dhotchin — Wed, 01 Jun 2005 13:05:50 +0000

erm.... well i best start of by saying thank you for that. But its way over may head.

The system i trying to get working to a Intractive Intranet. staff can upload documents and so others can search for them. But.... what i dont want them to do is upload the same file and replace them.

Abhishek Reddy — Wed, 01 Jun 2005 12:34:01 +0000

Well, I'm sticking to a semi-conceptual description of what to do as I'm not confident guaranteeing my rusty VB/ASP will work.

What I'm suggesting is at the point where you know the name of the file trying to be uploaded and before it is copied to the final location, you simply check to see if a file of the same name already exists. This point is, if I'm right, within the loop that iterates over the files being sent that are to be copied.

This is done by using an if conditional and the FileExists method of a FileSystemObject. Server.MapPath is used to provide the proper physical path of the file to FileExists (adjust as necessary). Note that you might need to create a new FileSystemObject to do this, which, for illustrative purposes, I've called fs.

So if a pre-existing file is not found, then you can proceed with the copying as is presently the case. However if a conficting file does exist, you can handle the error in any number of ways. You could right then redirect the user to an error page (but this would halt uploads of subsequent files in fileItems). Or you could store the names of the conflicting items in another location/variable/file/database (whatever you please), and use that to report errors in the final page. Selecting the best strategy for this depends really on how the rest of your program operates, how errors are generally handled if there's already an error handling mechanism, and so on.

Hope that makes sense. If it's no help, tell me, and I'll see if I can write up some code.

dhotchin — Tue, 31 May 2005 22:03:50 +0000

Abhishek Reddy wrote: Probably in here:
For Each fileItem In UploadedFiles.Items'
you'll want to test if fs.FileExists(Server.MapPath(fileItem.FileName))=true. QUOTE]

Are you saying if i insert this line of code it will check to see if the file is already on the server? If so, what is the best way to send the user to a error page which states their problem?

There is a live demo of what i'm trying to do if you would like to look at it? You will need a username and password. just let me know if need.

bja888 — Tue, 31 May 2005 18:06:11 +0000

I hate VB

Abhishek Reddy — Tue, 31 May 2005 08:18:27 +0000

Probably in here:
For Each fileItem In UploadedFiles.Items'
you'll want to test if fs.FileExists(Server.MapPath(fileItem.FileName))=true. If it does exist, redirect to an error page. If it doesn't exist, proceed with the copy & save.

Or, rather than redirecting immediately, store a list a of conflicts somewhere, and use that in a report in the second page.

Any good?

dhotchin — Mon, 30 May 2005 19:29:49 +0000

I'm still having no luck. The script used above, acts if i already know the file, which i dont. I may be wrong.

I have two pages. the upload page with a text field and browse to computer form. Which has a file attached (code is below). Then when the file is uploaded browser open a new page which input the file name in to a text box and other details the user imputs then adds the data to a access database.

But i need something when the file is trying to be uploaded it then comes up with an error.

Upload script

<%
Class FreeASPUpload
	Public UploadedFiles
	Public FormElements

	Private VarArrayBinRequest
	Private StreamRequest
	Private uploadedYet

	Private Sub Class_Initialize()
		Set UploadedFiles = Server.CreateObject("Scripting.Dictionary")
		Set FormElements = Server.CreateObject("Scripting.Dictionary")
		Set StreamRequest = Server.CreateObject("ADODB.Stream")
		StreamRequest.Type = 1 'adTypeBinary
		StreamRequest.Open
		uploadedYet = false
	End Sub
	
	Private Sub Class_Terminate()
		If IsObject(UploadedFiles) Then
			UploadedFiles.RemoveAll()
			Set UploadedFiles = Nothing
		End If
		If IsObject(FormElements) Then
			FormElements.RemoveAll()
			Set FormElements = Nothing
		End If
		StreamRequest.Close
		Set StreamRequest = Nothing
	End Sub

	Public Property Get Form(sIndex)
		Form = ""
		If FormElements.Exists(LCase(sIndex)) Then Form = FormElements.Item(LCase(sIndex))
	End Property

	Public Property Get Files()
		Files = UploadedFiles.Items
	End Property

	'Calls Upload to extract the data from the binary request and then saves the uploaded files
	Public Sub Save(path)
		Dim streamFile, fileItem

		if Right(path, 1) <> "\" then path = path & "\"

		if not uploadedYet then Upload

		For Each fileItem In UploadedFiles.Items
			Set streamFile = Server.CreateObject("ADODB.Stream")
			streamFile.Type = 1
			streamFile.Open
			StreamRequest.Position=fileItem.Start
			StreamRequest.CopyTo streamFile, fileItem.Length
			streamFile.SaveToFile path & fileItem.FileName, 2
			streamFile.close
			Set streamFile = Nothing
			fileItem.Path = path & fileItem.FileName
		 Next
	End Sub

