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Classe « Dialect »

Méthode sqlalchemy.Dialect.on_connect

Signature de la méthode on_connect

def on_connect(self) -> 'Optional[Callable[[Any], Any]]' 

Description

help(Dialect.on_connect)

return a callable which sets up a newly created DBAPI connection.

The callable should accept a single argument "conn" which is the
DBAPI connection itself.  The inner callable has no
return value.

E.g.::

    class MyDialect(default.DefaultDialect):
        # ...

        def on_connect(self):
            def do_on_connect(connection):
                connection.execute("SET SPECIAL FLAGS etc")

            return do_on_connect

This is used to set dialect-wide per-connection options such as
isolation modes, Unicode modes, etc.

The "do_on_connect" callable is invoked by using the
:meth:`_events.PoolEvents.connect` event
hook, then unwrapping the DBAPI connection and passing it into the
callable.

.. versionchanged:: 1.4 the on_connect hook is no longer called twice
   for the first connection of a dialect.  The on_connect hook is still
   called before the :meth:`_engine.Dialect.initialize` method however.

.. versionchanged:: 1.4.3 the on_connect hook is invoked from a new
   method on_connect_url that passes the URL that was used to create
   the connect args.   Dialects can implement on_connect_url instead
   of on_connect if they need the URL object that was used for the
   connection in order to get additional context.

If None is returned, no event listener is generated.

:return: a callable that accepts a single DBAPI connection as an
 argument, or None.

.. seealso::

    :meth:`.Dialect.connect` - allows the DBAPI ``connect()`` sequence
    itself to be controlled.

    :meth:`.Dialect.on_connect_url` - supersedes
    :meth:`.Dialect.on_connect` to also receive the
    :class:`_engine.URL` object in context.

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