dynamic image (from db) using Generic Handler

Question

I'm trying to using a Generic Handler to retrieve and display images that are stored in a database.

But its just not working. Ive tried verious of the code below, but I cant seem to get it to work.

Can anyonne spot what I am doing wrong, or have some suggestions?

<%@ WebHandler Language="C#" Class="IconsDb" %>

using System;
using System.Web;
using System.Linq;
using System.Data.Entity;

public class IconsDb : IHttpHandler {

    public void ProcessRequest (HttpContext context) {
        context.Response.ContentType = "text/plain";
        context.Response.Write("Hello World");
        Int32 iconId;

        if (context.Request.QueryString["id"] != null)
            iconId = Convert.ToInt32(context.Request.QueryString["id"]);
        else
            throw new ArgumentException("No parameter specified");

        context.Response.ContentType = "image/gif";
        //System.IO.Stream strm = ShowEmpImage(iconId);

        var db = new UdINaturen.UdINaturenContext();

        var GetIcon = (from i in db.subcategoryicons
                       where i.id == iconId
                       select i.picture).FirstOrDefault();
        object img = GetIcon;

        System.IO.MemoryStream memStream= new System.IO.MemoryStream((byte[])Convert.FromBase64String(GetIcon));
        System.Drawing.Bitmap bitImage=new System.Drawing.Bitmap((System.Drawing.Bitmap)System.Drawing.Image.FromStream(memStream));


        byte[] buffer = memStream.ToArray();
        context.Response.ContentType = "image/gif";
        //context.Response.OutputStream.Write(buffer, 0, buffer.Length);
        //context.Response.WriteFile();
        context.Response.BinaryWrite(buffer);
        //context.Response.Flush();


    }





    public bool IsReusable {
        get {
            return true;
        }
    }

}

why are you setting your content type to plain text on line 2? — Ta01
– Ta01, Commented Feb 9, 2010 at 18:01
why do you convert the byte array to a MemoryStream to a Bitmap to a byte array? — dtb
– dtb, Commented Feb 9, 2010 at 18:03

FallenAvatar · Accepted Answer · 2010-02-10 17:42:13Z

3

wow, ok. Not sure how much of that is old code, what should be commented out or w/e but try something like this:

public void ProcessRequest (HttpContext context) {
    int iconId;

    if (string.IsNullOrEmpty(context.Request.QueryString["id"]) || !int.TryParse(context.Request.QueryString["id"], out iconId) )
        throw new ArgumentException("No parameter specified");

    context.Response.ContentType = "image/gif";

    var db = new UdINaturen.UdINaturenContext();

    var GetIcon = (from i in db.subcategoryicons
                   where i.id == iconId
                   select i.picture).FirstOrDefault();
    byte[] buffer = (byte[])Convert.FromBase64String(GetIcon);

    context.Response.ContentType = "image/gif";
    context.Response.BinaryWrite(buffer);
    context.Response.Flush();
}

edited Feb 10, 2010 at 17:42

answered Feb 9, 2010 at 18:11

FallenAvatar

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2 Comments

dtb Over a year ago

You accidentally erased Convert.FromBase64String

Joel Coehoorn Over a year ago

I might also have a generic "invalid parameter" image for the handler to return rather than throwing an exception, but that's a personal preference.

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