.Dialect` has acted upon any of those new options.
|
||
|
|
|
||
|
|
Note that this method is not called when a new
|
||
|
|
:class:`_engine.Connection`
|
||
|
|
is produced which is inheriting execution options from its parent
|
||
|
|
:class:`_engine.Engine`; to intercept this condition, use the
|
||
|
|
:meth:`_events.ConnectionEvents.engine_connect` event.
|
||
|
|
|
||
|
|
:param conn: The newly copied :class:`_engine.Connection` object
|
||
|
|
|
||
|
|
:param opts: dictionary of options that were passed to the
|
||
|
|
:meth:`_engine.Connection.execution_options` method.
|
||
|
|
|
||
|
|
.. versionadded:: 0.9.0
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:meth:`_events.ConnectionEvents.set_engine_execution_options`
|
||
|
|
- event
|
||
|
|
which is called when :meth:`_engine.Engine.execution_options`
|
||
|
|
is called.
|
||
|
|
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def set_engine_execution_options(self, engine, opts):
|
||
|
|
"""Intercept when the :meth:`_engine.Engine.execution_options`
|
||
|
|
method is called.
|
||
|
|
|
||
|
|
The :meth:`_engine.Engine.execution_options` method produces a shallow
|
||
|
|
copy of the :class:`_engine.Engine` which stores the new options.
|
||
|
|
That new
|
||
|
|
:class:`_engine.Engine` is passed here.
|
||
|
|
A particular application of this
|
||
|
|
method is to add a :meth:`_events.ConnectionEvents.engine_connect`
|
||
|
|
event
|
||
|
|
handler to the given :class:`_engine.Engine`
|
||
|
|
which will perform some per-
|
||
|
|
:class:`_engine.Connection` task specific to these execution options.
|
||
|
|
|
||
|
|
:param conn: The newly copied :class:`_engine.Engine` object
|
||
|
|
|
||
|
|
:param opts: dictionary of options that were passed to the
|
||
|
|
:meth:`_engine.Connection.execution_options` method.
|
||
|
|
|
||
|
|
.. versionadded:: 0.9.0
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:meth:`_events.ConnectionEvents.set_connection_execution_options`
|
||
|
|
- event
|
||
|
|
which is called when :meth:`_engine.Connection.execution_options`
|
||
|
|
is
|
||
|
|
called.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def engine_disposed(self, engine):
|
||
|
|
"""Intercept when the :meth:`_engine.Engine.dispose` method is called.
|
||
|
|
|
||
|
|
The :meth:`_engine.Engine.dispose` method instructs the engine to
|
||
|
|
"dispose" of it's connection pool (e.g. :class:`_pool.Pool`), and
|
||
|
|
replaces it with a new one. Disposing of the old pool has the
|
||
|
|
effect that existing checked-in connections are closed. The new
|
||
|
|
pool does not establish any new connections until it is first used.
|
||
|
|
|
||
|
|
This event can be used to indicate that resources related to the
|
||
|
|
:class:`_engine.Engine` should also be cleaned up,
|
||
|
|
keeping in mind that the
|
||
|
|
:class:`_engine.Engine`
|
||
|
|
can still be used for new requests in which case
|
||
|
|
it re-acquires connection resources.
|
||
|
|
|
||
|
|
.. versionadded:: 1.0.5
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def begin(self, conn):
|
||
|
|
"""Intercept begin() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def rollback(self, conn):
|
||
|
|
"""Intercept rollback() events, as initiated by a
|
||
|
|
:class:`.Transaction`.
|
||
|
|
|
||
|
|
Note that the :class:`_pool.Pool` also "auto-rolls back"
|
||
|
|
a DBAPI connection upon checkin, if the ``reset_on_return``
|
||
|
|
flag is set to its default value of ``'rollback'``.
|
||
|
|
To intercept this
|
||
|
|
rollback, use the :meth:`_events.PoolEvents.reset` hook.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:meth:`_events.PoolEvents.reset`
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def commit(self, conn):
|
||
|
|
"""Intercept commit() events, as initiated by a
|
||
|
|
:class:`.Transaction`.
|
||
|
|
|
||
|
|
Note that the :class:`_pool.Pool` may also "auto-commit"
|
||
|
|
a DBAPI connection upon checkin, if the ``reset_on_return``
|
||
|
|
flag is set to the value ``'commit'``. To intercept this
|
||
|
|
commit, use the :meth:`_events.PoolEvents.reset` hook.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
"""
|
||
|
|
|
||
|
|
def savepoint(self, conn, name):
|
||
|
|
"""Intercept savepoint() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
:param name: specified name used for the savepoint.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def rollback_savepoint(self, conn, name, context):
|
||
|
|
"""Intercept rollback_savepoint() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
:param name: specified name used for the savepoint.
