mongoengine/docs/guide/signals.rst

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.. _signals:
Signals
=======
.. versionadded:: 0.5
Signal support is provided by the excellent `blinker`_ library and
will gracefully fall back if it is not available.
The following document signals exist in MongoEngine and are pretty self explanatory:
* `mongoengine.signals.pre_init`
* `mongoengine.signals.post_init`
* `mongoengine.signals.pre_save`
* `mongoengine.signals.post_save`
* `mongoengine.signals.pre_delete`
* `mongoengine.signals.post_delete`
* `mongoengine.signals.pre_bulk_insert`
* `mongoengine.signals.post_bulk_insert`
Example usage::
from mongoengine import *
from mongoengine import signals
class Author(Document):
name = StringField()
def __unicode__(self):
return self.name
@classmethod
def pre_save(cls, sender, document, **kwargs):
logging.debug("Pre Save: %s" % document.name)
@classmethod
def post_save(cls, sender, document, **kwargs):
logging.debug("Post Save: %s" % document.name)
if 'created' in kwargs:
if kwargs['created']:
logging.debug("Created")
else:
logging.debug("Updated")
signals.pre_save.connect(Author.pre_save, sender=Author)
signals.post_save.connect(Author.post_save, sender=Author)
.. _blinker: http://pypi.python.org/pypi/blinker