How does one use a custom widget with a generic UpdateView without having to redefine the entire form?

Question

I have a model with a ManyToMany relation that I would like to update with a CheckBoxSelectMultiple widget while everything else uses the default generic form, but when I redefi

Answer 1

Here's a mixin that allows you to define a widgets dictionary and still respects the fields list:

from django.forms.models import modelform_factory

class ModelFormWidgetMixin(object):
    def get_form_class(self):
        return modelform_factory(self.model, fields=self.fields, widgets=self.widgets)

It can be used with CreateView, UpdateView, etc. For example:

class KundleUpdate(ModelFormWidgetMixin, UpdateView):
    model = Kunde
    widgets = {
        'unternehmenstyp': CheckboxSelectMultiple,
    }

Answer 2

Try this, with class Meta:

from django.forms.widgets import CheckboxSelectMultiple
from django.forms import ModelMultipleChoiceField,ModelForm

from kunden.models import Kunde, Unternehmenstyp

class KundeEditForm(ModelForm):
    class Meta: # model must be in the Meta class
        model = Kunde
    unternehmenstyp = ModelMultipleChoiceField(widget=CheckboxSelectMultiple,required=True, queryset=Unternehmenstyp.objects.all())

REF: https://docs.djangoproject.com/en/1.5/topics/forms/modelforms/#modelform

You can also use modelform factories if you only need to make a simple override:

from django.views.generic.edit import UpdateView
from django.forms.models import modelform_factory

from kunden.models import Kunde, Unternehmenstyp

class KundeUpdate(UpdateView):
    model = Kunde
    form_class =  modelform_factory(Kunde,
        widgets={"unternehmenstyp": CheckboxSelectMultiple })
    template_name = 'kunden/kunde_update.html'
    success_url = '/'

REF: https://docs.djangoproject.com/en/1.5/topics/forms/modelforms/#modelform-factory-function