Postback causes image to disappear

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ASP.NET

WebForms

C#3.5

Hello Everyone,

I am having an issue maintaining a displayed image in Asp.net Webforms application after a postback. Basically, my application contains a CreateEmployee page where administrators can choose a profile image of an employee and fill out all the other necessary details.The image in the image control is displayed via a generic handler -for the preview of the image before uploading. There are other controls, such as a dropdownlist that causes a postback, which in turn causes the displayed image to dissapear. The relevant code is listed below:

The fileupload control (AsyncUpload -ajaxcontroltoolkit):

<ajaxToolkit:AsyncFileUpload ID="fUploadProfilePic"
                 runat="server"
                />

//The javascript to display the image

function getRandomNumber() {

    var randomNumber = Math.random(10000);
    return randomNumber;
}

function onFileUploadProfilePic(sender, args) {

    var handlerPage = '<%= Page.ResolveClientUrl("~/Handlers/ImageHandler.ashx")%>';
    var queryString = '?randomno=' + getRandomNumber();
    var src = handlerPage + queryString;
    var clientID = '<%= imgProfilePic.ClientID%>';
    document.getElementById(clientID).setAttribute("src", src);
}

// The event handler for fileupload uploaded complete event.
EDIT: This event handler is called twice. During the process, the data (byte[]) in the second run has all it's indexes converted to 0...[0]=0,[1]=0,[2]=0...etc. I want to know why this is happening as the 'HttpPostedFile' passed to the ReadFile method is still legit.

protected void fUploadProfilePic_UploadedComplete(object sender,
            AjaxControlToolkit.AsyncFileUploadEventArgs e)
        {

            if(fUploadProfilePic.PostedFile!=null)
            {
                HttpPostedFile file = fUploadProfilePic.PostedFile;

                byte[] data = Utilities.ImageUtil.ReadFile(file);

               
                Session[EmployeeBLL.STORED_IMAGE] = data;
                
            }

        }

//The ImageHandler.ashx code

public void ProcessRequest(HttpContext context)
       {
           context.Response.Clear();

           if(context.Session[EmployeeBLL.STORED_IMAGE]!=null)
           {
               var storedImage = context.Session[EmployeeBLL.STORED_IMAGE] as byte[];

               if(storedImage!=null)
               {
                   System.Drawing.Image image = GetImage(storedImage);

                   if(image!=null)
                   {
                       context.Response.ContentType = "image/jpeg";
                       image.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
                   }
               }
           }

       }

       private System.Drawing.Image GetImage(byte[] image)
       {
           var stream = new MemoryStream(image);
           return System.Drawing.Image.FromStream(stream);
       }

When debugging the code, i noticed that the eventhandler is executed twice. In the second run, the byte[] data's content is all 0's -i.e the following section:

byte[] data = Utilities.ImageUtil.ReadFile(file);


Session[EmployeeBLL.STORED_IMAGE] = data;

I am not sure what is causing this behavior. This might also be the reason why the image is not displaying. The ReadFile definition is as follows:

public static byte[] ReadFile(HttpPostedFile file)
        {
            byte[] data = new Byte[file.ContentLength];

            file.InputStream.Read(data, 0, file.ContentLength);

            return data;

        }

//Finally,
//The page_load code for maintaining the state of the fileupload control

protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
                initializeComponents();

            if (Session["fUpload"] == null && fUploadProfilePic.HasFile)
                Session["fUpload"] = fUploadProfilePic;
            else if (Session["fUpload"] != null && (!fUploadProfilePic.HasFile))
                fUploadProfilePic = (AsyncFileUpload)Session["fUpload"];
            else if (fUploadProfilePic.HasFile)
                Session["fUpload"] = fUploadProfilePic;
        }

Can someone please assist in pointing out the error?