[Django] #26799: Model related signals' receiver could not receive its proxy models

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Jun 24, 2016, 3:14:58 AM6/24/16

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#26799: Model related signals' receiver could not receive its proxy models
-------------------------------------+-------------------------------------
Reporter: mapher87 | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: 1.9
(models, ORM) | Keywords: Model, Signal,
Severity: Normal | Generation
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
'''We have to connect the same receiver to its all proxy models one by
one'''

{{{#!python
class TestModel(models.Model):
field1 = models.CharField(max_length=64)
field2 = models.CharField(max_length=64)

class Meta:
db_table = 'app_label_test_model'

class ProxyTestModel(TestModel):
class Meta:
proxy = True

from django.db.models.signals import pre_save
def on_test_model_change(sender, instance, **kwargs):
if not instance.field1.startswith('*'):
instance.field1 = u'*' + instance.field1
pre_save.connect(on_test_model_change, sender=TestModel)
# pre_save.connect(on_test_model_change, sender=ProxyTestModel)

>>> t = TestModel()
>>> t.save()
>>> t.field1
u'*'
>>> pt = ProxyTestModel()
>>> pt.save()
>>> pt.field1
u''
}}}

Otherwise, we should consider to split one Model to manage it more
conveniently and safely.
As there is an attribute 'concrete_model' kept in Model's Option, could we
take the benefits of it?
{{{#!python
class RealTestModel1(models.Model):
field1 = models.CharField(max_length=64)
class Meta:
managed = False
db_table = 'app_label_test_model'

class RealTestModel2(models.Model):
field2 = models.CharField(max_length=64)
class Meta:
managed = False
db_table = 'app_label_test_model'
}}}
In my project, i hacked like this for more admin site features which could
be implemented in Model's generation process:
{{{#!python
from django.db.models.base import ModelBase
from django.dispatch import dispatcher
# for adapting to sub-models
_make_id = dispatcher._make_id
def _new_make_id(target):
if isinstance(target, ModelBase):
return id(getattr(target, '_concrete_model',
target._meta.concrete_model))
return _make_id(target)

dispatcher._make_id = _new_make_id

# ...

class ABSModelBase(ModelBase):
'''
Abstract Meta-Class to make new model performs as concrete model
'''

_concrete_model = ModelBase

def __subclasscheck__(cls, subclass):
return issubclass(subclass, cls._concrete_model)

def __instancecheck__(cls, instance):
return isinstance(instance, cls._concrete_model)

# ...
# create new class
new_class = ABSModelBase.__new__(
ABSModelBase, name, tuple(bases), attrs,
)

# register new_class as subclass of concrete_model
new_class.__bases__ = (concrete_meta.model, ) + new_class.__bases__
# register subclass and instance checking
new_class._concrete_model = concrete_meta.model
}}}

--
Ticket URL: <https://code.djangoproject.com/ticket/26799>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

Django

unread,

Jun 24, 2016, 9:24:30 AM6/24/16

to django-...@googlegroups.com

#26799: Model related signals' receiver could not receive its proxy models
-------------------------------------+-------------------------------------
Reporter: mapher87 | Owner: nobody

Type: New feature | Status: closed

Component: Database layer | Version: 1.9
(models, ORM) |

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by timgraham):

* status: new => closed
* needs_better_patch: => 0
* resolution: => duplicate
* needs_tests: => 0
* needs_docs: => 0