FlexGet uses SQLAlchemy for database access. There are however some custom additions that developers should be aware of.
The plugin system tries to make each plugin as much separated as possible. When the need for schema migrations became too overwhelming the team evaluated few possibilities but none of them were able to version each plugin separately. Even the latest official tool from SQLAlchemy authors does not seem to make it easily possible.
Because this special requirement we had to make custom implementation for migrations.
The plugin needs only to use custom
SCHEMA_VER = 0 Base = schema.versioned_base('plugin_name_here', SCHEMA_VER)
This will automatically track all the declarative models plugin uses. When there are changes in the plugin database, increment the number and add migration code. This is done with decorated function in the following manner.
@schema.upgrade('series') def upgrade(ver, session): if ver==1: # upgrade actions ver = 2 return ver
The upgrade function can NOT use any declarative models. That will break sooner or later when models are evolving.
There are several helper functions available in
allow querying database reflectively. Use SQLAlchemy’s core expression to make alterations
to the table structure.
If the plugin accumulates data into database that should be cleaned at some point manager.db_cleanup event should be used. This will be automatically called every 7 days in non intrusive way.
@event('manager.db_cleanup') def db_cleanup(session): # cleanup actions here