Django form field required conditionally

Question

I'd like to have a field which is required conditionally based on setting a boolean value to True or False.

What should I return to set required =True if is_company is set to True?

class SignupFormExtra(SignupForm):
    is_company = fields.BooleanField(label=(u"Is company?"), 
                                     required=False)
    NIP = forms.PLNIPField(label=(u'NIP'), required=False)

    def clean(self):
        if self.cleaned_data.get('is_company', True):
            return ...?
        else:
            pass

Solution

Check the Chapter on Cleaning and validating fields that depend on each other in the documentation.

The example given in the documentation can be easily adapted to your scenario:

def clean(self):
    cleaned_data = super(SignupFormExtra, self).clean()
    is_company = cleaned_data.get("is_company")
    nip = cleaned_data.get("NIP")
    if is_company and not nip:
        raise forms.ValidationError("NIP is a required field.")
    return cleaned_data

Comments

[Seth]

The link @arie provided also covers how to associate the error with the field by replacing the raise statement with self._errors["NIP"] = self.error_class(["This is a required field."])

[Reaz Murshed]

@Seth thanks for the comment! That was really helpful!