VB.NET get bytes from SQL Table - asp.net

Question

It's been a while since I've been here. I've been working on an ASP project where the attachment is stored to DB. I'm trying to get the bytes stored in the table to a file.
I was able to make the file, however, I couldn't get the bytes from the table.
This is the code that enters the file to the table:
'Saves the upload file data to database for the using Request_ID after the request has been created
strFileName = FileUploadReqDtl.FileName
strFileExt = strFileName.Substring(strFileName.IndexOf(".") + 1)
intFileSize = FileUploadReqDtl.PostedFile.ContentLength()
Dim theDataSize As Byte() = New Byte(FileUploadReqDtl.PostedFile.ContentLength - 1) {}
Dim uploadedFile As HttpPostedFile = FileUploadReqDtl.PostedFile
Dim theData = uploadedFile.InputStream.Read(theDataSize, 0, CInt(FileUploadReqDtl.PostedFile.ContentLength))
I was able to create a link on a page that goes to another ASP page and tries to make the file downloadable. I know that the SQL is working properly to get the records from the table, however, I'm not able to get the bytes properly:
If (dr.HasRows = True) Then
While dr.Read()
' Casting the value returned by the datareader to the byte[] data type.
result = CType(dr.GetValue(0), Byte())
strFileName = dr.GetString(1)
Debug.Write("strFileName: " & strFileName & vbCrLf)
End While
End If
dr.Close()
cnToDb.Close()
ShowFile(strFileName, result, MimeType)
Catch ex As Exception
MsgBox("Uh oh, I couldn't get the attachment!")
Debug.Write("Uh oh, I couldn't get the attachment!")
Debug.Write(ex.Message & " - " & ex.StackTrace & vbCrLf & vbCrLf)
result = Nothing
End Try
This is the ShowFile function which finally "creates the file" with the bytes from the database:
Dim fileData() As Byte
fileData = byteFileData
Response.Clear()
Response.AddHeader("Content-Disposition", "attachment; filename=" + strFileName)
Response.ContentType = MimeType
Response.BinaryWrite(fileData)
Response.End()
Response.Flush()
The exception I'm hitting that I'm having issues with is:
SQL: SELECT Data, FileName FROM tblFileUploadData WHERE Report_ID =
116
strFileName: TheAwesomeAttachment.txt A first chance exception of type
'System.Threading.ThreadAbortException' occurred in mscorlib.dll Uh
oh, I couldn't get the attachment!Thread was being aborted. - at
System.Threading.Thread.AbortInternal() at
System.Threading.Thread.Abort(Object stateInfo) at
System.Web.HttpResponse.End() at
WebApplication3.WebForm2.ShowFile(String strFileName, Byte[]
byteFileData, String MimeType) in C:\Users\Mike\documents\visual
studio
2010\Projects\WebApplication3\WebApplication3\Attachment.aspx.vb:line
81 at WebApplication3.WebForm2.getAttachment(Int32 RequestID,
String MimeType) in C:\Users\Mike\documents\visual studio
2010\Projects\WebApplication3\WebApplication3\Attachment.aspx.vb:line
56
A first chance exception of type
'System.Threading.ThreadAbortException' occurred in
WebApplication3.DLL An exception of type
'System.Threading.ThreadAbortException' occurred in
WebApplication3.DLL but was not handled in user code The thread '<No
Name>' (0x728) has exited with code 0 (0x0). The program '[13512]
WebDev.WebServer40.EXE: Managed (v4.0.30319)' has exited with code 0
(0x0). The program '[13512] WebDev.WebServer40.EXE: Program Trace' has
exited with code 0 (0x0).

Answer 1

Take a look at:
http://support.microsoft.com/kb/312629
"For Response.End, call the HttpContext.Current.ApplicationInstance.CompleteRequest method instead of Response.End to bypass the code execution to the Application_EndRequest event"
I like to create an .ashx file for this type of situation. You can link to it and it will download the file without showing a page.
Public Class DownloadFile
Implements System.Web.IHttpHandler
Public Sub ProcessRequest(context As HttpContext) Implements IHttpHandler.ProcessRequest
Try
Dim id As String = context.Request.QueryString("id")
Dim filename As String = ""
Dim output As Byte()
filename = ServiceHelper.GetFilenameByID(id)
output = ServiceHelper.GetFileBytesByID(id)
Dim ext As String = System.IO.Path.GetExtension(filename)
Dim contenttype As String
'clear the current output content from the buffer
context.Response.Clear()
'add the header that specifies the default filename for the
'Download/SaveAs dialog
context.Response.AddHeader("Content-Disposition", "attachment; filename=" & filename)
'add the header that specifies the file size, so that the browser
'can show the download progress
context.Response.AddHeader("Content-Length", output.Length.ToString())
'specify that the response is a stream that cannot be read by the
'client and must be downloaded
'Response.ContentType = "application/octet-stream"
context.Response.Buffer = True
Select Case ext
Case ".doc"
contenttype = "msword"
Case ".pdf"
contenttype = "pdf"
Case ".xls"
contenttype = "x-excel"
Case ".ppt"
contenttype = "ms-powerpoint"
Case Else
contenttype = "octet-stream"
End Select
context.Response.ContentType = "application/" & contenttype
context.Response.BinaryWrite(output)
'http://support.microsoft.com/kb/312629
'context.Response.End()
context.ApplicationInstance.CompleteRequest()
Catch
End Try
End Sub
Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
Get
Return False
End Get
End Property
End Class