Sending parameters to jquery callback

Question

I am making a jquery call from a javascript method. I want a parameter to be sent to my call back method. I am using a handler(ashx) to make jquery call, the handler is getting invoked but the callback is not getting fired. Below is the code

function MyButtonClick(){
var myDiv = "divname";
$.post("MyHandler.ashx", { tgt: 1 }, myDiv, CustomCallBack);
}

function CustomCallBack(data, result) {
        debugger;
        //SomeCode
    }
}

Handler code(ashx file)

public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";

            int tgt = Convert.ToInt32(context.Request["tgt"]);
            if (tgt == 1)
            {
                          context.Response.Write("Some text");
            }
        }

Answer 1

Have you had a look at this page : http://docs.jquery.com/How_jQuery_Works#Callback_with_arguments

Should you be using a $.get(... call?

    $.get("MyHandler.ashx", { tgt: 1 }, myDiv, function() {
        CustomCallBack(data, result);
    });

Answer 2

In your ashx, you need to get the data from reading the post data...

    StringBuilder HttpInputStream;

    public void ProcessRequest(HttpContext context)
    {

        HttpInputStream = new StringBuilder();
        GetInputStream(context);

       // the data will be in the HttpInputStream now
       // What you might want to do it to use convert it to a .Net class ie,
       // This is using Newtonsoft JSON
       // JsonConvert.DeserializeObject<JsonMessageGet>(HttpInputStream.ToString());

    }

    private void GetInputStream(HttpContext context)
    {
        using (Stream st = context.Request.InputStream)
        {
            byte[] buf = new byte[context.Request.InputStream.Length];
            int iRead = st.Read(buf, 0, buf.Length);
            HttpInputStream.Append(Encoding.UTF8.GetString(buf));
        }
    }

In your response back the caller - your ashx needs to respond in JSON so the caller JavaScript can consume it.

I suggest using Newstonsoft JSON eg...

 public void ProcessRequest(HttpContext context)
 {
     // read from stream and process (above code)

     // output
     context.Response.ContentType = "application/json";
     context.Response.ContentEncoding = Encoding.UTF8;
     context.Response.Write(JsonConvert.SerializeObject(objToSerialize, new IsoDateTimeConverter()));
 }

OR to make it really really easy, change to - basically needs to respond back in JSON for the JavaScript handler to process it

    public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "application/json";
        context.Response.Write("{data:\"Reply message\"}");
    }