Trouble using POST with core-ajax-dart to send JSON data to a server REST API

Question

I am having trouble sending JSON data to my custom REST sever using core-ajax-dart. I can sucessfully send JSON data with the following

var host = window.location.hostname;
var data = JSON.encode(rows);
HttpRequest.request('http://$host:9999/services/directory/items/$instanceId', method: 'POST', mimeType: 'application/json', sendData: data).catchError((obj) {
  print(obj);
}).then((HttpRequest val) {
  print('response: ${val.responseText}');
}, onError: (e) => print("error"));

but when I try and do the same thing with core-ajax-dart,

<core-ajax-dart id="ajax"
  response="{{ response }}"
  handleAs="json"></core-ajax-dart>

$['ajax']
  ..url="http://$host:9999/services/directory/items/$instanceId"
  ..method = 'POST'
  ..contentType = 'application/json'
  ..body = JSON.encode(rows)
  ..go()
  ;

it fails with

Failed to load resource: the server responded with a status of 405 (Method Not Allowed)

Can someone tell me what I'm doing wrong here, as as far as I can see the core-ajax-dart method should work as advertised?

CLARIFICATION: I'm already using CORS, and the first HttpRequest.request works fine, just not when trying to POST using core-ajax-dart

Answer 1

Seems you need to set CORS headers on the server.

see
- Client in DART comunicate with server in PHP: access control allow origin headers missing
- problems with dart-server/angulardart and CORS
- CORS with Dart, how do I get it to work?