superset源码分析-视图函数

用过superset的人都知道，superset的视图函数继承flask-appbuilder的ModelView和BaseView。用过flask的人都知道，视图加入应用有2中方式，一种是route函数，一种是add_url_rule函数，可是在继承了BaseView的Superset类中，没有看到调用route或着add_url_rule函数来注册Superset类，但是Superset类的方法就可以被调用，原来在BaseView中，它把superset类中的带有@expose装饰器的方法生成蓝图，然后蓝图负责把方法注册到app中

 def create_blueprint(self, appbuilder,
                         endpoint=None,
                         static_folder=None):
        """
            Create Flask blueprint. You will generally not use it

            :param appbuilder:
               the AppBuilder object
            :param endpoint:
               endpoint override for this blueprint, will assume class name if not provided
            :param static_folder:
               the relative override for static folder, if omitted application will use the appbuilder static
        """
        # Store appbuilder instance
        self.appbuilder = appbuilder

        # If endpoint name is not provided, get it from the class name
        self.endpoint = endpoint or self.__class__.__name__

        if self.route_base is None:
            self.route_base = '/' + self.__class__.__name__.lower()

        self.static_folder = static_folder
        if not static_folder:
            # Create blueprint and register rules
            self.blueprint = Blueprint(self.endpoint, __name__,
                                       url_prefix=self.route_base,
                                       template_folder=self.template_folder)
        else:
            self.blueprint = Blueprint(self.endpoint, __name__,
                                       url_prefix=self.route_base,
                                       template_folder=self.template_folder,
                                       static_folder=static_folder)
        self._register_urls()
        return self.blueprint

    def _register_urls(self):
        for attr_name in dir(self):
            attr = getattr(self, attr_name)
            if hasattr(attr, '_urls'):
                for url, methods in attr._urls:
                    self.blueprint.add_url_rule(url,
                                                attr_name,
                                                attr,
                                                methods=methods)