Viewing file:  signals.py (2.46 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 _flush(self):
self._receivers = set()
self._receiver_list = []
def connect(self, receiver, name=None, sender=None):
name = name or receiver.__name__
key = (name, sender)
if key not in self._receivers:
self._receivers.add(key)
self._receiver_list.append((name, receiver, sender))
else:
raise ValueError('receiver named %s (for sender=%s) already '
'connected' % (name, sender or 'any'))
def disconnect(self, receiver=None, name=None, sender=None):
if receiver:
name = name or receiver.__name__
if not name:
raise ValueError('a receiver or a name must be provided')
key = (name, sender)
if key not in self._receivers:
raise ValueError('receiver named %s for sender=%s not found.' %
(name, sender or 'any'))
self._receivers.remove(key)
self._receiver_list = [(n, r, s) for n, r, s in self._receiver_list
if n != name and s != sender]
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 n, r, s in self._receiver_list:
if s is None or isinstance(instance, s):
responses.append((r, r(sender, instance, *args, **kwargs)))
return responses
pre_save = Signal()
post_save = Signal()
pre_delete = Signal()
post_delete = Signal()
pre_init = Signal()
class Model(_Model):
def __init__(self, *args, **kwargs):
super(Model, self).__init__(*args, **kwargs)
pre_init.send(self)
def save(self, *args, **kwargs):
pk_value = self._pk if self._meta.primary_key else True
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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