	Public Function SaveBinRequest(path) ' For debugging purposes
		StreamRequest.SaveToFile path & "\debugStream.bin", 2
	End Function

	Public Sub DumpData() 'only works if files are plain text
		Dim i, aKeys, f
		response.write "Form Items:<br>"
		aKeys = FormElements.Keys
		For i = 0 To FormElements.Count -1 ' Iterate the array
			response.write aKeys(i) & " = " & FormElements.Item(aKeys(i)) & "<BR>"
		Next
		response.write "Uploaded Files:<br>"
		For Each f In UploadedFiles.Items
			response.write "Name: " & f.FileName & "<br>"
			response.write "Type: " & f.ContentType & "<br>"
			response.write "Start: " & f.Start & "<br>"
			response.write "Size: " & f.Length & "<br>"
		 Next
   	End Sub

	Private Sub Upload()
		Dim nCurPos, nDataBoundPos, nLastSepPos
		Dim nPosFile, nPosBound
		Dim sFieldName, osPathSep, auxStr

		'RFC1867 Tokens
		Dim vDataSep
		Dim tNewLine, tDoubleQuotes, tTerm, tFilename, tName, tContentDisp, tContentType
		tNewLine = Byte2String(Chr(13))
		tDoubleQuotes = Byte2String(Chr(34))
		tTerm = Byte2String("--")
		tFilename = Byte2String("filename=""")
		tName = Byte2String("name=""")
		tContentDisp = Byte2String("Content-Disposition")
		tContentType = Byte2String("Content-Type:")

		uploadedYet = true

		on error resume next
		VarArrayBinRequest = Request.BinaryRead(Request.TotalBytes)
		if Err.Number <> 0 then 
			response.write "<br><br><B>System reported this error:</B><p>"
			response.write Err.Description & "<p>"
			response.write "The most likely cause for this error is the incorrect setup of AspMaxRequestEntityAllowed in IIS MetaBase. <p>"
			Exit Sub
		end if
		on error goto 0 'reset error handling

		nCurPos = FindToken(tNewLine,1) 'Note: nCurPos is 1-based (and so is InstrB, MidB, etc)

		If nCurPos <= 1  Then Exit Sub
		 
		'vDataSep is a separator like -----------------------------21763138716045
		vDataSep = MidB(VarArrayBinRequest, 1, nCurPos-1)

		'Start of current separator
		nDataBoundPos = 1

		'Beginning of last line
		nLastSepPos = FindToken(vDataSep & tTerm, 1)

		Do Until nDataBoundPos = nLastSepPos
			
			nCurPos = SkipToken(tContentDisp, nDataBoundPos)
			nCurPos = SkipToken(tName, nCurPos)
			sFieldName = ExtractField(tDoubleQuotes, nCurPos)

			nPosFile = FindToken(tFilename, nCurPos)
			nPosBound = FindToken(vDataSep, nCurPos)
			
			If nPosFile <> 0 And  nPosFile < nPosBound Then
				Dim oUploadFile
				Set oUploadFile = New UploadedFile
				
				nCurPos = SkipToken(tFilename, nCurPos)
				auxStr = ExtractField(tDoubleQuotes, nCurPos)
                ' We are interested only in the name of the file, not the whole path
                ' Path separator is \ in windows, / in UNIX
                ' While IE seems to put the whole pathname in the stream, Mozilla seem to 
                ' only put the actual file name, so UNIX paths may be rare. But not impossible.
                osPathSep = "\"
                if InStr(auxStr, osPathSep) = 0 then osPathSep = "/"
				oUploadFile.FileName = Right(auxStr, Len(auxStr)-InStrRev(auxStr, osPathSep))

				if (Len(oUploadFile.FileName) > 0) then 'File field not left empty
					nCurPos = SkipToken(tContentType, nCurPos)
					
                    auxStr = ExtractField(tNewLine, nCurPos)
                    ' NN on UNIX puts things like this in the streaa:
                    '    ?? python py type=?? python application/x-python
					oUploadFile.ContentType = Right(auxStr, Len(auxStr)-InStrRev(auxStr, " "))
					nCurPos = FindToken(tNewLine, nCurPos) + 4 'skip empty line
					
					oUploadFile.Start = nCurPos-1
					oUploadFile.Length = FindToken(vDataSep, nCurPos) - 2 - nCurPos
					
