对Controller中的JsonResult进行Ajax调用失败，并显示404错误，“未找到资源”

Question

Here is my ajax code in my "ManageUserRoles.cshtml":

//HIT THE DATABASE FOR USERNAME GIVING IT THIS USERNAME
function isUserValid(thisUser) {


    $.ajax({
        url: "/Roles/isUserValid/" + thisUser,
        type: 'POST',
        success: handleResultResponseUserName,
        error: function (xhr) { alert("Error..."); }
    });
}


//handles data back from ajax call
//RESET INPUT IF NO USER IF FOUND IN USER'S TABLE
function handleResultResponseUserName(ResponseObject) {

    if (ResponseObject == "no user with this number") {

        $('#frmGetRoles').find('input[name="UserName"]').val(null);

    }
    else {

        //DO NOTHING

    }

}

Here is my JsonResult in my RolesController:

[HttpPost]
[ValidateAntiForgeryToken]
public JsonResult isUserValid(string username)
{
    var name = string.Empty;

    var CheckUserExists = (from c in _db.AspNetUsers
                       where (c.UserName.Equals(username))
                       select c);


    var results = new JsonResult();

    if (CheckUserExists.Any())
    {

        name = CheckUserExists.First().UserName;

    }

    else
    {
        name = "no user with this name in database";

    }
    return Json(name, JsonRequestBehavior.DenyGet); 
}

I've got almost exact code working in a different application and I cut and pasted into a new one where I am trying to use it for Roles management.

The json reference is there, and in web.config. But when I put a breakpoint inside the JsonResult, it never stops there and an error is returned from the client javascript (404 resource not found). There is no other json stuff being used in this new app . . .yet.

I can hit f5 and it returns: http://localhost/StoreMasterSecure/Roles/ManageUserRoles which is the view that has the button that runs the ajax. It all gets to the ajax call and then nothing happens and Chrome Developer Tools console shows 404 error.

Even if I type in the URL the path, I get the resource not found 404 page: http://localhost/StoreMaster/Roles/isValidUser/xxxx@xxx.com

(isValidUser is the JsonResult in the controller, in same controller that ManageUserRoles ActionResult exists and works)

Answer 1

To ensure you url's are correctly generated, use the Url.Action() method and pass the data using the ajax data option. Change your ajax to

$.ajax({
    url: '@Url.Action("isUserValid", "Roles")', // change this
    data: { username: thisUser }, // add this
    type: 'POST',
    success: handleResultResponseUserName,
    error: function (xhr) { alert("Error..."); }
});

You also need to remove the [ValidateAntiForgeryToken] attibute from your controller method since you not passing the token.

Side note: MVC comes with a RemoteAttribute to handle this scenario. Refer How to: Implement Remote Validation in ASP.NET MVC which means you do not need your script.