events.py 文件源码

def before_execute(self, conn, clauseelement, multiparams, params):
        """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, conn, clauseelement, multiparams, params):
                # do something with clauseelement, multiparams, params
                return clauseelement, multiparams, params

        :param conn: :class:`.Connection` object
        :param clauseelement: SQL expression construct, :class:`.Compiled`
         instance, or string statement passed to :meth:`.Connection.execute`.
        :param multiparams: Multiple parameter sets, a list of dictionaries.
        :param params: Single parameter set, a single dictionary.

        See also:

        :meth:`.before_cursor_execute`

        """