How to get a cross-origin resource sharing (CORS) post request working

REQUEST:

 $.ajax({
            url: "http://localhost:8079/students/add/",
            type: "POST",
            crossDomain: true,
            data: JSON.stringify(somejson),
            dataType: "json",
            success: function (response) {
                var resp = JSON.parse(response)
                alert(resp.status);
            },
            error: function (xhr, status) {
                alert("error");
            }
        });

RESPONSE:

response = HttpResponse(json.dumps('{"status" : "success"}'))
response.__setitem__("Content-type", "application/json")
response.__setitem__("Access-Control-Allow-Origin", "*")

return response

Took me some time to find the solution.

In case your server response correctly and the request is the problem, you should add withCredentials: true to the xhrFields in the request:

$.ajax({
    url: url,
    type: method,
    // This is the important part
    xhrFields: {
        withCredentials: true
    },
    // This is the important part
    data: data,
    success: function (response) {
        // handle the response
    },
    error: function (xhr, status) {
        // handle errors
    }
});

Note: jQuery >= 1.5.1 is required

I solved my own problem when using google distance matrix API by setting my request header with Jquery ajax. take a look below.

var settings = {
          'cache': false,
          'dataType': "jsonp",
          "async": true,
          "crossDomain": true,
          "url": "https://maps.googleapis.com/maps/api/distancematrix/json?units=metric&origins=place_id:"+me.originPlaceId+"&destinations=place_id:"+me.destinationPlaceId+"&region=ng&units=metric&key=mykey",
          "method": "GET",
          "headers": {
              "accept": "application/json",
              "Access-Control-Allow-Origin":"*"
          }
      }

      $.ajax(settings).done(function (response) {
          console.log(response);

      });

Note what i added at the settings
**

"headers": {
          "accept": "application/json",
          "Access-Control-Allow-Origin":"*"
      }

**
I hope this helps.

I finally stumbled upon this link "A CORS POST request works from plain javascript, but why not with jQuery?" that notes that jQuery 1.5.1 adds the

 Access-Control-Request-Headers: x-requested-with

header to all CORS requests. jQuery 1.5.2 does not do this. Also, according to the same question, setting a server response header of

Access-Control-Allow-Headers: *

does not allow the response to continue. You need to ensure the response header specifically includes the required headers. ie:

Access-Control-Allow-Headers: x-requested-with