7 examples of 'on_delete django' in Python

405
def post_delete(sender, instance, **kwargs):
406
    post(True, sender, instance, **kwargs)

199
def post_delete(self):
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    if getattr(settings, 'NEOMODEL_SIGNALS', True):
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        signals.post_delete.send(sender=self.__class__, instance=self)

208
def test_restrict_gfk_no_fast_delete(self):
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    delete_top = DeleteTop.objects.create()
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    generic_b1 = GenericB1.objects.create(generic_delete_top=delete_top)
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    generic_b2 = GenericB2.objects.create(generic_delete_top=delete_top)
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    GenericDeleteBottom.objects.create(generic_b1=generic_b1, generic_b2=generic_b2)
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    msg = (
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        "Cannot delete some instances of model 'GenericB1' because they "
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        "are referenced through a restricted foreign key: "
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        "'GenericDeleteBottom.generic_b1'."
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    )
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    with self.assertRaisesMessage(RestrictedError, msg):
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        generic_b1.delete()
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    self.assertTrue(DeleteTop.objects.exists())
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    self.assertTrue(GenericB1.objects.exists())
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    self.assertTrue(GenericB2.objects.exists())
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    self.assertTrue(GenericDeleteBottom.objects.exists())
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    # Object referenced also with CASCADE relationship can be deleted.
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    delete_top.delete()
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    self.assertFalse(DeleteTop.objects.exists())
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    self.assertFalse(GenericB1.objects.exists())
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    self.assertFalse(GenericB2.objects.exists())
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    self.assertFalse(GenericDeleteBottom.objects.exists())

298
def delete(self, *args, **kwargs):
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    fields_after = self.form.fields.filter(order__gte=self.order)
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    fields_after.update(order=models.F("order") - 1)
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    super(Field, self).delete(*args, **kwargs)

87
@receiver(post_delete)
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def on_post_delete(sender, **kwargs):
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    """Expire ultracache cache keys affected by this object
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    """
91
    if not invalidate:
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        return
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    if kwargs.get("raw", False):
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        return
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    if sender is MigrationRecorder.Migration:
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        return
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    if issubclass(sender, Model):
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        obj = kwargs["instance"]
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        if isinstance(obj, Model):
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            # get_for_model itself is cached
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            try:
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                ct = ContentType.objects.get_for_model(sender)
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            except RuntimeError:
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                # This happens when ultracache is being used by another product
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                # during a test run.
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                return
107
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            # Expire cache keys
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            key = "ucache-%s-%s" % (ct.id, obj.pk)
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            to_delete = cache.get(key, [])
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            if to_delete:
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                try:
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                    cache.delete_many(to_delete)
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                except NotImplementedError:
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                    for k in to_delete:
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                        cache.delete(k)
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            cache.delete(key)
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            # Invalidate paths in reverse caching proxy
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            key = "ucache-pth-%s-%s" % (ct.id, obj.pk)
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            if purger is not None:
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                for path in cache.get(key, []):
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                    purger(path)
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            cache.delete(key)

99
def delete(self, *args, **kwargs):
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    self._send_notify("delete")
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    return super().delete(*args, **kwargs)

417
def pre_delete_tablejoin(instance, sender, **kwargs):
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    """
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    Remove the existing join in the database
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    """
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    instance.remove_joins()