Django admin: exclude field on change form only

Question

If there a way to detect if information in a model is being added or changed.

If there is can this information be used to exclude fields.

Some pseudocode to

Answer 1

The approach below has the advantage of not overriding the object wide exclude property; instead it is reset based on each type of request

class SubSectionAdmin(admin.ModelAdmin):
    add_exclude = ('field1', 'field2')
    edit_exclude = ('field2',)

    def add_view(self, *args, **kwargs):
        self.exclude = getattr(self, 'add_exclude', ())
        return super(SubSectionAdmin, self).add_view(*args, **kwargs)

    def change_view(self, *args, **kwargs):
        self.exclude = getattr(self, 'edit_exclude', ())
        return super(SubSectionAdmin, self).change_view(*args, **kwargs)