Ryan的blog

在撰寫$.ajax Call WebService時，常遇到需處理Exception，

若可以接收Exception的訊息，通知前端秀出訊息，就可以更好Debug或讓一些訊息可以給使用者觀看

在Js的部分:

<script src="../Scripts/json2.js" type="text/javascript"></script>

$.ajax({

        type: 'POST',

        url: 'WebService.asmx/GetJsonSend',

        data: JsonText,

           contentType: "application/json; charset=utf-8",

           dataType: 'json',                      

success: function (msg) {

                        var jsonData = eval("(" + msg.d + ")");

                        var gid =

                         "<table cellspacing='0' cellpadding='3  rules='cols' border='1' >" +

                        "<tr><th>ID</th><th>SN</th><th>Size</th></tr>";

                        $.each(jsonData, function (rec) {

                            gid += "<tr>";

                            gid += "<td>" + this.id + "</td><td>" + this.sn + "</td><td>" + this.size + "</td>";

                            gid += "</tr>";

                        });

                        gid += "</table>";

                        $(".panel").html(gid);

                    },

                    error: function (xhr, ajaxOptions, thrownError) {

                        //                        alert(xhr.statusText);

                        //                        alert(xhr.responseText);

                      //處理Exception訊息

                        var jsonData = JSON.parse(xhr.responseText);

                        $.each(jsonData, function (key, value) {

                            //接收Exception的訊息文字

                            if (key == 'Message') {

                                alert(value);

                            }

                        });

                    }

                }); //** ajax  End **//

WebService.cs部分

[WebMethod]

    public string GetJsonSend(List <string >  p_list ) {

        String Sql = "Select * From tCustomer Where fName='"+p_list[0]+"'";

        CSqlHelp l_Sh = new CSqlHelp();

        DataTable l_dt = l_Sh.SelectAdapter(Sql);

        if (l_dt.Rows.Count == 0)

            throw new Exception("查無客戶資料!");

        else

        {

            ArrayList list = new ArrayList();

            CEn en1 = new CEn();

            en1.id = "A1";

            en1.size = "100";

            en1.sn = "Ray";

            CEn en2 = new CEn();

            en2.id = "A2";

            en2.size = "500";

            en2.sn = "BigOne";

            list.Add(en1);

            list.Add(en2);

            return GetJsonData(list);

        }

    }

    private string GetJsonData(IList p_list)

    {

        JavaScriptSerializer JS = new JavaScriptSerializer();

        return JS.Serialize(p_list);

    }

若查無資料時，WebService會將Exception的相關資訊傳給ajax的error接收，

而在error中的xhr.responseText 設立中斷點，可以看到接收Json格式如下:

{"Message":"查無資料!"

,"StackTrace":"   於 WebService.GetJsonSend(List`1 p_list) 於 d:\\AjaxWeb\\App_Code\\WebService.cs: 行 30"

,"ExceptionType":"System.Exception"}

利用Json.parse();將其轉為物件，再利用Jquery.each輪巡，

就可以抓到Key為Message的Value，也就是我們在後端所拋出的Exception的訊息!