Flask 服务器从 JS rest 调用返回 400 错误代码

Question

I'm calling my Flask view function (API) via Javascript (FETCH).

I'm having success with the GET method, but when using the PATCH method I'm receiving a 400 error code (Failed to load resource: the server responded with a status of 400 (BAD REQUEST)).

I reviewed the url, seems ok and the ID is being passed as an integer, so no clue on why it's giving this error message.

This function (load_follow_link) is fetching via GET and updating my "Follow" to "Unfollow" tag (no errors here):

function load_follow_link(id) {
    apply_csrf_token();

    fetch(`/follow_unfollow/${id}`)
    .then(response => response.json())
    .then(data => {
        if (data.is_following)
            document.getElementById('follow-unfollow-btn').innerHTML = 'Unfollow';
        else 
            document.getElementById('follow-unfollow-btn').innerHTML = 'Follow';
        
        document.getElementById('followers-count').innerHTML = data.followers_count;
        document.getElementById('following-count').innerHTML = data.following_count;
    });
}

This is the PATCH function (follow_unfollow) triggering the error message. It is supposed to call the view function and update the DB:

function follow_unfollow(id) {
    apply_csrf_token();
    
    fetch(`/follow_unfollow/${id}`, {
        method: 'PATCH'
    })
    .then(() => {
        load_follow_link(id);
    });
}

view function (doesn't get executed when request method is PATCH)

@app.route('/follow_unfollow/<int:tutor_id>', methods=['GET','PATCH'])
@login_required
def follow_unfollow(tutor_id):
    """ GET: returns if user is following the tutor, followers and following total
        PUT: follow or unfollow
    """
    user = Users.query.get(current_user.id)
    try:
        tutor = Tutors.query.get(tutor_id)
    except NoResultFound:
        return JsonResponse({"error": "Tutor not registered"}, status=401)

    following_count = user.following_total()
    followers_count = tutor.followers_total()
    is_following = user.is_following(tutor)

    if request.method == 'GET':
        return jsonify(is_following=is_following, followers_count=followers_count,
            following_count=following_count)
    
    elif request.method == 'PATCH':
        if is_following:
            user.unfollow(tutor)
        else:
            user.follow(tutor)
        db.session.commit()
        return success.return_response(message='Successfully Completed', status=204)
    else:
        return jsonify(error="GET or PUT request required", status=400)

I appreciate the help

Answer 1

Could be you are not returning a valid response. Where is success defined in success.return_response ?

Why not just return jsonify(...) ?