Answers to each question:
1 Is there a way to access this callback from within GWT?
actually you cannot modify the callback itself, what you can do from GWT is to call any jquery method, thus you can unbind any previous added handler, and set yours.
//NOTE: not wrapping code in $entry() to make a clearer code.
private static native unbindForm() /*-{
// remove all jQuery handlers added previously to my form
$wnd.$("my_form_selector").off();
// add a new handler for the submit event
$wnd.$("my_form_selector").on("submit", function(event) {
event.preventDefault();
$wnd.$(this).post(url, ...).done(function(data) {
// Use JSNI to call a GWT method
@.com.example.MyClass.handleFormResponse(*)(data);
// NOTE: that you can use a star instead of having to write parameter
// types, when you only have one method signature in your class.
});
}
}-*/
// handle the form response in GWT
public static void handleFormResponse(String data) {
// handle form response in GWT
}
Another thing you can do with GWT, is to wrap your form
in a FormPanel
and use specific widget methods to set a handler and read the response. But I think this is not what you are asking for.
2 Is there a way to overwrite the JQuery send action
Yes, using JSNI to ask jQuery to unbind previously set events. See code in #1.
3 I need to get the response if the submitted form accessible to GWT
. You have to include in the jquery.post callback some code to call GWT static methods (you can use-non static as well but this way is easier) this is also JSNI. See code in #1.
4 Is there a way how I can achieve this with JSNI?
Of course, JSNI is the way to interact with handwritten javascript from GWT.
Aditional Notes:
GWT is designed to build RIA apps with very optimized js code. I know each one has their reasons for using external libraries, but adding 3party javascript to your app is against the main goals of gwt compiler
remove death code
andoptimize output
. If you like jquery like syntax and features for GWT I recomend to use gwtquery, which has been fully written in gwt, hence the compiler will include just the code you use.Writing JSNI is a source of mistakes difficult to handle in the debugger. So I recommend to use gwt-exporter to populate java methods/classes or gwtquery to call external javascript. See these post I wrote some time ago: Pass value from GWT to Javascript via JSNI and Calling GWT Java function from JavaScript