仅在实时服务器上解析来自JS AJAX请求的错误-Python GAE

Question

I have a number of AJAX requests (made with regular JS) that seem to be causing trouble when they make requests of my Python GAE back end. Here's an example:

newGame: function() {
    // Calls API to begin a new game, tells view to show placements
    var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
        if (xhttp.readyState === XMLHttpRequest.DONE) {
            // ... removed unnecessary code for this question
        }
    };
    var requestOjb = {"user_name": battleshipCtrl.user};
    xhttp.open('POST', requestPath + 'game', true);
    xhttp.send(JSON.stringify(requestOjb));
},

I am getting a code 400 with a Parse Error, but only on my deployed server. Everything works fine on the dev server. The error says the problem is with my back-end function "new_game", but does not specify a line where the error occurred. The endpoint function works correctly when I access it directly from the API explorer, so I figure the problem must be a result of the data sent from my JS file. Here's that function anyway:

@endpoints.method(request_message=NEW_GAME_REQUEST,
                  response_message=GameForm,
                  path='game',
                  name='new_game',
                  http_method='POST')
def new_game(self, request):
    """Creates new game"""
    user = User.query(User.name == request.user_name).get()
    # ... removed unnecessary code for this question
    return game.to_form('Good luck playing Battleship!')

The request message it's expecting takes the form of {'user_name': 'some_name'} and it appears, through console.log , that JS is sending it in the right format.

The log where the parse error comes up is interesting, because it shows a 200 code POST request, although it mentions the 400 error when I dive into that log.

I've double and triple checked that my code works on the dev server, and that I've got the exact same code deployed. I don't know where to look next to continue debugging this thing. Any help is appreciated.

Answer 1

Figured it out. I tried running the AJAX request with jQuery, and got a slightly different error message, which lead me to find that I had to set the request header, because it was causing the server to read the incoming data differently than it should have. The following AJAX request now works perfectly.

newGame: function() {
    // Calls API to begin a new game, tells view to show placements
    var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
        if (xhttp.readyState === XMLHttpRequest.DONE) {
            // ... removed unnecessary code for this question
        }
    };
    var requestOjb = {"user_name": battleshipCtrl.user};
    xhttp.open('POST', requestPath + 'game', true);
    xhttp.setRequestHeader('Content-type', 'application/json');
    xhttp.send(JSON.stringify(requestOjb));
},