Method before_request

src/flask/sansio/scaffold.py:460–484

Register a function to run before each request. For example, this can be used to open a database connection, or to load the logged in user from the session. .. code-block:: python @app.before_request def load_user(): if "user_id" in

(self, f: T_before_request)

    @setupmethod
    def before_request(self, f: T_before_request) -> T_before_request:
        """Register a function to run before each request.

        For example, this can be used to open a database connection, or
        to load the logged in user from the session.

        .. code-block:: python

            @app.before_request
            def load_user():
                if "user_id" in session:
                    g.user = db.session.get(session["user_id"])

        The function will be called without any arguments. If it returns
        a non-``None`` value, the value is handled as if it was the
        return value from the view, and further request handling is
        stopped.

        This is available on both app and blueprint objects. When used on an app, this
        executes before every request. When used on a blueprint, this executes before
        every request that the blueprint handles. To register with a blueprint and
        execute before every request, use :meth:`.Blueprint.before_app_request`.
        """
        self.before_request_funcs.setdefault(None, []).append(f)
        return f

    @setupmethod
    def after_request(self, f: T_after_request) -> T_after_request: