text: # sqlalchemy/engine/events.py
  # Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
  # <see AUTHORS file>
  #
  # This module is part of SQLAlchemy and is released under
  # the MIT License: https://www.opensource.org/licenses/mit-license.php
  
  
  from .base import Engine
  from .interfaces import ConnectionEventsTarget
  from .interfaces import Dialect
  from .. import event
  from .. import exc
  
  
  class ConnectionEvents(event.Events):
      """Available events for
      :class:`_engine.Connection` and :class:`_engine.Engine`.
  
      The methods here define the name of an event as well as the names of
      members that are passed to listener functions.
  
      An event listener can be associated with any
      :class:`_engine.Connection` or :class:`_engine.Engine`
      class or instance, such as an :class:`_engine.Engine`, e.g.::
  
          from sqlalchemy import event, create_engine
  
          def before_cursor_execute(conn, cursor, statement, parameters, context,
                                                          executemany):
              log.info("Received statement: %s", statement)
  
          engine = create_engine('postgresql+psycopg2://scott:tiger@localhost/test')
          event.listen(engine, "before_cursor_execute", before_cursor_execute)
  
      or with a specific :class:`_engine.Connection`::
  
          with engine.begin() as conn:
              @event.listens_for(conn, 'before_cursor_execute')
              def before_cursor_execute(conn, cursor, statement, parameters,
                                              context, executemany):
                  log.info("Received statement: %s", statement)
  
      When the methods are called with a `statement` parameter, such as in
      :meth:`.after_cursor_execute` or :meth:`.before_cursor_execute`,
      the statement is the exact SQL string that was prepared for transmission
      to the DBAPI ``cursor`` in the connection's :class:`.Dialect`.
  
      The :meth:`.before_execute` and :meth:`.before_cursor_execute`
      events can also be established with the ``retval=True`` flag, which
      allows modification of the statement and parameters to be sent
      to the database.  The :meth:`.before_cursor_execute` event is
      particularly useful here to add ad-hoc string transformations, such
      as comments, to all executions::
  
          from sqlalchemy.engine import Engine
          from sqlalchemy import event
  
          @event.listens_for(Engine, "before_cursor_execute", retval=True)
          def comment_sql_calls(conn, cursor, statement, parameters,
                                              context, executemany):
              statement = statement + " -- some comment"
              return statement, parameters
  
      .. note:: :class:`_events.ConnectionEvents` can be established on any
         combination of :class:`_engine.Engine`, :class:`_engine.Connection`,
         as well
         as instances of each of those classes.  Events across all
         four scopes will fire off for a given instance of
         :class:`_engine.Connection`.  However, for performance reasons, the
         :class:`_engine.Connection` object determines at instantiation time
         whether or not its parent :class:`_engine.Engine` has event listeners
         established.   Event listeners added to the :class:`_engine.Engine`
         class or to an instance of :class:`_engine.Engine`
         *after* the instantiation
         of a dependent :class:`_engine.Connection` instance will usually
         *not* be available on that :class:`_engine.Connection` instance.
         The newly
         added listeners will instead take effect for
         :class:`_engine.Connection`
         instances created subsequent to those event listeners being
         established on the parent :class:`_engine.Engine` class or instance.
  
      :param retval=False: Applies to the :meth:`.before_execute` and
        :meth:`.before_cursor_execute` events only.  When True, the
        user-defined event function must have a return value, which
        is a tuple of parameters that replace the given statement
        and parameters.  See those methods for a description of
        specific return arguments.
  
      """  # noqa
  
      _target_class_doc = "SomeEngine"
      _dispatch_target = ConnectionEventsTarget
  
      @classmethod
      def _listen(cls, event_key, retval=False):
          target, identifier, fn = (
              event_key.dispatch_target,
              event_key.identifier,
              event_key._listen_fn,
          )
  
          target._has_events = True
  
          if not retval:
              if identifier == "before_execute":
                  orig_fn = fn
  
                  def wrap_before_execute(
                      conn, clauseelement, multiparams, params, execution_options
                  ):
                      orig_fn(
                          conn,
                          clauseelement,
                          multiparams,
                          params,
                          execution_options,
                      )
                      return clauseelement, multiparams, params
  
                  fn = wrap_before_execute
              elif identifier == "before_cursor_execute":
                  orig_fn = fn
  
