def r_oauth_login(self):
        """
        Route for OAuth2 Login

        :param next next url
        :type str

        :return: Redirects to OAuth Provider Login URL
        """
        session['next'] = request.args.get('next','')
        callback_url = self.authcallback
        if callback_url is None:
            callback_url = url_for('.r_oauth_authorized', _external=True)
        return self.authobj.authorize(callback=callback_url)
Route for OAuth2 Login

        :param next next url
        :type str

        :return: Redirects to OAuth Provider Login URL