87 lines
2.4 KiB
ReStructuredText
87 lines
2.4 KiB
ReStructuredText
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.. highlight:: ini
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Storing Config in DB
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====================
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We're getting ahead of ourselves a little here, if you're reading this manual
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straight through. But for reference sake this probably belongs here.
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Settings Table
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--------------
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If you already have a Rattail DB, then it has a table named ``setting`` which
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is designed to store config values. It's just a regular table so you can write
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settings via SQL if you like:
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.. code-block:: sql
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insert into setting (name, value) values ('rattail.app_title', 'Poser');
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update setting set value = 'Something Else' where name = 'rattail.app_title';
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Although the main reason for putting settings in the DB is usually so you can
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edit them via the web app.
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Telling App to Read Config from DB
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----------------------------------
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Well first of all we must assume that the DB connection itself is configured.
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More on that later but let's say you have this in place::
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[rattail.db]
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default.url = postgresql://user:password@localhost/poser
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Then you also must tell the Rattail config engine that a) it should read config
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values from the DB at all, but probably also b) it should *prefer* values from
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the DB over what was read from file. Do this within your config file::
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[rattail.config]
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usedb = true
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preferdb = true
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With this in place, when the app requests a config value, it will come from the
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DB if present, falling back to the file value if that exists.
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File vs. DB Setting Names
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-------------------------
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You may have noticed that the SQL examples above, and the examples used in
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:doc:`syntax` are really for the same 'app_title' setting, but there is a key
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difference in naming.
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So in a config file you might have this snippet to define a setting::
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[rattail]
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app_title = Poser
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But then that same setting is written in SQL as:
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.. code-block:: sql
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insert into setting (name, value) values ('rattail.app_title', 'Poser');
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In other words the "section" and "option" names from the config file, are
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joined together with a dot, for the DB setting name.
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When the app requests a config value, it must specify both a section and
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option. The config engine then will auto-join them as needed when doing DB
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lookups.
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.. code-block:: python
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config.get('rattail', 'app_title')
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Avoiding the DB
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---------------
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The app can request config from "file only" if it needs to. It just has to
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specify a flag when reading the value, for example:
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.. code-block:: python
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config.get('rattail', 'app_title', usedb=False)
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