|
||
|
|
:param context: not used
|
||
|
|
|
||
|
|
"""
|
||
|
|
# TODO: deprecate "context"
|
||
|
|
|
||
|
|
def release_savepoint(self, conn, name, context):
|
||
|
|
"""Intercept release_savepoint() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
:param name: specified name used for the savepoint.
|
||
|
|
:param context: not used
|
||
|
|
|
||
|
|
"""
|
||
|
|
# TODO: deprecate "context"
|
||
|
|
|
||
|
|
def begin_twophase(self, conn, xid):
|
||
|
|
"""Intercept begin_twophase() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
:param xid: two-phase XID identifier
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def prepare_twophase(self, conn, xid):
|
||
|
|
"""Intercept prepare_twophase() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
:param xid: two-phase XID identifier
|
||
|
|
"""
|
||
|
|
|
||
|
|
def rollback_twophase(self, conn, xid, is_prepared):
|
||
|
|
"""Intercept rollback_twophase() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
:param xid: two-phase XID identifier
|
||
|
|
:param is_prepared: boolean, indicates if
|
||
|
|
:meth:`.TwoPhaseTransaction.prepare` was called.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def commit_twophase(self, conn, xid, is_prepared):
|
||
|
|
"""Intercept commit_twophase() events.
|
||
|
|
|
||
|
|
:param conn: :class:`_engine.Connection` object
|
||
|
|
:param xid: two-phase XID identifier
|
||
|
|
:param is_prepared: boolean, indicates if
|
||
|
|
:meth:`.TwoPhaseTransaction.prepare` was called.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
|
||
|
|
class DialectEvents(event.Events):
|
||
|
|
"""event interface for execution-replacement functions.
|
||
|
|
|
||
|
|
These events allow direct instrumentation and replacement
|
||
|
|
of key dialect functions which interact with the DBAPI.
|
||
|
|
|
||
|
|
.. note::
|
||
|
|
|
||
|
|
:class:`.DialectEvents` hooks should be considered **semi-public**
|
||
|
|
and experimental.
|
||
|
|
These hooks are not for general use and are only for those situations
|
||
|
|
where intricate re-statement of DBAPI mechanics must be injected onto
|
||
|
|
an existing dialect. For general-use statement-interception events,
|
||
|
|
please use the :class:`_events.ConnectionEvents` interface.
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:meth:`_events.ConnectionEvents.before_cursor_execute`
|
||
|
|
|
||
|
|
:meth:`_events.ConnectionEvents.before_execute`
|
||
|
|
|
||
|
|
:meth:`_events.ConnectionEvents.after_cursor_execute`
|
||
|
|
|
||
|
|
:meth:`_events.ConnectionEvents.after_execute`
|
||
|
|
|
||
|
|
|
||
|
|
.. versionadded:: 0.9.4
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
_target_class_doc = "SomeEngine"
|
||
|
|
_dispatch_target = Dialect
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def _listen(cls, event_key, retval=False):
|
||
|
|
target = event_key.dispatch_target
|
||
|
|
|
||
|
|
target._has_events = True
|
||
|
|
event_key.base_listen()
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def _accept_with(cls, target):
|
||
|
|
if isinstance(target, type):
|
||
|
|
if issubclass(target, Engine):
|
||
|
|
return Dialect
|
||
|
|
elif issubclass(target, Dialect):
|
||
|
|
return target
|
||
|
|
elif isinstance(target, Engine):
|
||
|
|
return target.dialect
|
||
|
|
elif isinstance(target, Dialect):
|
||
|
|
return target
|
||
|
|
elif hasattr(target, "dispatch") and hasattr(
|
||
|
|
target.dispatch._events, "_no_async_engine_events"
|
||
|
|
):
|
||
|
|
target.dispatch._events._no_async_engine_events()
|
||
|
|
else:
|
||
|
|
return None
|
||
|
|
|
||
|
|
def do_connect(self, dialect, conn_rec, cargs, cparams):
|
||
|
|
"""Receive connection arguments before a connection is made.
