Support for PROTECT on foreign keys

Are there plans to support on_delete=django.db.models.PROTECT in the admin? Right now ProtectedError is not caught.

[spapas]

Unfortunately the solution @pySilver posted works only for pages (that have the before_delete_page hook). It isn’t applicable when deleting images, documents or whatever else that is used needs to be deleted.

What I propose instead is to use the following middleware:

class HandleProtectionErrorMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def process_exception(self, request, exception):
        from django.db.models.deletion import ProtectedError
        from django.contrib import messages
        from django.http import HttpResponseRedirect

        if isinstance(exception, ProtectedError):
            messages.error(
                request,
                "The object you are trying to delete is used somewhere. Please remove any usages and try again!.",
            )
            return HttpResponseRedirect(request.path)

        return None

    def __call__(self, request):
        response = self.get_response(request)
        return response

Just add it to the end of your MIDDLEWARE list. If a ProtectedError is thrown it will catch it and add a proper message to the view gracefully handling the excception. I think that this middleware needs to be a part of the wagtail default installation or at least mentioned somewhere in the docs so that people can use it if they want it.

[pySilver]

@spapas I just mean that as workaround this middleware is fine (which is great since there is nothing else available right now), but as part of wagtail it should be done on a lower level.