Sql Image Upload And Retrieval?

Hi all,

I dont know if anyone here can help me...

I am using ASP.NEt with VB.Net and SQL Sever...

What I am trying to do is create a system whereby it allows users to upload images into sql server, and thereon later retireve this image.

I used a book called The Ultimate VB.Net and ASP.Net Code Book, and it basically gave me the code below to upload and retrieve images.  I seem to have managed to allow the uploading of images, with them being stored as <byte> in my database, thought I have no idea how to retrieve them...

Does anyone have any ideas???

Here is the code I followed.. :


"

Storing Uploaded Files in Your Database
 

First, a few tips on storing files inside your SQL Server database.

For convenience, you’ll really need to store at least three bits of information about your file to get it out in the same shape as you put it in. I’d suggest “data� (a field that will hold your actual file as a byte array, data type “image�), “type� (a field to hold details of the type of file it is, data type “varchar�), and “length� (a field to hold the length in bytes of your file, data type “int�).

I’d also recommend “downloadName�, a field to hold the name that the file had when it was uploaded, data type “varchar�. This helps suggest a name should the file be downloaded again via the Web.

The problem you have is translating the information from the File Field control into an acceptable format for your database. For a start, you need to get your file into a byte array to store it in an image field. You also need to extract the file type, length, and the download name. Once you have this, set your fields to these values using regular ADO.NET code.

So, how do you get this information? It’s simple: just use the following ready-to-run code snippets, passing in your File Field control as an argument. Each function will return just the information you want to feed straight into your database, from a byte array for the image field to a string for the file type.

Public Function GetByteArrayFromFileField( _
    ByVal FileField As System.Web.UI.HtmlControls.HtmlInputFile) _
    As Byte()
    ' Returns a byte array from the passed
    ' file field controls file
    Dim intFileLength As Integer, bytData() As Byte
    Dim objStream As System.IO.Stream
    If FileFieldSelected(FileField) Then
        intFileLength = FileField.PostedFile.ContentLength
        ReDim bytData(intFileLength)
        objStream = FileField.PostedFile.InputStream
        objStream.Read(bytData, 0, intFileLength)
        Return bytData
    End If
End Function

Public Function FileFieldType(ByVal FileField As _
  System.Web.UI.HtmlControls.HtmlInputFile) As String
    ' Returns the type of the posted file
    If Not FileField.PostedFile Is Nothing Then _
      Return FileField.PostedFile.ContentType
End Function

Public Function FileFieldLength(ByVal FileField As _
  System.Web.UI.HtmlControls.HtmlInputFile) As Integer
    ' Returns the length of the posted file
    If Not FileField.PostedFile Is Nothing Then _
      Return FileField.PostedFile.ContentLength
End Function
Public Function FileFieldFilename(ByVal FileField As _
  System.Web.UI.HtmlControls.HtmlInputFile) As String
    ' Returns the core filename of the posted file
    If Not FileField.PostedFile Is Nothing Then _
      Return Replace(FileField.PostedFile.FileName, _
      StrReverse(Mid(StrReverse(FileField.PostedFile.FileName), _
      InStr(1, StrReverse(FileField.PostedFile.FileName), ""))), "")
End Function
Sorted! One question remains, however. Once you’ve got a file inside a database, how do you serve it back up to a user? First, get the data back out of SQL Server using regular ADO.NET code. After that? Well, here’s a handy function that’ll do all the hard work for you. Simply pass the data from your table fields and hey presto:

Public Sub DeliverFile(ByVal Page As System.Web.UI.Page, _
  ByVal Data() As Byte, ByVal Type As String, _
  ByVal Length As Integer, _
  Optional ByVal DownloadFileName As String = "")
    ' Delivers a file, such as an image or PDF file,
    ' back through the Response object
    ' Sample usage from within an ASP.NET page:
    ' - DeliverFile(Me, bytFile(), strType, intLength, "MyImage.bmp")
    With Page.Response
        .Clear()
        .ContentType = Type
        If DownloadFileName <> "" Then
            Page.Response.AddHeader("content-disposition", _
              "filename=" & DownloadFileName)
        End If
        .OutputStream.Write(Data, 0, Length)
        .End()
    End With
End Sub
Simply pass your byte array, file type, and length, and it’ll send it straight down to your surfer. If it’s an image, it’ll be displayed in the browser window. If it’s a regular file, you’ll be prompted for download.

If it’s made available for download, this function also allows you to specify a suggested download file name, a technique that many ASP.NET developers spend weeks trying to figure out. Easy!


Working with Uploaded Images
 

Whether you’re building the simplest of photo album Web sites or a fully fledged content management system, the ability to work with uploaded images is a vital one, and with ASP.NET, it’s a real doddle.

The following code snippet shows you how, by example. It takes a data stream from the File Field control and converts it into an image object, adding simple error handling should the uploaded file not actually be an image. The code then uses this image object to extract a few core details about the file, from its dimensions to file type:

' Get data into image format
Dim objStream As System.IO.Stream = _
  MyFileField.PostedFile.InputStream
Dim objImage As System.Drawing.Image
Try
    ' Get the image stream
    objImage = System.Drawing.Image.FromStream(objStream)
Catch
    ' This is not an image, exit the method (presuming code is in one!)
    Exit Sub
End Try
' Filename
Dim strOriginalFilename As String = MyFileField.PostedFile.FileName
' Type of image
Dim strImageType
If objImage.RawFormat.Equals(objImage.RawFormat.Gif) Then
    strImageType = "This is a GIF image"
ElseIf objImage.RawFormat.Equals(objImage.RawFormat.Bmp) Then
    strImageType = "This is a Bitmap image"
ElseIf objImage.RawFormat.Equals(objImage.RawFormat.Jpeg) Then
    strImageType = "This is a JPEG image"
ElseIf objImage.RawFormat.Equals(objImage.RawFormat.Icon) Then
    strImageType = "This is an icon file"
ElseIf objImage.RawFormat.Equals(objImage.RawFormat.Tiff) Then
    strImageType = "This is a TIFF file"
Else
    strImageType = "Other"
  End If
  ' Dimensions
  Dim strDimensions As String
  strDimensions = "Width in pixels: " & objImage.Width & _
    ", Height in pixels: " & objImage.Height
  ' Send raw output to browser
  Response.Clear()
  Response.Write(strOriginalFilename & "<p>" & strImageType & _
    "<p>" & strDimensions)
  Response.End()


"


For some reason the retrieval code isnt working for me..

Can anyone provide any help? even if it means using another method?