Yellow, everyone. I just pushed some code to 0.9.x to let plugins do
schema maintenance -- that is, lets them add, delete or modify tables in
the database. I wanted to explain what's going.
There's a new library, lib/schema.php. It has a class, Schema. That's a
singleton (just one schema per site), so you get it using Schema::get().
It has a bunch of methods for examining the schema and altering tables
and columns. You can peek at it if you wish.
The most useful is ensureTable(). This takes a table name and an array
of column definitions, and tries to make sure that a) that table exists
and b) it has the structure you define. It will use CREATE TABLE and
ALTER TABLE as necessary to add the table and/or add, drop, or modify
columns.
There is a new event, 'CheckSchema'. Plugin developers can hook this
event to check the schema for your plugin at the "right" time. A typical
example:
function onCheckSchema() {
$schema = Schema::get();
$schema->ensureTable('person',
array(new ColumnDef('id', 'integer', null, false,
'PRI'),
new ColumnDef('name', 'varchar', 255),
new ColumnDef('picture', 'blob'),
new ColumnDef('age', 'integer', null, true,
null, 25)));
return true;
}
You can see the constructor params for ColumnDef in lib/schema.php.
There is also a new config parameter, $config['db']['schemacheck']. It
determines when the CheckSchema event fires. /By default/, it is set to
'runtime', which means that the schema check is run at every web hit.
That's obviously sub-optimal, but necessary for installations that can't
run command-line programs. The value can also be set to 'script', which
means that the event is only fired when you run scripts/checkschema.php.
This is obviously much better, and you should set this if you can (and
run the script whenever you upgrade StatusNet or install a new plugin).
When we have a Web-based plugin installer (post-0.9.x timeframe), we'll
probably have a new default, 'install', which would trigger that event
whenever a plugin was upgraded, installed, or uninstalled.
I hope that's clear enough.
-Evan
--
Evan Prodromou
CEO, StatusNet, Inc.
[email protected] - http://identi.ca/evan - +1-514-554-3826
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