modelform: override clean method

Question

I have two questions concerning the clean method on a modelform. Here is my example:

class AddProfileForm(ModelForm):
        ...
        password = forms.CharField(max_length=30,widget=forms.PasswordInput(attrs={'class':'form2'}))
        password_verify = forms.CharField(max_length=30,widget=forms.PasswordInput(attrs={'class':'form2'}), label='Retype password')
        ...

        class Meta:
            model = UserModel
            fields=("username", "password", "password_verify", "first_name", "last_name", "date_of_birth", "biography", "contacts", )

        #called on validation of the form
        def clean(self):
            #run the standard clean method first
            cleaned_data=super(AddProfileForm, self).clean()
            password = cleaned_data.get("password")
            password_verify = cleaned_data.get("password_verify")

            #check if passwords are entered and match
            if password and password_verify and password==password_verify:
                print "pwd ok"
            else:
                raise forms.ValidationError("Passwords do not match!")

            #always return the cleaned data
            return cleaned_data

1. Should I always call the standard clean method?

   cleaned_data=super(AddProfileForm, self).clean()
   

2. Should I always return the cleaned_data variable?

   return cleaned_data
   

Giustino

Answer 1

For 1, Yes, if you want to make use of parent class's validators. See this explanation on the doc.

Warning

The ModelForm.clean() method sets a flag that makes the model validation step validate the uniqueness of model fields that are marked as unique, unique_together or unique_for_date|month|year.

If you would like to override the clean() method and maintain this validation, you must call the parent class’s clean() method.

For 2, yes, if data validates properly. Otherwise raise validation error.

Effrontery

1 / So if I don't call the parent class's clean method, the other fields won't be validated? In which case should this be useful ? (fields always must be validated, musn't they?) 2/ In my clean method, there can be a validation error but I return cleaned_data anyway! Is it a wrong way to do? – Giustino

@rom, Fields are validated in their own field_clean() method. clean() method is to validate any combination or multiple fields with values relating to one another. – Effrontery

Ok so if I remove super(AddProfileForm, self).clean() it still works, no? Or it won't check the unique_together constraints (for example)? – Giustino

@rom, please read the answer to find out when it shall be called. – Effrontery

Yes sorry, I just edited my previous comment, now I understand. What about the second point? (In my clean method, there can be a validation error but I return cleaned_data anyway! Is it a wrong way to do?) – Giustino

@rom, Either you return cleaned_data with removing invalid fields, setting up errors for fields or raise validation error. docs.djangoproject.com/en/dev/ref/forms/validation – Effrontery

let us continue this discussion in chat – Giustino

Can you use an example to show how the super function is called? ie: should I return it? Should I call it in the beginning of my code or the end? – Accumulate