Plata: Working Shop class with custom Contact model

gistfile1.py

class BaseCheckoutForm(forms.ModelForm):
    """
    Needs self.request
    """

    def clean(self):
        data = self.cleaned_data

        email = data.get('email')
        create_account = data.get('create_account')

        if email:
            users = list(User.objects.filter(email=email))

            if users:
                if self.request.user not in users:
                    if self.request.user.is_authenticated():
                        self._errors['email'] = self.error_class([
                            _('This e-mail address belongs to a different account.')])
                    else:
                        self._errors['email'] = self.error_class([
                            _('This e-mail address might belong to you, but we cannot know for sure because you are not authenticated yet.')])

        return data


class CustomShop(Shop):
    def checkout_form(self, request, order):
        class CheckoutForm(BaseCheckoutForm):
            class Meta:
                fields = ['email'] + ['billing_%s' % f for f in Contact.ADDRESS_FIELDS]
                model = self.order_model

            def __init__(self, *args, **kwargs):
                contact = kwargs.pop('contact')
                self.request = kwargs.pop('request')
                shop = kwargs.pop('shop')

                if contact:
                    initial = {}
                    for f in contact.ADDRESS_FIELDS:
                        initial['billing_%s' % f] = getattr(contact, f)
                        kwargs['initial'] = initial

                super(CheckoutForm, self).__init__(*args, **kwargs)

                if not contact:
                    self.fields['create_account'] = forms.BooleanField(
                        label=_('create account'),
                        required=False, initial=True)

        return CheckoutForm