I’ve encountered situations using Django’s ModelForm where I’ve needed the form to validate differently then the default behavior in various instances.
Here’s an example of how I changed all the fields from the default of not being required to all being required without much effort:

class AddressRequiredForm(forms.ModelForm):

   def __init__(self, *args, **kwargs):
       super(AddressForm, self).__init__(*args, **kwargs)
       for name, field in self.fields.iteritems():
           if name not in ['address2',]:
               field.required = True

   class Meta:
       model = Address

This is pretty simple, but it saved me a lot of time by not having to re-type each field name with a new set of properties.

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