Question

This is my JSON string generated by C# JSON parser:

{
    "NewDataSet": {
        "Table": [
            {
                "ResultId": "1",
                "AttachmentId": "1",
                "AttachmentName": "Report1",
                "RowsCount": "34",
                "NotifyUserName": "william",
                "InsBy": "developer",
                "InsAt": "2012-12-07T17:28:01.46+08:00",
                "IsNotify": "false"
            },
            {
                "ResultId": "2",
                "AttachmentId": "2",
                "AttachmentName": "Report2",
                "RowsCount": "37",
                "NotifyUserName": "william",
                "InsBy": "developer",
                "InsAt": "2012-12-07T17:28:15.57+08:00",
                "IsNotify": "false"
            },
            {
                "ResultId": "3",
                "AttachmentId": "3",
                "AttachmentName": "Report3",
                "RowsCount": "69",
                "NotifyUserName": "william",
                "InsBy": "developer",
                "InsAt": "2012-12-07T17:28:25.58+08:00",
                "IsNotify": "false"
            }
        ]
    }
}

Then I would like to parse the string to front end JavaScript to iterate the value.
I did this way.

  var jsonText;
        $.ajax({
            type: "POST",
            url: "Default.aspx/MethodWithNoParameterJSON",
            data: {},
            contentType: "application/json;charset=utf-8",
            dataType: "json",
            async: true,
            cache: false,
            success: function (msg) {
                //rulesName = dbtitle+msg.d;
                //rulesCount = +msg.d;
                jsonText = msg.d;
               alert(jsonText.NewDataSet.Table[0].ResultId), 
            },
            error: function (x, e) {
                alert("The call to the server side failed. " + x.responseText);
            }
        });

How can I get the child element data like jsonText.NewDataSet.Table[0].ResultId? Whenever I call alert(jsonText.NewDataSet.Table[0].ResultId), it will always prompt null or undefined object.

Answer 1

Why are you using msg.d to set your jsonText variable? Where does the .d property come from? The msg parameter should already be the object created from your JSON response. Try this instead:

msg.NewDataSet.Table[0].ResultId

(And note that your jsonText variable is badly named: what you have at that point is not JSON or “text”, it is an object – or, in your case, undefined because msg.d is undefined. But you are trying to use it as an object, not as JSON.)