Jquery Ajax Call,不会调用Success或Error

Question

可能重复:
如何从函数中返回AJAX调用的响应？

我正在使用Jquery Ajax来调用服务来更新值.

function ChangePurpose(Vid, PurId) {
        var Success = false;
        $.ajax({
            type: "POST",
            url: "CHService.asmx/SavePurpose",
            dataType: "text",
            data: JSON.stringify({ Vid: Vid, PurpId: PurId }),
            contentType: "application/json; charset=utf-8",
            success: function (data) {
                Success = true;//doesnt goes here
            },
            error: function (textStatus, errorThrown) {
                Success = false;//doesnt goes here
            }

        });
        //done after here
        return Success;
    }

和服务:

[WebMethod]
        public string SavePurpose(int Vid, int PurpId)
        {
            try 
            {
                CHData.UpdatePurpose(Vid, PurpId);
                //List<IDName> abc = new List<IDName>();
                //abc.Add(new IDName { Name=1, value="Success" });
                return "Success";

            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
        }

该服务正在从AJAX成功调用.价值也在变化.但是在服务之后,成功:或者错误:函数没有被调用,在这种情况下,应该已经调用了成功但是它不起作用.

我使用了firebug,发现成功或错误函数被跳过并直接进入 return Success;

似乎无法找到代码的问题.

提前致谢

更新: 添加async: false修复问题

Answer 1

将您的代码更改为

function ChangePurpose(Vid, PurId) {
        var Success = false;
        $.ajax({
            type: "POST",
            url: "CHService.asmx/SavePurpose",
            dataType: "text",
            async:false,
            data: JSON.stringify({ Vid: Vid, PurpId: PurId }),
            contentType: "application/json; charset=utf-8",
            success: function (data) {
                Success = true;//doesnt goes here
            },
            error: function (textStatus, errorThrown) {
                Success = false;//doesnt goes here
            }

        });
        //done after here
        return Success;
    } 

您只能从synchronous函数返回值.否则你将不得不做一个callback.

所以我刚加入async:false,你的ajax电话

更新:

jquery ajax调用默认是异步的.因此,当ajax加载完成时,将调用成功和错误函数.但是你的return语句将在ajax调用开始后执行.

一个更好的方法将是

     // callbackfn is the pointer to any function that needs to be called
     function ChangePurpose(Vid, PurId, callbackfn) {
        var Success = false;
        $.ajax({
            type: "POST",
            url: "CHService.asmx/SavePurpose",
            dataType: "text",
            data: JSON.stringify({ Vid: Vid, PurpId: PurId }),
            contentType: "application/json; charset=utf-8",
            success: function (data) {
                callbackfn(data)
            },
            error: function (textStatus, errorThrown) {
                callbackfn("Error getting the data")
            }

        });
     } 


     function Callback(data)
     {
        alert(data);
     }

并将ajax称为

 // Callback is the callback-function that needs to be called when asynchronous call is complete
 ChangePurpose(Vid, PurId, Callback);

Answer 2

尝试将ajax调用封装到函数中,并将async选项设置为false.请注意,自jQuery 1.8以来不推荐使用此选项.

function foo() {
    var myajax = $.ajax({
        type: "POST",
        url: "CHService.asmx/SavePurpose",
        dataType: "text",
        data: JSON.stringify({ Vid: Vid, PurpId: PurId }),
        contentType: "application/json; charset=utf-8",
        async: false, //add this
    });
    return myajax.responseText;
}

你也可以这样做:

$.ajax({
    type: "POST",
    url: "CHService.asmx/SavePurpose",
    dataType: "text",
    data: JSON.stringify({ Vid: Vid, PurpId: PurId }),
    contentType: "application/json; charset=utf-8",
    async: false, //add this
}).done(function ( data ) {
        Success = true;
}).fail(function ( data ) {
       Success = false;
});

您可以阅读有关jqXHR jQuery对象的更多信息