jQuery Ajax error handling, show custom exception

Question

Is there some way I can show custom exception messages as an alert in my jQuery AJAX error message?

For example, if I want to throw an exception on the server side via Struts by throw new ApplicationException("User name already exists");, I want to catch this message ('user name already exists') in the jQuery AJAX error message.

jQuery("#save").click(function () {
  if (jQuery('#form').jVal()) {
    jQuery.ajax({
      type: "POST",
      url: "saveuser.do",
      dataType: "html",
      data: "userId=" + encodeURIComponent(trim(document.forms[0].userId.value)),
      success: function (response) {
        jQuery("#usergrid").trigger("reloadGrid");
        clear();
        alert("Details saved successfully!!!");
      },
      error: function (xhr, ajaxOptions, thrownError) {
        alert(xhr.status);
        alert(thrownError);
      }
    });
  }
});

On the second alert, where I alert the thrown error, I am getting undefined and the status code is 500.

I am not sure where I am going wrong. What can I do to fix this problem?

Answer 1

ServerSide:

     doPost(HttpServletRequest request, HttpServletResponse response){ 
            try{ //logic
            }catch(ApplicationException exception){ 
               response.setStatus(400);
               response.getWriter().write(exception.getMessage());
               //just added semicolon to end of line

           }
 }

ClientSide:

 jQuery.ajax({// just showing error property
           error: function(jqXHR,error, errorThrown) {  
               if(jqXHR.status&&jqXHR.status==400){
                    alert(jqXHR.responseText); 
               }else{
                   alert("Something went wrong");
               }
          }
    }); 

Generic Ajax Error Handling

If I need to do some generic error handling for all the ajax requests. I will set the ajaxError handler and display the error on a div named errorcontainer on the top of html content.

$("div#errorcontainer")
    .ajaxError(
        function(e, x, settings, exception) {
            var message;
            var statusErrorMap = {
                '400' : "Server understood the request, but request content was invalid.",
                '401' : "Unauthorized access.",
                '403' : "Forbidden resource can't be accessed.",
                '500' : "Internal server error.",
                '503' : "Service unavailable."
            };
            if (x.status) {
                message =statusErrorMap[x.status];
                                if(!message){
                                      message="Unknown Error \n.";
                                  }
            }else if(exception=='parsererror'){
                message="Error.\nParsing JSON Request failed.";
            }else if(exception=='timeout'){
                message="Request Time out.";
            }else if(exception=='abort'){
                message="Request was aborted by the server";
            }else {
                message="Unknown Error \n.";
            }
            $(this).css("display","inline");
            $(this).html(message);
                 });

Answer 2

Throw a new exception on server using:

Response.StatusCode = 500

Response.StatusDescription = ex.Message()

I believe that the StatusDescription is returned to the Ajax call...

Example:

        Try

            Dim file As String = Request.QueryString("file")

            If String.IsNullOrEmpty(file) Then Throw New Exception("File does not exist")

            Dim sTmpFolder As String = "Temp\" & Session.SessionID.ToString()

            sTmpFolder = IO.Path.Combine(Request.PhysicalApplicationPath(), sTmpFolder)

            file = IO.Path.Combine(sTmpFolder, file)

            If IO.File.Exists(file) Then

                IO.File.Delete(file)

            End If

        Catch ex As Exception

            Response.StatusCode = 500

            Response.StatusDescription = ex.Message()

        End Try

Answer 3

This is probably caused by the JSON field names not having quotation marks.

Change the JSON structure from:

{welcome:"Welcome"}

to:

{"welcome":"Welcome"}

Answer 4

$("#fmlogin").submit(function(){
   $("#fmlogin").ajaxError(function(event,xhr,settings,error){
       $("#loading").fadeOut('fast');       
       $("#showdata").fadeIn('slow');   
       $("#showdata").html('Error please, try again later or reload the Page. Reason: ' + xhr.status);
       setTimeout(function() {$("#showdata").fadeOut({"opacity":"0"})} , 5500 + 1000); // delays 1 sec after the previous one
    });
});

If there is any form is submit with validate

simply use the rest of the code

$("#fmlogin").validate({...

... ... });

Answer 5

First we need to set <serviceDebug includeExceptionDetailInFaults="True" /> in web.config:

<serviceBehaviors> 
 <behavior name=""> 
  <serviceMetadata httpGetEnabled="true" /> 
    **<serviceDebug includeExceptionDetailInFaults="true" />** 
 </behavior> 
</serviceBehaviors>

In addition to that at jquery level in error part you need to parse error response that contains exception like:

.error(function (response, q, t) { 
  var r = jQuery.parseJSON(response.responseText); 
}); 

Then using r.Message you can actully show exception text.

Check complete code: http://www.codegateway.com/2012/04/jquery-ajax-handle-exception-thrown-by.html

Answer 6

Controller:

public class ClientErrorHandler : FilterAttribute, IExceptionFilter
{
    public void OnException(ExceptionContext filterContext)
    {
        var response = filterContext.RequestContext.HttpContext.Response;
        response.Write(filterContext.Exception.Message);
        response.ContentType = MediaTypeNames.Text.Plain;
        filterContext.ExceptionHandled = true;
    }
}

[ClientErrorHandler]
public class SomeController : Controller
{
    [HttpPost]
    public ActionResult SomeAction()
    {
        throw new Exception("Error message");
    }
}

View script:

$.ajax({
    type: "post", url: "/SomeController/SomeAction",
    success: function (data, text) {
        //...
    },
    error: function (request, status, error) {
        alert(request.responseText);
    }
});