asp.net generic handler not sending images for the first time - asp.net

Question

I created a generic handler (.ashx) in ASP.Net to load images from database & send it to browser.
I am using a colorbox to display this in a separate page which only has an image control & calls this handler via ImageUrl property.
For the first time, Image is not being shown in the color box. For the subsequent requests, Image is getting shown.
I tried debugging to find that for the subsequent requests browser is not using a round trip but showing from cache.
How do I make it show the first time as well ?
public class DocumentViewer : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
string querystring = context.Request.QueryString.ToString();
try
{
if (querystring != null && querystring.Trim().Length == 0)
{
context.Response.ContentType = "text/plain";
context.Response.Write("Error");
context.Response.Write("No");
return;
}
string DocCode = querystring;
DocumentInfoBL bl = new DocumentInfoBL();
DataTable dt = bl.GetDocumentInfo(DocCode);
if (dt.Rows.Count == 0)
{
context.Response.ContentType = "text/plain";
context.Response.Write("Error");
context.Response.Write("No");
return;
}
context.Response.Clear();
context.Response.ClearContent();
context.Response.ClearHeaders();
context.Response.Cache.SetCacheability(HttpCacheability.Public);
context.Response.Cache.SetExpires(DateTime.MinValue);
// context.Response.ContentType = "application/octet-stream";
context.Response.ContentType = MimeMapping.GetMimeMapping(System.IO.Path.GetFileName(dt.Rows[0]["DocumentFileName"].ToString()));
context.Response.AddHeader("content-disposition", "inline; filename=" + System.IO.Path.GetFileName(dt.Rows[0]["DocumentFileName"].ToString()));
context.Response.BinaryWrite((Byte[])dt.Rows[0]["DocumentFile"]);
context.Response.Buffer = false;
context.Response.Flush();
}
catch (Exception ex)
{
context.Response.ContentType = "text/plain";
context.Response.Write("Error");
context.Response.Write("No");
return;
}
}
public bool IsReusable
{
get
{
return false;
}
}
}

Answer 1

Code that works.It is either charset or Buffer.
public void ProcessRequest(HttpContext context)
{
string querystring = context.Request.QueryString.ToString();
try
{
if (querystring != null && querystring.Trim().Length == 0)
{
context.Response.ContentType = "text/plain";
context.Response.Write("Error");
context.Response.Write("No");
return;
}
string DocCode = querystring;
DocumentInfoBL bl = new DocumentInfoBL();
DataTable dt = bl.GetDocumentInfo(DocCode);
if (dt.Rows.Count == 0)
{
context.Response.ContentType = "text/plain";
context.Response.Write("Error");
context.Response.Write("No");
return;
}
context.Response.Clear();
context.Response.ClearContent();
context.Response.ClearHeaders();
context.Response.Cache.SetCacheability(HttpCacheability.Public);
context.Response.Cache.SetExpires(DateTime.MinValue);
context.Response.ContentType = MimeMapping.GetMimeMapping(System.IO.Path.GetFileName(dt.Rows[0]["DocumentFileName"].ToString()));
context.Response.AddHeader("content-disposition", "inline; filename=" + System.IO.Path.GetFileName(dt.Rows[0]["DocumentFileName"].ToString()));
context.Response.Buffer = true;
context.Response.Charset = "";
context.Response.BinaryWrite((Byte[])dt.Rows[0]["DocumentFile"]);
context.Response.Flush();
}
catch (Exception ex)
{
//Manage here
context.Response.ContentType = "text/plain";
context.Response.Write("Error");
context.Response.Write("No");
return;
}
context.Response.End();
}