Viewing file:  signals.py (2.2 KB) -rw-r--r--
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"""
Provide django-style hooks for model events.
"""
from peewee import Model as _Model
class Signal(object):
def __init__(self):
self._flush()
def connect(self, receiver, name=None, sender=None):
name = name or receiver.__name__
if name not in self._receivers:
self._receivers[name] = (receiver, sender)
self._receiver_list.append(name)
else:
raise ValueError('receiver named %s already connected' % name)
def disconnect(self, receiver=None, name=None):
if receiver:
name = receiver.__name__
if name:
del self._receivers[name]
self._receiver_list.remove(name)
else:
raise ValueError('a receiver or a name must be provided')
def __call__(self, name=None, sender=None):
def decorator(fn):
self.connect(fn, name, sender)
return fn
return decorator
def send(self, instance, *args, **kwargs):
sender = type(instance)
responses = []
for name in self._receiver_list:
r, s = self._receivers[name]
if s is None or isinstance(instance, s):
responses.append((r, r(sender, instance, *args, **kwargs)))
return responses
def _flush(self):
self._receivers = {}
self._receiver_list = []
pre_save = Signal()
post_save = Signal()
pre_delete = Signal()
post_delete = Signal()
pre_init = Signal()
post_init = Signal()
class Model(_Model):
def __init__(self, *args, **kwargs):
super(Model, self).__init__(*args, **kwargs)
pre_init.send(self)
def prepared(self):
super(Model, self).prepared()
post_init.send(self)
def save(self, *args, **kwargs):
pk_value = self._get_pk_value()
created = kwargs.get('force_insert', False) or not bool(pk_value)
pre_save.send(self, created=created)
ret = super(Model, self).save(*args, **kwargs)
post_save.send(self, created=created)
return ret
def delete_instance(self, *args, **kwargs):
pre_delete.send(self)
ret = super(Model, self).delete_instance(*args, **kwargs)
post_delete.send(self)
return ret
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