ModelValidation ignores blank=True

[anonymous]

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:

[...]
class Foo(models.Model):
    uid = models.ForeignKey(UserProfile, blank=True)
[...]

Next, I'm using this Model in a Form (via ModelForm):

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:

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 .

[Karen Tracey]

You need both blank=True and null=True. The first allows blanks to be submitted as valid form values, the second allows nulls to be stored in the database field. See: ​http://docs.djangoproject.com/en/dev/ref/models/fields/#null

[R3dFox]

Hm, but I do not want the field to be allowed to store NULL ?

[R3dFox]

Further, uid_id may never be NULL due to django policies.

[Karen Tracey]

OK, if you actually want to support no entry in the form but require some value in the DB (which implies your code is somehow going to set the value to something after calling is_valid()) then this is a dupe of #13776.