Django unique, null and blank CharField giving 'already exists' error on Admin page

Question

I\'ve been getting the most weird error ever. I have a Person model

class Person(models.Model):
    user = models.OneToOneField(User, primary_key=True)
    f         


        

Answer 1

This is an old one but I had a similar issue just now and though I would provide an alternative solution.

I am in a situation where I need to be able to have a CharField with null=True, blank=True and unique=True. If I submit an empty string in the admin panel it will not submit because the blank string is not unique.

To fix this, I override the 'clean' function in the ModelForm, and in there I check if it's a blank string and return the result accordinly.

class MyModelChangeForm(forms.ModelForm):

    class Meta:
        model = models.MyModel
        fields = ['email', 'name', 'something_unique_or_null',]

    def clean_something_unique_or_null(self):
        if self.cleaned_data['something_unique_or_null'] == "":
            return None
        else:
            return self.cleaned_data['something_unique_or_null']

This fixed the problem for me without having to sacrifice the unique attribute on the model field.

Hope this helps.

EDIT: You need to change where I have put "something_unique_or_null" to the name of your field. For example "clean_twitter_id".