将 connection_factory 指定到 SQLAlchemy 的 create_engine()答案

【问题标题】：Specify the connection_factory to SQLAlchemy's create_engine()将 connection_factory 指定到 SQLAlchemy 的 create_engine()
【发布时间】：2012-12-25 07:19:27
【问题描述】：

我有一个我希望 SQLAlchemy 使用的自定义连接工厂类（继承自 psycopg2.extensions.connection）。来自create_engine() 文档，

**kwargs 采用多种选项，这些选项被路由到相应的组件。参数可能特定于引擎，底层方言，以及池。特定方言也接受该方言独有的关键字参数。

当我尝试指定 connection_factory 参数时，如下所示：

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

我得到了这个回溯：

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.

【问题讨论】：

标签： python postgresql sqlalchemy psycopg2

【解决方案1】：

当文档谈到“适当的组件”时，它指的是 SQLAlchemy API 的组件，而不是各种驱动程序。由于connection_factory 是需要发送到connect() 的参数，因此您应该在调用create_engine 时使用关键字connect_args（documentation 也提到了here）。因此：

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

【讨论】：