Define a Custom Form for use in Django's ModelAdmin Add View

I'm trying to expose a Django model in admin using the ModelAdmin class. ModelAdmin seems to assume you use the same form for add and change. I'd like the add_view to use a simplified form that only lists a handful of required fields. After submission, it'll redirect to the change_view and use ModelForm's default form to render nearly all fields.

What's the easiest way to do this? I've inspected the code, but I don't see a clear way. ModelAdmin tends to refer to a single self.form reference in both the add_view and change_view. I'm thinking of overriding add_view(), but I don't want to reimplement all the code. It might be more efficient to overr开发者_StackOverflowide get_form(), but I don't see how to detect whether get_form() is being called during add_view or change_view.

get_form() is passed an obj parameter when called during change_view. Simply detect that return the new form/tweak parameters as needed.

For example:

class MyModelAdmin(admin.ModelAdmin):
    def get_form(self, request, obj=None, **kwargs):
        # hide every other field apart from url
        # if we are adding
        if obj is None:
            kwargs['fields'] = ['url']
        return super(MyModelAdmin, self).get_form(request, obj, **kwargs)

Will force the form to only display the "url" field when adding and everything else otherwise.