                  def wrap_before_cursor_execute(
                      conn, cursor, statement, parameters, context, executemany
                  ):
                      orig_fn(
                          conn,
                          cursor,
                          statement,
                          parameters,
                          context,
                          executemany,
                      )
                      return statement, parameters
  
                  fn = wrap_before_cursor_execute
          elif retval and identifier not in (
              "before_execute",
              "before_cursor_execute",
              "handle_error",
          ):
              raise exc.ArgumentError(
                  "Only the 'before_execute', "
                  "'before_cursor_execute' and 'handle_error' engine "
                  "event listeners accept the 'retval=True' "
                  "argument."
              )
          event_key.with_wrapper(fn).base_listen()
  
      @event._legacy_signature(
          "1.4",
          ["conn", "clauseelement", "multiparams", "params"],
          lambda conn, clauseelement, multiparams, params, execution_options: (
              conn,
              clauseelement,
              multiparams,
              params,
          ),
      )
      def before_execute(
          self, conn, clauseelement, multiparams, params, execution_options
      ):
          """Intercept high level execute() events, receiving uncompiled
          SQL constructs and other objects prior to rendering into SQL.
  
          This event is good for debugging SQL compilation issues as well
          as early manipulation of the parameters being sent to the database,
          as the parameter lists will be in a consistent format here.
  
          This event can be optionally established with the ``retval=True``
          flag.  The ``clauseelement``, ``multiparams``, and ``params``
          arguments should be returned as a three-tuple in this case::
  
              @event.listens_for(Engine, "before_execute", retval=True)
              def before_execute(conn, clauseelement, multiparams, params):
                  # do something with clauseelement, multiparams, params
                  return clauseelement, multiparams, params
  
          :param conn: :class:`_engine.Connection` object
          :param clauseelement: SQL expression construct, :class:`.Compiled`
           instance, or string statement passed to
           :meth:`_engine.Connection.execute`.
          :param multiparams: Multiple parameter sets, a list of dictionaries.
          :param params: Single parameter set, a single dictionary.
          :param execution_options: dictionary of execution
           options passed along with the statement, if any.  This is a merge
           of all options that will be used, including those of the statement,
           the connection, and those passed in to the method itself for
           the 2.0 style of execution.
  
           .. versionadded: 1.4
  
          .. seealso::
  
              :meth:`.before_cursor_execute`
  
          """
  
      @event._legacy_signature(
          "1.4",
          ["conn", "clauseelement", "multiparams", "params", "result"],
          lambda conn, clauseelement, multiparams, params, execution_options, result: (  # noqa
              conn,
              clauseelement,
              multiparams,
              params,
              result,
          ),
      )
      def after_execute(
          self,
          conn,
          clauseelement,
          multiparams,
          params,
          execution_options,
          result,
      ):
          """Intercept high level execute() events after execute.
  
  
          :param conn: :class:`_engine.Connection` object
          :param clauseelement: SQL expression construct, :class:`.Compiled`
           instance, or string statement passed to
           :meth:`_engine.Connection.execute`.
          :param multiparams: Multiple parameter sets, a list of dictionaries.
          :param params: Single parameter set, a single dictionary.
          :param execution_options: dictionary of execution
           options passed along with the statement, if any.  This is a merge
           of all options that will be used, including those of the statement,
           the connection, and those passed in to the method itself for
           the 2.0 style of execution.
  
           .. versionadded: 1.4
  
          :param result: :class:`_engine.CursorResult` generated by the
           execution.
  
          """
  
      def before_cursor_execute(
          self, conn, cursor, statement, parameters, context, executemany
      ):
          """Intercept low-level cursor execute() events before execution,
          receiving the string SQL statement and DBAPI-specific parameter list to
          be invoked against a cursor.
  
          This event is a good choice for logging as well as late modifications
          to the SQL string.  It's less ideal for parameter modifications except
          for those which are specific to a target backend.
  
          This event can be optionally established with the ``retval=True``
          flag.  The ``statement`` and ``parameters`` arguments should be
          returned as a two-tuple in this case::
  
              @event.listens_for(Engine, "before_cursor_execute", retval=True)
              def before_cursor_execute(conn, cursor, statement,
                              parameters, context, executemany):
                  # do something with statement, parameters
                  return statement, parameters
  
          See the example at :class:`_events.ConnectionEvents`.
  
