71 lines
2.8 KiB
Python
71 lines
2.8 KiB
Python
from collections import defaultdict
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from django.db.models.loading import get_model
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from django.dispatch import Signal
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from django.utils import six
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class_prepared = Signal(providing_args=["class"])
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class ModelSignal(Signal):
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"""
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Signal subclass that allows the sender to be lazily specified as a string
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of the `app_label.ModelName` form.
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"""
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def __init__(self, *args, **kwargs):
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super(ModelSignal, self).__init__(*args, **kwargs)
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self.unresolved_references = defaultdict(list)
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class_prepared.connect(self._resolve_references)
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def _resolve_references(self, sender, **kwargs):
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opts = sender._meta
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reference = (opts.app_label, opts.object_name)
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try:
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receivers = self.unresolved_references.pop(reference)
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except KeyError:
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pass
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else:
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for receiver, weak, dispatch_uid in receivers:
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super(ModelSignal, self).connect(
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receiver, sender=sender, weak=weak, dispatch_uid=dispatch_uid
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)
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def connect(self, receiver, sender=None, weak=True, dispatch_uid=None):
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if isinstance(sender, six.string_types):
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try:
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app_label, object_name = sender.split('.')
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except ValueError:
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raise ValueError(
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"Specified sender must either be a model or a "
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"model name of the 'app_label.ModelName' form."
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)
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sender = get_model(app_label, object_name, only_installed=False)
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if sender is None:
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reference = (app_label, object_name)
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self.unresolved_references[reference].append(
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(receiver, weak, dispatch_uid)
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)
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return
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super(ModelSignal, self).connect(
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receiver, sender=sender, weak=weak, dispatch_uid=dispatch_uid
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)
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pre_init = ModelSignal(providing_args=["instance", "args", "kwargs"], use_caching=True)
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post_init = ModelSignal(providing_args=["instance"], use_caching=True)
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pre_save = ModelSignal(providing_args=["instance", "raw", "using", "update_fields"],
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use_caching=True)
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post_save = ModelSignal(providing_args=["instance", "raw", "created", "using", "update_fields"], use_caching=True)
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pre_delete = ModelSignal(providing_args=["instance", "using"], use_caching=True)
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post_delete = ModelSignal(providing_args=["instance", "using"], use_caching=True)
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m2m_changed = ModelSignal(providing_args=["action", "instance", "reverse", "model", "pk_set", "using"], use_caching=True)
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pre_migrate = Signal(providing_args=["app", "create_models", "verbosity", "interactive", "db"])
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pre_syncdb = pre_migrate
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post_migrate = Signal(providing_args=["class", "app", "created_models", "verbosity", "interactive", "db"])
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post_syncdb = post_migrate
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