19.1.9. camcops_server.cc_modules.cc_config¶
Copyright (C) 2012-2018 Rudolf Cardinal (rudolf@pobox.com).
This file is part of CamCOPS.
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CamCOPS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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class
camcops_server.cc_modules.cc_config.
CamcopsConfig
(config_filename: str)[source]¶ Class representing the config.
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get_sqla_engine
() → sqlalchemy.engine.base.Engine[source]¶ I was previously misinterpreting the appropriate scope of an Engine. I thought: create one per request. But the Engine represents the connection pool. So if you create them all the time, you get e.g. a ‘Too many connections’ error.
“The appropriate scope is once per [database] URL per application, at the module level.”
https://groups.google.com/forum/#!topic/sqlalchemy/ZtCo2DsHhS4 https://stackoverflow.com/questions/8645250/how-to-close-sqlalchemy-connection-in-mysql
Now, our CamcopsConfig instance is cached, so there should be one of them overall. See get_config() below.
Therefore, making the engine a member of this class should do the trick, whilst avoiding global variables.
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