Frustration in Parsing XML or JSON with GWT

Question

Hey everyone,

For the past couple of days, I have been trying to get GWT to interpret either a JSONValue or a string of XML that gets passed back from the server (using PHP).

I'm pretty frustrated, because I can't seem to get anything to work. For the XML, I have confirmed that the String passed from PHP to GWT is a correct XML string. However, when I try to parse the XML, I get a bunch of null errors.

With the JSON, I get the following from the PHP:

 Value: {"item":[{"ID":null, "Primary":null, "Secondary":null, "Date":null, "Region":null},{"ID":null, "Primary":null, "Secondary":null, "Date":null, "Region":null},{"ID":null, "Primary":null, "Secondary":null, "Date":null, "Region":null}]}

I have no idea why the values are NULL, but this is how the GWT looks for the JSON:

 public void onChange(Widget sender) {
   lb.setText("Date selected: " + calendar.getDate());
   SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
   String current = df.format(calendar.getDate());

 RequestBuilder builder = new RequestBuilder(RequestBuilder.POST, URL.encode("http://www.kbehr.com/calendar/view_duty.php"));

try {
  builder.sendRequest(current, new RequestCallback(){
    public void onError(Request request, Throwable exception) {
   requestFailed(exception);
    }

    public void onResponseReceived(Request request, Response response) {

     String responseText = response.getText();
        try {
          JSONValue jsonValue = JSONParser.parse(responseText);
          processJSON(jsonValue);
        } catch (Exception e) {
          Window.alert("Error: " + e);
        }

 }});
}catch (RequestException ex) {
  requestFailed(ex);
}    

 }});
   fp.add(calendar);
   fp.add(lb);   
 }

 public void processJSON(JSONValue messageXml) {

 vp.clear();
 vp.add(new Label("Value: " + messageXml));
 RootPanel.get("slot2").add(vp);

 }

Does anyone know what I am doing wrong with the JSON? I am doing json_encode($array) in the PHP, and I have no idea how to break it down in GWT.

Unfortunately, there aren't many examples online, either...

Thanks!

Answer 1

It looks like your first problem is server-side (PHP) and has nothing to do with GWT. Just going to your page (http://www.kbehr.com/calendar/view_duty.php) should return some kind of data, not a whole bunch of nulls (probably).

As for how to use the JSON parser in GWT, go here and start reading at "2. Manipulating JSON data in the client-side code"