ModelAdmin form_fields_exclude is ignored on models with a panels definition

Issue Summary

According to the docs and PR #3295, you should be able to add form_fields_exclude or get_form_fields_exclude on a ModelAdmin to exclude certain fields from rendering on the admin. When I tried it, it didn’t work. Upon further investigation, I found out that it has never actually worked. Issue #2759 is still open.

The issue is rooted in extract_panel_definitions_from_model_class function. When you have a model that has panels, it returns the panels as is, without filtering the excluded fields.

So a couple things that stand out to me:

1. Maybe mention in the docs that this doesn’t actually work
2. Find a way to make it work for all panel types

Steps to Reproduce

1. Create a ModelAdmin in wagtail_hooks.py
2. Set form_fields_exclude = ['some_field'] as a class attribute
3. Create a new instance of that model in the Wagtail admin
4. Look in confusion at the still present some_field

Workaround

I’m currently working around the issue by creating a custom CreateView for my ModelAdmins and overriding get_edit_handlers to remove panels I don’t want.

class PatchedCreateView(CreateView):

    def get_edit_handler_class(self):
        if hasattr(self.model, 'edit_handler'):
            edit_handler = self.model.edit_handler
        else:
            fields_to_exclude = self.model_admin.get_form_fields_exclude(
                request=self.request
            )
            panels = extract_panel_definitions_from_model_class(
                self.model,
                exclude=fields_to_exclude
            )

            # Filter out fields in fields_to_exclude
            panels = [
                panel for panel in panels
                if getattr(panel, 'field_name', None) not in fields_to_exclude
            ]

            edit_handler = ObjectList(panels)
        return edit_handler.bind_to_model(self.model)

Only problem is this doesn’t work for panels without field names. But in my particular case that’s okay.

Technical details

• Python version: 3.6.4
• Django version: 1.11.10
• Wagtail version: 1.13.1

[gasman]

Now reverted in e84b4a0 (master) / 6ccd665 (stable/2.1.x).

[lucasmoeskops]

Hi,

Thanks for the suggestions. I agree with the point from Matt and ababic that form_fields_exclude was not meant for this and am for reverting it. Optionally it could generate a warning maybe, saying that the form_fields_exclude option was ignored because of the panel definition.