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
13824	ModelValidation ignores blank=True	anonymous	nobody	"Cheers,

I'm not quite sure if this is a feature or a bug, so sorry if i misunderstood this.

I am using a Model ""Foo"" that has a field like this:

{{{
#!python
[...]
class Foo(models.Model):
    uid = models.ForeignKey(UserProfile, blank=True)
[...]
}}}

Next, I'm using this Model in a Form (via !ModelForm):
{{{
#!python
class FooForm(ModelForm):

    class Meta:
        model = Foo
[...]
}}}

I expect Django to ignore the `uid` when calling `is_valid()`, as it's `blank` attribute is set `True` , but I get a !ValueError:
{{{
#!sh
ValueError at /foo/add/

Cannot assign None: ""Foo.uid"" does not allow null values.

Request Method: 	POST
Request URL: 	http://localhost:8000/de/foo/add/
Django Version: 	1.2.1
Exception Type: 	ValueError
Exception Value: 	

Cannot assign None: ""Foo.uid"" does not allow null values.

Exception Location: 	<cut>/lib/python2.6/site-packages/django/db/models/fields/related.py in __set__, line 314
}}}

This is since at the point where `is_valid()` is valled, uid is set to `None`, since it is not sent by the form but filled in my view (it's request.user.get_profile().user_id).

I looked for this in the Django docs, but didn't get a proper solution but using `full_clean()` which would need me to adapt the code & use try/except ."		closed	Documentation	1.2		duplicate			Unreviewed	0	0	0	0