					If oUploadFile.Length > 0 Then UploadedFiles.Add LCase(sFieldName), oUploadFile
				End If
			Else
				Dim nEndOfData
				nCurPos = FindToken(tNewLine, nCurPos) + 4 'skip empty line
				nEndOfData = FindToken(vDataSep, nCurPos) - 2
				If Not FormElements.Exists(LCase(sFieldName)) Then FormElements.Add LCase(sFieldName), String2Byte(MidB(VarArrayBinRequest, nCurPos, nEndOfData-nCurPos))
			End If

			'Advance to next separator
			nDataBoundPos = FindToken(vDataSep, nCurPos)
		Loop
		StreamRequest.Write(VarArrayBinRequest)
	End Sub

	Private Function SkipToken(sToken, nStart)
		SkipToken = InstrB(nStart, VarArrayBinRequest, sToken)
		If SkipToken = 0 then
			Response.write "Error in parsing uploaded binary request."
			Response.End
		end if
		SkipToken = SkipToken + LenB(sToken)
	End Function

	Private Function FindToken(sToken, nStart)
		FindToken = InstrB(nStart, VarArrayBinRequest, sToken)
	End Function

	Private Function ExtractField(sToken, nStart)
		Dim nEnd
		nEnd = InstrB(nStart, VarArrayBinRequest, sToken)
		If nEnd = 0 then
			Response.write "Error in parsing uploaded binary request."
			Response.End
		end if
		ExtractField = String2Byte(MidB(VarArrayBinRequest, nStart, nEnd-nStart))
	End Function

	'String to byte string conversion
	Private Function Byte2String(sString)
		Dim i
		For i = 1 to Len(sString)
		   Byte2String = Byte2String & ChrB(AscB(Mid(sString,i,1)))
		Next
	End Function

	'Byte string to string conversion
	Private Function String2Byte(bsString)
		Dim i
		String2Byte =""
		For i = 1 to LenB(bsString)
		   String2Byte = String2Byte & Chr(AscB(MidB(bsString,i,1))) 
		Next
	End Function
End Class

Class UploadedFile
	Public ContentType
	Public Start
	Public Length
	Public Path
	Private nameOfFile

    ' Need to remove characters that are valid in UNIX, but not in Windows
    Public Property Let FileName(fN)
        nameOfFile = fN
        nameOfFile = SubstNoReg(nameOfFile, "\", "_")
        nameOfFile = SubstNoReg(nameOfFile, "/", "_")
        nameOfFile = SubstNoReg(nameOfFile, ":", "_")
        nameOfFile = SubstNoReg(nameOfFile, "*", "_")
        nameOfFile = SubstNoReg(nameOfFile, "?", "_")
        nameOfFile = SubstNoReg(nameOfFile, """", "_")
        nameOfFile = SubstNoReg(nameOfFile, "<", "_")
        nameOfFile = SubstNoReg(nameOfFile, ">", "_")
        nameOfFile = SubstNoReg(nameOfFile, "|", "_")
    End Property

    Public Property Get FileName()
        FileName = nameOfFile
    End Property

    'Public Property Get FileN()ame
End Class


' Does not depend on RegEx, which is not available on older VBScript
' Is not recursive, which means it will not run out of stack space
Function SubstNoReg(initialStr, oldStr, newStr)
    Dim currentPos, oldStrPos, skip
    If IsNull(initialStr) Or Len(initialStr) = 0 Then
        SubstNoReg = ""
    ElseIf IsNull(oldStr) Or Len(oldStr) = 0 Then
        SubstNoReg = initialStr
    Else
        If IsNull(newStr) Then newStr = ""
        currentPos = 1
        oldStrPos = 0
        SubstNoReg = ""
        skip = Len(oldStr)
        Do While currentPos <= Len(initialStr)
            oldStrPos = InStr(currentPos, initialStr, oldStr)
            If oldStrPos = 0 Then
                SubstNoReg = SubstNoReg & Mid(initialStr, currentPos, Len(initialStr) - currentPos + 1)
                currentPos = Len(initialStr) + 1
            Else
                SubstNoReg = SubstNoReg & Mid(initialStr, currentPos, oldStrPos - currentPos) & newStr
                currentPos = oldStrPos + skip
            End If
        Loop
    End If
End Function
%>

Abhishek Reddy — Mon, 30 May 2005 18:47:50 +0000

Use FileSystemObject.FileExists to check if the file exists. If it does exist, have it trigger your redirection (Response.Redirect or however it is your server or scripts does it). Else, proceed with the upload.
FileExists: http://www.w3schools.com/asp/showfile.asp?filename=demo_fileexists
More on FSO: http://www.w3schools.com/asp/asp_ref_filesystem.asp