How can I access the result of the response of HttpRequest in Dart?

Question

After many attempts to get the content of the response in HttpRequest, I failed completely to know or understand why I can't have what I want, and I must mention that I can log and manipulate the response only inside an onReadyStateChange (onLoad and onLoadEnd are giving me the same results!), but I really want that value outside the callback.

Here is the part of code that I'm stuck with

Map responsData;
req=new HttpRequest()
            ..open(method,url)
            ..send(infojson);

req.onReadyStateChange.listen((ProgressEvent e){

  if (req.readyState == HttpRequest.DONE ){

    if(req.status == 200){

      responsData = {'data': req.responseText};
      print("data receaved: ${ req.responseText}");
      //will log {"data":mydata}

    }
    if(req.status == 0){

      responsData = {'data':'No server'};
      print(responsData );
      //will log {"data":No server}

    }  
  }
});
//anything here to get responsData won't work

Answer 1

You have to assign an onLoad callback before you call send. I'm not sure what you mean with only inside an onReadyStateChange. Maybe you want to assign the responseText to a variable outside the the callback.

Create a method:

Future<String> send(String method, String url, String infojson) {
  var completer = new Completer<String>();
  // var result;
  req=new HttpRequest()
        ..open(method,url)
        ..onLoad.listen((event) {
          //print('Request complete ${event.target.reponseText}'))
          // result = event.target.responseText;
          completer.complete(event.target.responseText);
        })
        ..send(infojson);
  return completer.future;
}

and call this method like

var result;
send(method, url).then(
  (e) {
    // result = e;
    print('Request complete ${e}'));
  });