def get_full_permission_string(self, perm):
        """
        Return full permission string (app_label.perm_model)
        """
        if not getattr(self, 'model', None):
            raise AttributeError("You need to use `add_permission_logic` to "
                                 "register the instance to the model class "
                                 "before calling this method.")
        app_label = self.model._meta.app_label
        model_name = self.model._meta.object_name.lower()
        return "%s.%s_%s" % (app_label, perm, model_name)
Return full permission string (app_label.perm_model)