Question

I’m thinking about creating a mixin form class so that I can add a common set of fields to a variety of otherwise very different forms. Just using it as a base class won’t work because I want to be able to use other forms as base classes like so:

class NoteFormMixin(object):
    note = forms.CharField()

class MainForm(forms.Form):
    name = forms.CharField()
    age = forms.IntegerField()

class SpecialForm(MainForm, NoteFormMixin):
    favorite_color = forms.CharField()

My only question is: how does this work? So far it looks like if I use a mixin, then it doesn’t recognize the fields set from that mixin:

>>> ff1 = SpecialForm()
>>> ff1.fields
{'name': <django.forms.fields.CharField object at 0x178d3110>, 'age': <django.forms.fields.IntegerField object at 0x178d3190>, 'favorite_color': <django.forms.fields.CharField object at 0x178d3210>}

Is this just something that can’t be done?

Answer 1

The issue is that your NoteFormMixin is deriving from object instead of forms.Form. You need to change it to be like so:

class NoteFormMixin(forms.Form):
    note = forms.CharField()