Hi there.
I was working with proxies models and I found an odd behavior on a
QuerySet, and I ask here whether it should be documented.
Consider the following code:
from django.db import models
#from model_utils.managers import InheritanceManager
class Generic(models.Model):
pass # comment this pass on second test
#objects = InheritanceManager()
class Specific(Generic):
class Meta:
proxy = True
class SpecificA(Generic):
pass
Specific.objects.create()
SpecificA.objects.create()
print Generic.objects.all()
print Specific.objects.all()
print SpecificA.objects.all()
#print Generic.objects.all().select_subclasses()
Specific.objects.all().delete()
SpecificA.objects.all().delete()
The output is:
[<Generic: Generic object>, <Generic: Generic object>]
[<Specific: Specific object>, <Specific: Specific object>]
[<SpecificA: SpecificA object>]
Why there are two <Specific: Specific object> in the second list? I would
expect 1 instance (the database has 2 rows in Generic and one 1 row in
SpecificA).
Furthermore, I also realized that the InheritanceManager (from
django-model-utils<https://django-model-utils.readthedocs.org/en/latest/managers.html#inheritancemanager>
) is doing something odd on proxy models, which could be due to the
previous behavior. Uncommenting the three commented lines of the previous
code and commenting pass, the fourth print gives
[<Generic: Generic object>, <SpecificA: SpecificA object>]
I would expect <Specific: Specific object> instead of <Generic: Generic
object>.
I tested this behavior in Django 1.5.2 and 1.6 and the results are
equivalent.
Can someone double check this and confirm that this behavior is odd?
I searched in the documentation but I didn't found any reference that a
Query on the proxy model returns instances subclasses of the parent model,
instantiated as the proxy model itself. If this is the expected behavior,
shouldn't we document it? Nevertheless, it seems to me difficult to assume
that print Specific.objects.all()returns an instance created by
SpecificA.objects.create().
If this is not expected behavior, should I open a ticket with it?
Cheers,
Jorge
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