ajax Spring liferay - ajax

Question

I'm using an architetture that has: AJAX, Liferay 6.2, Spring 4.3.18.RELEASE;
From AJAX i make a call to the backend, that pass throu liferay and reach my controller;
Now, I want to generete an exception in the controller in order to reach the the failure of the ajax call; I've googled a lot but I wasn't able to find the solution.
my controller:
#Controller("movemementCon")
#RequestMapping("VIEW")
public class movemementCon {
#ResourceMapping("getDis")
#ResponseBody
public ResponseEntity<BenException> getImp(ResourceRequest request, ResourceResponse response, Model model) throws BenException{
return new ResponseEntity<BenException>(HttpStatus.NOT_ACCEPTABLE);
}
But when i reach the code in javascript (the AJAX call) it ignored definitively that I've throw an exception;
The desidered behaviur is that i force to go to the error statment in the AJAX call.

Answer 1

In web browser you can't catch java errors on client side, because client doesn't know anything about backend. You have to catch that error in spring controller method and then return ResponseEntity with some status, response body, custom response headers, so you can notify client that something went wrong and handle it correctly there.
#Controller("movemementCon")
#RequestMapping("VIEW")
public class movemementCon {
#ResourceMapping("getDis")
#ResponseBody
public ResponseEntity<SomeClass> getImp(ResourceRequest request, ResourceResponse response, Model model) {
try{
deleteFromDatabase(model);
} catch(BenException e) {
return new ResponseEntity<>(HttpStatus.NOT_ACCEPTABLE);
}
return new ResponseEntity<>(HttpStatus.OK);
}
}
Then in your JS read the status and execute right action.