id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
21563	calling hasattr(model_instance, fieldname) raises DoesNotExist when False	monkut	nobody	"Using python 3.3 and django 1.6.

I've got a model (created from an AbstractBaseClass) and creating an instance of the model from some JSON, via serializers.deserialize(), then checking if the resulting parsed JSON model has the fields I'm expecting.  

(thinking about it now, this seems like the wrong thing to do, since it may be expected that the resulting Model instance has the field, but takes the default value? but anyway...)

When I check to see if the parsed instance.object has the given attribute, via hasattr(), it's raising DoesNotExist, instead of returning the expected False.

Again, maybe it's ok that it doesn't return False... but I don't think hasattr() should raise an exception.



{{{

from django.contrib.auth.models import User

class BaseTask(models.Model):
    assigned_to = models.ForiegnKey(User)

    class Meta:
        abstract = True

class Task(BaseTask):
    pass
}}}



{{{
Python 3.3.2 (v3.3.2:d047928ae3f6, May 16 2013, 00:06:53) [MSC v.1600 64 bit (AMD64)] on win32
Type ""help"", ""copyright"", ""credits"" or ""license"" for more information.
(InteractiveConsole)
>>> from myproject.myapp.models import Task
>>> from django.contrib.auth.models import User
>>> t = Task()
>>> hasattr(t, ""assigned_to"")
Traceback (most recent call last):
  File ""<console>"", line 1, in <module>
  File ""C:\Python33\lib\site-packages\django\db\models\fields\related.py"", line 314, in __get__
    ""%s has no %s."" % (self.field.model.__name__, self.field.name))
django.contrib.auth.models.DoesNotExist: Task has no assigned_to.
>>> u = User.objects.get(pk=1)
>>>
>>> t.assigned_to = u
>>> hasattr(t, ""assigned_to"")
True
>>>
}}}
"	Cleanup/optimization	closed	Database layer (models, ORM)	dev	Normal	fixed		Simon Charette	Ready for checkin	1	0	0	0	0	0