Signalling Support
******************

Connect to the following signals to get notified before and after
changes are committed to the database. These changes are only tracked
if "SQLALCHEMY_TRACK_MODIFICATIONS" is enabled in the config.

New in version 0.10.

Changed in version 2.1: "before_models_committed" is triggered
correctly.

Deprecated since version 2.1: This will be disabled by default in a
future version.

models_committed

   This signal is sent when changed models were committed to the
   database.

   The sender is the application that emitted the changes. The
   receiver is passed the "changes" parameter with a list of tuples in
   the form "(model instance, operation)".

   The operation is one of "'insert'", "'update'", and "'delete'".

before_models_committed

   This signal works exactly like "models_committed" but is emitted
   before the commit takes place.
