On Mar 21, 8:00 pm, "A. Kong" <anthony.hw.k...@gmail.com> wrote:
> Hi, all,
>
> I am still encountering some problem with JsonpRequestBuilder. I hope
> anyone may point out what's why with my code.
>
> Basically I have a json server which emits the following data:
>
> ====
>
> [{'Article': {'title': 'Main test2010-03-17 19:21:54.865390'}},
> {'Article': {'title': 'Main test2010-03-17 19:25:19.773520'}}]
>
> ====
>
> On GWT front, I have
>
> ====
>
> public void onModuleLoad() {
>
> JsonpRequestBuilder requestBuilder = new
> JsonpRequestBuilder();
> requestBuilder.setCallbackParam("callback");
> requestBuilder.requestObject(SERVER_URL, new
> MyTestRequestCallback());
>
> }
>
> class MyTestRequestCallback implements
> AsyncCallback<JsArray<Article>> {
>
> @Override
> public void onFailure(Throwable caught) {
> Window.alert("Failed to send the message: " +
> caught.getMessage() +
> " " + caught.getStackTrace()[0].toString());
> }
>
> @Override
> public void onSuccess(JsArray<Article> result) {
> Window.alert(result.get(0).getTitle());
> }
>
> ====
>
> And here is my definition of Article class
>
> ====
> public class Article extends JavaScriptObject {
>
> protected Article() {};
>
> public final native String getTitle() /*-{ return this.title; }-*/;
>
> }
>
> ====
>
> The problem is: the result of "result.get(0).getTitle()" is always
> null.
>
> Setting the break point in the onSuccess() does not help much. The
> content of the valuable is a 'ref n' where n is a number (in the debug
> perspective of eclipse)
>
> My questions are
> 1) What is the likely cause of the failure of capturing 'title'? Any
> obvious error in my code?
Your code does the JS equivalent to "the_array[0].title" while given
the data snippet you gave it should be the_array[0].Article.title.
> 2) I tried to debug in firebug, but failed to locate where the parsing
> of json occurs. When I compiled the project, I used "output style" =
> detailed. When I search for ".title" i could not find anything.
> Shouldn't the native code be captured in the generated gwt code
> intact?
There's no "JSON parsing" with "JSON-P" as it's just JavaScript, not
JSON at all. IMO, you should find ".title" but maybe it has been
rewritten as the_obj["title"], with the String "interned" in a
"global" variable. Search for ".alert" instead ;-)
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