Problem bringing back images from database

[webwiz082]

Hi all:

I'm currently working on a project and basically have come to a standstill, and was wondering if you could help me out. Most of this requires knowledge of ASP.net and VB.net. I'm attempting to dynamically retrieve multiple images from a SQL database and display it onto an ASP (.aspx) page depending upon what the user selects. Currently I have a .ASHX page bringing back the images, but right now, it's just displaying the very first image. I'm trying to get it to retrieve ALL the images that the SELECT statement brings back, and display all of them. I figured if I can get the very first one to display, I should be able to get the rest of them to display as well.

Here's the code. Please bear in mind this is a condensed verison:

.ASHX page

<%@ WebHandler Language="VB" Class="FileHandler" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.SQLClient" %>
<%@ import Namespace="System.IO" %>
<%@ import Namespace="System.Web.UI.WebControls" %>
<%@ import Namespace="System.Web.UI.HtmlControls" %>
<%@ import Namespace="System.Web.Mail" %>

Imports System
Imports System.Web
Imports System.Data
Imports System.Data.SqlClient

Public Class FileHandler
Implements IHttpHandler

Const conString As String = "server/db"

Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest


Dim con As SqlConnection = New SqlConnection(conString)

Dim cmd As SqlCommand = New SqlCommand("SELECT FileImage, FileType, filename FROM Attachments WHERE ArticleId=@ArticleId", con)
cmd.Parameters.AddWithValue("@ArticleId", context.Request("ArticleId"))


Using con
con.Open()

Dim ds As New DataSet
Dim da As New SqlDataAdapter(cmd, con)
Dim arrContent As Byte()
Dim dr As DataRow

da.Fill(ds)
dr = ds.Tables(0).Rows(Convert.ToInt32(Request.QueryString("ImageIndex"))).Item("FileImage")
arrContent = CType(dr.Item("FileImage"), Byte())
Dim conType As String = dr.Item("FileType").ToString()
Response.ContentType = conType
Response.OutputStream.Write(arrContent, 0, dr.Item("filename"))
Response.End()

con.Close()
End Using

End Sub

Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
Get
Return False
End Get
End Property

End Class

And then I have the .aspx, which is supposed to display the images

<%@ Page Language="VB" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.SQLClient" %>
<%@ import Namespace="System.IO" %>
<%@ import Namespace="System.Web.UI.WebControls" %>
<%@ import Namespace="System.Web.UI.HtmlControls" %>
<%@ import Namespace="System.Web.Mail" %>

<script language=vbscript runat="server">
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

If Not Page.IsPostBack Then

Dim connStr As String = "server/db"
Dim DBReader As SqlDataReader
Dim Article As String = Request.QueryString("ArticleID")
Dim DBConnection As SqlConnection = New SqlConnection(connStr)
Dim MySQL As String = "Select * from Vw_Article Where ArticleID = " & Article
Dim DBCommand As New SqlCommand(MySQL, DBConnection)

DBConnection.Open()

DBReader = DBCommand.ExecuteReader()
DetailList.DataSource = DBReader
DetailList.DataBind()
DBReader.Close()
DBConnection.Close()


End If
End Sub

<asp:Image ID="image1" runat="server" ImageUrl='<%#Eval("Articleid", "documenthandler-test.ashx?Articleid={0}&ImageIndex=0")%>'/>
<asp:Image ID="image2" runat="server" ImageUrl='<%#Eval("Articleid", "documenthandler-test.ashx?Articleid={0}&ImageIndex=1")%>'/>
<asp:Image ID="image3" runat="server" ImageUrl='<%#Eval("Articleid", "documenthandler-test.ashx?Articleid={0}&ImageIndex=2")%>'/>
<asp:Image ID="image4" runat="server" ImageUrl='<%#Eval("Articleid", "documenthandler-test.ashx?Articleid={0}&ImageIndex=3")%>'/>

The ImageIndex is what supposed to bring back each individual image, for this particular ArticleID, there's four images.

Could someone please take a look at this code and tell me what I'm doing wrong. I need this for work.

Thanks,
-Wes

[mendhak]

Compile your project, run it. Then, try accessing the page directly, by browsing directly to:

http://localhost/something/documenth...1&ImageIndex=3

Make sure there's a breakpoint at

da.Fill(ds)

Also ensure that you change

SELECT FileImage, FileType, filename FROM Attachments WHERE ArticleId=@ArticleId

to

SELECT ArticleId, FileImage, FileType, filename FROM Attachments WHERE ArticleId=@ArticleId

Also, have it return AttachmentsId? Surely there's a primary key of some sort in that table?

Once that line executes (F10), do a quickwatch on ds, and try to see what value is returned in AttachmentsId/ArticleId along with the other fields. You must be able to determine whether the same row is being repeated 4 times. There should be at least 4 different filename fields, right?

Now, try browsing to the same page with ImageIndex = 0, then 1, then 2, then 3. This stepping through as well as direct browsing should help you narrow down the problem, as to why the same image appears 4 times. Might even be a caching issue.