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Asked: 2026-06-17T07:39:28+00:00

I have a custom connection factory class (which inherits from psycopg2.extensions.connection ) that I

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I have a custom connection factory class (which inherits from psycopg2.extensions.connection) that I would like SQLAlchemy to use. From the create_engine() documentation,

**kwargs takes a wide variety of options which are routed towards their appropriate components. Arguments may be specific to the Engine,
the underlying Dialect, as well as the Pool. Specific dialects also
accept keyword arguments that are unique to that dialect.

When I try to specify a connection_factory parameter, like this:

engine = create_engine(dsn.engine_info(), connection_factory=ConnectionEx)

I get this traceback:

Traceback (most recent call last):   File "foo.py", line 8, in <module>
    from user import test_user   File "/vagrant/workspace/panel/panel/user.py", line 18, in <module>
    from panel.helpers import intval   File "/vagrant/workspace/panel/panel/__init__.py", line 51, in <module>
    import panel.views   File "/vagrant/workspace/panel/panel/views.py", line 13, in <module>
    from panel.api import api_functions   File "/vagrant/workspace/panel/panel/api/api_functions.py", line 27, in <module>
    from panel.targeting import SavedTargetSet   File "/vagrant/workspace/panel/panel/targeting.py", line 19, in <module>
    from panel.database import panelists_tbl, us_cities_tbl, income_buckets_tbl   File "/vagrant/workspace/panel/panel/database.py", line 39, in <module>
    engine = create_engine(dsn.engine_info(), connection_factory=ConnectionEx)   File "/home/vagrant/.virtualenvs/project/lib/python2.6/site-packages/sqlalchemy/engine/__init__.py", line 331, in create_engine
    return strategy.create(*args, **kwargs)   File "/home/vagrant/.virtualenvs/project/lib/python2.6/site-packages/sqlalchemy/engine/strategies.py", line 141, in create
    engineclass.__name__)) TypeError: Invalid argument(s) 'connection_factory' sent to create_engine(), using configuration PGDialect_psycopg2/QueuePool/Engine.  Please check that the keyword arguments are appropriate for this combination of components.
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1 Answer

  1. Editorial Team

    When the documentation is talking about “appropriate components,” its referring to the components of the SQLAlchemy API, rather than the various drivers. Since connection_factory is a parameter that needs to be sent to connect(), you should use the keyword connect_args in your call to create_engine (documentation also mentioned here). Thus:

    engine = create_engine(
    dsn.engine_info(), connect_args={'connection_factory': ConnectionEx})
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