problem in getting Value from Json Key Value Pair

Question

Hi everyone, I am following this link to build a Client side repeater.

According to the above link to retrive the value from a Json key-value pair we can use result[i].property,for example

for (var post in msg)
{     
    var x= msg[post].Date;
    alert(x);
}

Here x returns the date from Json string. When I am trying to use the same with my data, it always returns as undefined. I tried to pop up an alert(msg.d) that shows a nice Json string with all my data. But when I try msg[post].Date(property name) it's always returning undefined.

Please help..

Thanks in advance.

Update:

From the backend I am returning a generic list and then converting it into Json using the following code.

public static string ConvertToJSON(this object obj) {

    DataContractJsonSerializer serializer = new DataContractJsonSerializer(obj.GetType());    

    MemoryStream ms = new MemoryStream();
    serializer.WriteObject(ms, obj);
    string jsonobj = Encoding.Default.GetString(ms.ToArray());
    ms.Dispose();
    return jsonobj;
}

then I am appending the returned Json to a stringbuilder and returning it to the Jquery ajax method.The returned Json looks like a string , not an object and hence I am unable to get any value from Json key value pair..

Answer 1

What about the message, if you add this to your ajax does that help?

dataFilter: function(data)
            {
                var msg;
                if (typeof (JSON) !== 'undefined' &&
                typeof (JSON.parse) === 'function')
                    msg = JSON.parse(data);
                else
                    msg = eval('(' + data + ')');
                if (msg.hasOwnProperty('d'))
                    return msg.d;
                else
                    return msg;
            },

Note that you then process this as msg, not msg.d like so:

success: function(msg)
            {
                SaveSuccess(msg);
            },

Answer 2

Looks to me like you got an array of objects to begin with, using your sample the following works:

messages = [{"AnsNo":0,"Answer":"","Category":"Help Centre.Mortgages.Existing customers","ClickURL":null,"ID":7,"Question":"How do I re-mortgage to you?","RecNo":0,"ValidFrom":"\/Date(-62135596800000+0000)\/","ValidUntill":"\/Date(-62135596800000+0000)\/"}]

for(i in messages)
{
    message = messages[i];
    //Says "Help Centre.Mortgages.Existing customers"
    alert(message.Category)
    //To get all key/value pairs
    for(key in message)
    {
        //Alerts all key value pairs one by one
        alert("Key:" + key + ", Value:" + message[key]);
    }
}

Answer 3

Update:

It sounds like you're doubly serializing the data on the server-side, returning a JSON string that gets serialized as JSON itself. When that reaches the client-side and jQuery deserializes the first layer of JSON automatically, you're still left with the JSON string you manually built.

You should return the List<T> as the return value of your service method and let the framework handle JSON serialization.

Original Answer:

Assuming the object is still contained in ASP.NET AJAX's ".d" wrapper, as you implied:

for (var post in msg.d) {     
  var x = msg.d[post].Date;

  alert(x);
}

Or, a traditional loop, which might be more straightforward:

for (var i = 0; i < msg.d.length; i++) {
  var x = msg.d[i].Date;

  alert(x);
}