passing initial data to a formset, doesn't show data_changed as true / does not save data

Not sure if this is a deeper problem with Django ModelForms, or just this package.

If I have a ModelFormSetView, to add Persons objects to a Trip object. I want to add some initial data to the forms, default names for each person, “Person 1”, “Person 2” etc.

class AddPersonsFormSetView(ModelFormSetView):
    model = Person
    template_name = 'AddPersons.html'
    extra = 1
    success_url = '/trip/%s/expense/add/'

     def get_formset_kwargs(self):
         kwargs = super(AddPersonsFormSetView, self).get_formset_kwargs()
         num_persons = self.kwargs['num_persons']

         ## inital data will give the name Person <increment> 
         initial = [ 
             { 'name' : "Person %s" % i , 'trip' : self.kwargs['trip_id'] }  for i in range( 1, int(num_persons)+ 1)
         ]

         kwargs.update({'initial': initial })
         return kwargs

Now if I change the values in the form, it saves correctly. If I leave the default values as they are, the PersonForm generated by the factory does not see the data_changed() as True, so doesn’t save anything.

I can work around this by creating the form, overriding the has_changed method, and specifying it in the get_factory_kwargs() method of the AddPersonFormSetView but this isn’t an obvious solution until you step through the code. It doesn’t not feel seem correct behaviour to ignore default values.

class PersonForm(ModelForm):
    class Meta:
        model=Person   

    def has_changed(self):
        """
        Overriding this, as the initial data passed to the form does not get noticed, 
        and so does not get saved, unless it actually changes
        """
        changed_data = super(ModelForm, self).has_changed()
        return bool(self.initial or changed_data)



class AddPersonsFormSetView(ModelFormSetView):
    ... 
    ... 
    def get_factory_kwargs(self):
        kwargs = super(AddPersonsFormSetView, self).get_factory_kwargs()
        kwargs['form'] = PersonForm
        return kwargs

[jonashaag]

Happened to me too. The correct way to fix this is to not pass the initial argument to the form in case we’re binding the form (POST).

[jonashaag]

Agreed