trouble using httphandler to retrieve image url - asp.net

Question

I am trying to write a httphandler to retrieve image url and later display it on a image control i am using this code but its not working
OleDbConnection mDB = new OleDbConnection(
ConfigurationManager.ConnectionStrings["AccessConnection"].ConnectionString);
mDB.Open();
OleDbCommand cmd = new OleDbCommand("select pProductId from Products where pProductId=" + context.Request.QueryString["ImageID"], mDB);
OleDbDataReader rdr = cmd.ExecuteReader();
rdr.Read();
context.Response.BinaryWrite((byte[])rdr[0]);
mDB.Close();
context.Response.End(); */
sorry that i caused a confusion earlier in the SELECT statement the pProductId does not contain the URL of the image instead pProductImage is the field that contain the URL. i am using the Id to identify which image to display accordingly.
this is my expected output:
<img src="ImgHandler.ashx?pProductId=2" alt="" />
i cant place image this is the link to my error msg:http://imgur.com/Cix67

Answer 1

This is a two steps answer.
In the page, you can do something like this:
using (OleDbConnection mDB = new OleDbConnection(ConfigurationManager.ConnectionStrings["AccessConnection"].ConnectionString))
{
mDB.Open();
using (OleDbCommand cmd = new OleDbCommand("select pProductId from Products where pProductId=" + context.Request.QueryString["ImageID"], mDB))
{
using (OleDbDataReader rdr = cmd.ExecuteReader())
{
rdr.Read();
context.Response.Write("<img src=\"ImgHandler.ashx?pProductId=");
context.Response.Write((int)rdr[0]); // I suppose pProductId is an int, adapt accordingly
context.Response.Write("\" />");
}
}
}
and in the HTTP handler implicitly triggered, something like this:
public class MyHandler : IHttpHandler
{
public bool IsReusable
{
get { return true; }
}
public void ProcessRequest(HttpContext context)
{
using (OleDbConnection mDB = new OleDbConnection(ConfigurationManager.ConnectionStrings["AccessConnection"].ConnectionString))
{
mDB.Open();
// select the file data (I put pData here as a placeholder, and assume it will be a byte[])
using (OleDbCommand cmd = new OleDbCommand("select pData from Products where pProductId=" + context.Request.QueryString["ImageID"], mDB))
{
using (OleDbDataReader rdr = cmd.ExecuteReader())
{
rdr.Read();
context.Response.ContentType = "image/png";// put the content type here
context.Response.BinaryWrite((byte[])rdr[0]);
}
}
}
}
}
Note the using pattern which ensures proper resources cleanup once used. Also, ideally you could cache the data on the client using proper cache HTTP headers (like if-modified-since) but this is another story ...