如何将url中的变量传递给python flask

我正在使用 angularjs 将数据传递到后端（python 烧瓶）

var currenttopic = "All";
    $http.post("/CA/"currenttopic,date).success(function(response){
                console.log(response);
            });

在后端，python 烧瓶代码类似于

@app.route('/CA/<topic>', methods=['POST'])
@login_required
def competitivepertopic(topic):
    if request.method == 'POST':
        print(topic)
        data = request.get_json()
        pass
    return json.dumps({'data': topic})

现在如何将 currenttopic 变量传递给后端？