无法从控制器JsonResult方法获得Ajax成功

Question

function GetSort() {
    var url = '@Url.Action("GetSort", "CatMaster")';        
    $.ajax({
        type: "POST",
        url: url,
        dataType: "json",
        data: null,
        success: function (data) {                
            restrctTrans = false;            
            $("#Order").data("kendoNumericTextBox").value(data.NxtSort);                
        },
        error: function (data) {
            alert('error');
        }
    });
}

This calls an controller method which returns JSON value:

public JsonResult GetSort()
{
    var response = _catMaster.GetNextSort();
    return Json(response.NxtSort, JsonRequestBehavior.AllowGet);
}

Problem is the ajax success and error function is not called. But controller returns a value. Value of response.NxtSort is 1

Answer 1

try this

[HttPost]
public JsonResult GetSort()
{
    var response = _catMaster.GetNextSort();
    return Json(response.NxtSort, JsonRequestBehavior.AllowGet);
} 

 $("#Order").data("kendoNumericTextBox").value(data);  

Replace this with above

 $("#Order").data("kendoNumericTextBox").value(data.NxtSort);  

Answer 2

"the ajax success and error function is not called. But controller returns a value."

This scenario is extremely unlikely to be true. If the controller is returning something, then one of those functions will run. The only way they wouldn't run is if the ajax call fails prior to actually executing, for some other reason. You would see the error displayed in your browser's Developer Tools.

To verify this, you can check your browser's network tab (in the Developer Tools, press F12 on most browsers) and watch for the ajax call to see the HTTP response returned to the browser. If it's "200" then "success" will definitely run. If it's anything else, "error" will run. You could put an "alert" command into start of the "success" function to prove that it runs.

Also check for any errors in your browser's Console as well. I predict that data.NxtSort will not exist in the JavaScript context, because as you mentioned, you only return a single integer value from the controller, not an object which could contain a property with that name. data in the "success" function will simply be an integer with the value 1 . This means almost certainly there's an "undefined" error happening and showing in the console when you try to access the non-existent nxtSort property.

This means that, contrary to your statement, "success" is called, but then it crashes without outputting anything.

Simply replacing

$("#Order").data("kendoNumericTextBox").value(data.NxtSort); 

with

 $("#Order").data("kendoNumericTextBox").value(data); 

should solve your problem.

In future if you learn to use your browser's Developer Tools to debug your code, you can avoid simple problems such as this. The tools in Chrome and Firefox in particular are extremely powerful and informative.