form_business

after.py

class GFKFormBusiness(object):
    def value_from_object(self, instance, name):
        return getattr(instance, name)

    def save_form_data(self, instance, name, value):
        setattr(instance, name, value)


class TestForm(forms.ModelForm):
    test = autocomplete.QuerySetSequenceModelField(
        form_business=GFKFormBusiness,
        queryset=autocomplete.QuerySetSequence(
            Group.objects.all(),
            TestModel.objects.all(),
        ),
        required=False,
    )

    class Meta:
        model = TestModel
        fields = ('name', 'test')


class TestView(generic.UpdateView):
    model = TestModel
    form_class = TestForm
    template_name = 'form.html'

before.py

class TestForm(forms.ModelForm):
    test = autocomplete.QuerySetSequenceModelField(
        queryset=autocomplete.QuerySetSequence(
            Group.objects.all(),
            TestModel.objects.all(),
        ),
    )   

    class Meta:
        model = TestModel
        fields = ('name',)
        
        
class TestView(generic.UpdateView):
    model = TestModel
    form_class = TestForm
    template_name = 'form.html'

    def get_form_kwargs(self):
        kwargs = super(TestView, self).get_form_kwargs()

        # Would have been done by GenericForeignKey.value_for_object
        kwargs['initial'] = dict(test=self.object.test)

        return kwargs

    def form_valid(self, form):
        self.object = form.save(commit=False)

        # Would have been done by GenericForeignKey.save_form_data
        self.object.test = form.cleaned_data['test']

        self.object.save()
        return super(TestView, self).form_valid(form)

models.py

from django.contrib.contenttypes.fields import GenericForeignKey
from django.db import models
from django.utils.encoding import python_2_unicode_compatible


@python_2_unicode_compatible
class TestModel(models.Model):
    name = models.CharField(max_length=200)

    content_type = models.ForeignKey(
        'contenttypes.ContentType',
        null=True,
        blank=True,
        editable=False,
    )

    object_id = models.PositiveIntegerField(
        null=True,
        blank=True,
        editable=False,
    )

    test = GenericForeignKey('content_type', 'object_id')

    def __str__(self):
        return self.name