Signals

Restone comes with several Blinker signals. The signals can be used to pre-process and post-process most parts of the read, create, update cycle.

Resources using the SQLAlchemyManager hook into these signals.

Signal listeners can edit the item:

>>> @before_create.connect_via(ArticleResource)
... def on_before_create_article(sender, item):
...     item.author_id = current_user.id

Listeners may also raise exceptions:

>>> @before_create.connect_via(ArticleResource)
... def on_before_create_article(sender, item):
...     if not current_user.is_editor:
...         raise BadRequest()

The better way is:

>>> class ArticleResource:
...    def on_before_create(self,item):
...        if not current_user.is_editor:
...            raise BadRequest()

The complete list of signals:

class signals.before_create

Parameters:

• sender – item resource

• item – instance of item

class signals.after_create

Parameters:

• sender – item resource

• item – instance of item

class signals.before_update

Parameters:

• sender – item resource

• item – instance of item

• changes (dict) – dictionary of changes, already parsed

class signals.after_update

Parameters:

• sender – item resource

• item – instance of item

• changes (dict) – dictionary of changes, already parsed

class signals.before_delete

Parameters:

• sender – item resource

• item – instance of item

class signals.after_delete

Parameters:

• sender – item resource

• item – instance of item

class signals.before_relate

Parameters:

• sender – parent resource

• item – instance of parent item

• attribute – name of relationship to child

• child – instance of child item

class signals.after_relate

Parameters:

• sender – parent resource

• item – instance of parent item

• attribute – name of relationship to child

• child – instance of child item

class signals.before_remove

Parameters:

• sender – parent resource

• item – instance of parent item

• attribute – name of relationship to child

• child – instance of child item

class signals.after_remove

Parameters:

• sender – parent resource

• item – instance of parent item

• attribute – name of relationship to child

• child – instance of child item

Note

Relation-related signals are only used by Relation, They do not apply to relations created or removed by updating an item with Res or Many fields.