How can I get json data thru ajax

Question

I'm trying to create a chart page that updates every 5 seconds based on flotr2. But I'm having some problems with the return from the server, I get

[object, Object],[object, Object],[object, Object],[object, Object],[object, Object],[object, Object],[object, Object]

The javascript looks like:

    function updateFunc() {

        new Ajax.Request('http://localhost:53083/Home/Data', {
            method: 'get',
            onSuccess: function (transport) {
                var json = transport.responseText.evalJSON();
                alert(json);
            }
        });
    }

    updateFunc();

And the asp.net/c# looks like:

        //
        // GET: /Home/Data

        public string Data()
        {
            dt.Rows.RemoveAt(0);

            dt.Rows.Add(rand.Next(1, 50));

            return JsonConvert.SerializeObject(dt);
        }

dt is just a static datatable where i remove the first and add a new, creating a feel of continuous update.

What is wrong? As posted all i get is the [object, Object] from the alert.

score 2 · Accepted Answer · edited May 23 '17 at 11:51

You need to change the response's media type to say it is JSON so the client will interpret it correctly:
```
Response.ContentType = "application/json";
```
(See here for the reference to the correct type.)
It appears that JsonConvert doesn't know how to serialise the type of dt. Either change to a type that it can serialise, or tell it how to serialise that type: see the JSON.Net documentation.

How can I get json data thru ajax

1 Answers1