How to set initial values for a ModelForm when instance is also given

Question

It seems like if a ModelForm is given an instance, it ignores any values you provide for initial and instead sets it to the value of the instance -- even if tha

Answer 1

Figured this out after a little bit of googling.

You have to set the initial value before calling super.

So instead of looping through self.fields.keys(), I had to type out the list of fields that I wanted and looped through that instead:

class RegisterForm(forms.ModelForm):
    ... fields here ...
    initial_fields = ['first_name', 'last_name', ... ]

    def __init__(self, *args, **kwargs):
        ... other code ...
        self.person = kwargs.pop('person')
        for key in self.initial_fields:
            if hasattr(self.person, key):
                self.fields[k].initial = getattr(self.person, key)
        super(RegisterForm, self).__init__(*args, **kwargs)

@Daria rightly points out that you don't have self.fields before calling super. I'm pretty sure this will work:

class RegisterForm(forms.ModelForm):
    ... fields here ...
    initial_fields = ['first_name', 'last_name', ... ]

    def __init__(self, *args, **kwargs):
        ... other code ...
        initial = kwargs.pop('initial', {})
        self.person = kwargs.pop('person')
        for key in self.initial_fields:
            if hasattr(self.person, key):
                initial[key] = initial.get(key) or getattr(self.person, key)
        kwargs['initial'] = initial
        super(RegisterForm, self).__init__(*args, **kwargs)

In this version, we use the initial argument to pass the values in. It's also written so that if we already have a value in initial for that field, we don't overwrite it.