Can modeladmin edit_handlers be bound to an instance before checking `form.is_valid()` on Create and Edit views?

This is not an issue, more of a feature request to add the ability to further customize form handling in the admin (mainly to support an InlineFormPanel for OneToOneFields & ForeignKeys).

Currently the edit_handler.bind_to_instance is not called before the ModelFormView subclasses (CreateView and EditView) call form.is_valid() for put & post requests.

This prevents using panels that may customize the form on a “per instance” basis (such as a which related object is chosen).

I currently have to use custom Create & Edit views like this:

class BoundFormMixin:
    """ The bound form lets edit handlers customize the form
    on a per instance basis.
    """

    def get_bound_form(self):
        edit_handler = self.get_edit_handler().bind_to_instance(
            instance=self.get_instance(),
            form=self.get_form(),
            request=self.request)
        return edit_handler.form


class CreateView(BaseCreateView, BoundFormMixin):

    @transaction.atomic
    def post(self, request, *args, **kwargs):
        form = self.get_bound_form()
        if form.is_valid():
            return self.form_valid(form)
        else:
            return self.form_invalid(form)


class EditView(BaseEditView, BoundFormMixin):

    @transaction.atomic
    def post(self, request, *args, **kwargs):
        form = self.get_bound_form()
        if form.is_valid():
            return self.form_valid(form)
        else:
            return self.form_invalid(form)

It would be nice if this were built in. I would also like to contribute an InlineFormPanel to support OneToOneFields and ForeignKeys (similar to a ChooserPanel)

[ababic]

@frmdstryr Ah, I see what you mean now. To be truly useful, the form/edit_handler binding does need to happen earlier on in the request cycle.

I agree, I think the most backwards-compatible way to do this would be to override get_form(), and have that method take care of the binding, as well as form instantiation.

We might also want to think about saving a reference to the fully-bound edit handler instance to a view attribute or something, so that it can simply be picked up again in get_context_data(), instead of having to recreate/bind everything there.

[frmdstryr]

Thanks!