|
||
|
|
|
||
|
|
This event is useful in that it allows the handler to manipulate the
|
||
|
|
cargs and/or cparams collections that control how the DBAPI
|
||
|
|
``connect()`` function will be called. ``cargs`` will always be a
|
||
|
|
Python list that can be mutated in-place, and ``cparams`` a Python
|
||
|
|
dictionary that may also be mutated::
|
||
|
|
|
||
|
|
e = create_engine("postgresql+psycopg2://user@host/dbname")
|
||
|
|
|
||
|
|
@event.listens_for(e, 'do_connect')
|
||
|
|
def receive_do_connect(dialect, conn_rec, cargs, cparams):
|
||
|
|
cparams["password"] = "some_password"
|
||
|
|
|
||
|
|
The event hook may also be used to override the call to ``connect()``
|
||
|
|
entirely, by returning a non-``None`` DBAPI connection object::
|
||
|
|
|
||
|
|
e = create_engine("postgresql+psycopg2://user@host/dbname")
|
||
|
|
|
||
|
|
@event.listens_for(e, 'do_connect')
|
||
|
|
def receive_do_connect(dialect, conn_rec, cargs, cparams):
|
||
|
|
return psycopg2.connect(*cargs, **cparams)
|
||
|
|
|
||
|
|
|
||
|
|
.. versionadded:: 1.0.3
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:ref:`custom_dbapi_args`
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def do_executemany(self, cursor, statement, parameters, context):
|
||
|
|
"""Receive a cursor to have executemany() called.
|
||
|
|
|
||
|
|
Return the value True to halt further events from invoking,
|
||
|
|
and to indicate that the cursor execution has already taken
|
||
|
|
place within the event handler.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def do_execute_no_params(self, cursor, statement, context):
|
||
|
|
"""Receive a cursor to have execute() with no parameters called.
|
||
|
|
|
||
|
|
Return the value True to halt further events from invoking,
|
||
|
|
and to indicate that the cursor execution has already taken
|
||
|
|
place within the event handler.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def do_execute(self, cursor, statement, parameters, context):
|
||
|
|
"""Receive a cursor to have execute() called.
|
||
|
|
|
||
|
|
Return the value True to halt further events from invoking,
|
||
|
|
and to indicate that the cursor execution has already taken
|
||
|
|
place within the event handler.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def do_setinputsizes(
|
||
|
|
self, inputsizes, cursor, statement, parameters, context
|
||
|
|
):
|
||
|
|
"""Receive the setinputsizes dictionary for possible modification.
|
||
|
|
|
||
|
|
This event is emitted in the case where the dialect makes use of the
|
||
|
|
DBAPI ``cursor.setinputsizes()`` method which passes information about
|
||
|
|
parameter binding for a particular statement. The given
|
||
|
|
``inputsizes`` dictionary will contain :class:`.BindParameter` objects
|
||
|
|
as keys, linked to DBAPI-specific type objects as values; for
|
||
|
|
parameters that are not bound, they are added to the dictionary with
|
||
|
|
``None`` as the value, which means the parameter will not be included
|
||
|
|
in the ultimate setinputsizes call. The event may be used to inspect
|
||
|
|
and/or log the datatypes that are being bound, as well as to modify the
|
||
|
|
dictionary in place. Parameters can be added, modified, or removed
|
||
|
|
from this dictionary. Callers will typically want to inspect the
|
||
|
|
:attr:`.BindParameter.type` attribute of the given bind objects in
|
||
|
|
order to make decisions about the DBAPI object.
|
||
|
|
|
||
|
|
After the event, the ``inputsizes`` dictionary is converted into
|
||
|
|
an appropriate datastructure to be passed to ``cursor.setinputsizes``;
|
||
|
|
either a list for a positional bound parameter execution style,
|
||
|
|
or a dictionary of string parameter keys to DBAPI type objects for
|
||
|
|
a named bound parameter execution style.
|
||
|
|
|
||
|
|
The setinputsizes hook overall is only used for dialects which include
|
||
|
|
the flag ``use_setinputsizes=True``. Dialects which use this
|
||
|
|
include cx_Oracle, pg8000, asyncpg, and pyodbc dialects.
|
||
|
|
|
||
|
|
.. note::
|
||
|
|
|
||
|
|
For use with pyodbc, the ``use_setinputsizes`` flag
|
||
|
|
must be passed to the dialect, e.g.::
|
||
|
|
|
||
|
|
create_engine("mssql+pyodbc://...", use_setinputsizes=True)
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:ref:`mssql_pyodbc_setinputsizes`
|
||
|
|
|
||
|
|
.. versionadded:: 1.2.9
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:ref:`cx_oracle_setinputsizes`
|
||
|
|
|
||
|
|
"""
|
||
|
|
pass
|