          :param conn: :class:`_engine.Connection` object
          :param cursor: DBAPI cursor object
          :param statement: string SQL statement, as to be passed to the DBAPI
          :param parameters: Dictionary, tuple, or list of parameters being
           passed to the ``execute()`` or ``executemany()`` method of the
           DBAPI ``cursor``.  In some cases may be ``None``.
          :param context: :class:`.ExecutionContext` object in use.  May
           be ``None``.
          :param executemany: boolean, if ``True``, this is an ``executemany()``
           call, if ``False``, this is an ``execute()`` call.
  
          .. seealso::
  
              :meth:`.before_execute`
  
              :meth:`.after_cursor_execute`
  
          """
  
      def after_cursor_execute(
          self, conn, cursor, statement, parameters, context, executemany
      ):
          """Intercept low-level cursor execute() events after execution.
  
          :param conn: :class:`_engine.Connection` object
          :param cursor: DBAPI cursor object.  Will have results pending
           if the statement was a SELECT, but these should not be consumed
           as they will be needed by the :class:`_engine.CursorResult`.
          :param statement: string SQL statement, as passed to the DBAPI
          :param parameters: Dictionary, tuple, or list of parameters being
           passed to the ``execute()`` or ``executemany()`` method of the
           DBAPI ``cursor``.  In some cases may be ``None``.
          :param context: :class:`.ExecutionContext` object in use.  May
           be ``None``.
          :param executemany: boolean, if ``True``, this is an ``executemany()``
           call, if ``False``, this is an ``execute()`` call.
  
          """
  
      def handle_error(self, exception_context):
          r"""Intercept all exceptions processed by the
          :class:`_engine.Connection`.
  
          This includes all exceptions emitted by the DBAPI as well as
          within SQLAlchemy's statement invocation process, including
          encoding errors and other statement validation errors.  Other areas
          in which the event is invoked include transaction begin and end,
          result row fetching, cursor creation.
  
          Note that :meth:`.handle_error` may support new kinds of exceptions
          and new calling scenarios at *any time*.  Code which uses this
          event must expect new calling patterns to be present in minor
          releases.
  
          To support the wide variety of members that correspond to an exception,
          as well as to allow extensibility of the event without backwards
          incompatibility, the sole argument received is an instance of
          :class:`.ExceptionContext`.   This object contains data members
          representing detail about the exception.
  
          Use cases supported by this hook include:
  
          * read-only, low-level exception handling for logging and
            debugging purposes
          * exception re-writing
          * Establishing or disabling whether a connection or the owning
            connection pool is invalidated or expired in response to a
            specific exception [1]_.
  
          The hook is called while the cursor from the failed operation
          (if any) is still open and accessible.   Special cleanup operations
          can be called on this cursor; SQLAlchemy will attempt to close
          this cursor subsequent to this hook being invoked.
  
          .. note::
  
              .. [1] The pool "pre_ping" handler enabled using the
                  :paramref:`_sa.create_engine.pool_pre_ping` parameter does
                  **not** consult this event before deciding if the "ping"
                  returned false, as opposed to receiving an unhandled error.
                  For this use case, the :ref:`legacy recipe based on
                  engine_connect() may be used
                  <pool_disconnects_pessimistic_custom>`.  A future API allow
                  more comprehensive customization of the "disconnect"
                  detection mechanism across all functions.
  
          A handler function has two options for replacing
          the SQLAlchemy-constructed exception into one that is user
          defined.   It can either raise this new exception directly, in
          which case all further event listeners are bypassed and the
          exception will be raised, after appropriate cleanup as taken
          place::
  
              @event.listens_for(Engine, "handle_error")
              def handle_exception(context):
                  if isinstance(context.original_exception,
                      psycopg2.OperationalError) and \
                      "failed" in str(context.original_exception):
                      raise MySpecialException("failed operation")
  
          .. warning::  Because the
             :meth:`_events.ConnectionEvents.handle_error`
             event specifically provides for exceptions to be re-thrown as
             the ultimate exception raised by the failed statement,
             **stack traces will be misleading** if the user-defined event
             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.
  
          """
  
      @event._legacy_signature(
          "2.0", ["conn", "branch"], converter=lambda conn: (conn, False)
      )
      def engine_connect(self, conn):
          """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.
  
          :param conn: :class:`_engine.Connection` object.
  
          .. 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
          else:
              return target
  
      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
  