state.py 文件源码

def reload_model(self, app_label, model_name):
        if 'apps' in self.__dict__:  # hasattr would cache the property
            try:
                old_model = self.apps.get_model(app_label, model_name)
            except LookupError:
                related_models = set()
            else:
                # Get all relations to and from the old model before reloading,
                # as _meta.apps may change
                related_models = get_related_models_recursive(old_model)

            # Get all outgoing references from the model to be rendered
            model_state = self.models[(app_label, model_name)]
            # Directly related models are the models pointed to by ForeignKeys,
            # OneToOneFields, and ManyToManyFields.
            direct_related_models = set()
            for name, field in model_state.fields:
                if field.is_relation:
                    if field.remote_field.model == RECURSIVE_RELATIONSHIP_CONSTANT:
                        continue
                    rel_app_label, rel_model_name = _get_app_label_and_model_name(field.related_model, app_label)
                    direct_related_models.add((rel_app_label, rel_model_name.lower()))

            # For all direct related models recursively get all related models.
            related_models.update(direct_related_models)
            for rel_app_label, rel_model_name in direct_related_models:
                try:
                    rel_model = self.apps.get_model(rel_app_label, rel_model_name)
                except LookupError:
                    pass
                else:
                    related_models.update(get_related_models_recursive(rel_model))

            # Include the model itself
            related_models.add((app_label, model_name))

            # Unregister all related models
            with self.apps.bulk_update():
                for rel_app_label, rel_model_name in related_models:
                    self.apps.unregister_model(rel_app_label, rel_model_name)

            states_to_be_rendered = []
            # Gather all models states of those models that will be rerendered.
            # This includes:
            # 1. All related models of unmigrated apps
            for model_state in self.apps.real_models:
                if (model_state.app_label, model_state.name_lower) in related_models:
                    states_to_be_rendered.append(model_state)

            # 2. All related models of migrated apps
            for rel_app_label, rel_model_name in related_models:
                try:
                    model_state = self.models[rel_app_label, rel_model_name]
                except KeyError:
                    pass
                else:
                    states_to_be_rendered.append(model_state)

            # Render all models
            self.apps.render_multiple(states_to_be_rendered)