We have been working on a small project using Infopath 2003 and MOSS to create a faster way to input information in a list. Among the challenges (which was quite a few despite it was software from MS on both "sides") faced was how to enable uploading a file while submitting information to a list.
Infopath 2003 provides a
File Attachment Control which enables the end-user to select and attach a file to the form. Infopath automatically encodes the file in Base64 and adds a dynamic header in the front of the file. So we wanted to use the "
AddAttachment" web service available to post the file, one of the parameters is a Base64 encoded string. Great! Well, the header added by Infopath is also included in the encoding. We only have Jscript or VBScript to use in Infopath 2003 if we don´t want to start to deploy extra code on the clients (which I try to prefer to stay away from) and the support for decoding/encoding files in those languages are not to great.
So our solution is to extract the filename from the header (code below) and the attach a list item event receiver for "
ItemAttachmentAdded" which decode the file, removes the header and saves the file again serverside.
Here is the code for extracting the filename from an Infopath Base64 encoded attachment:
dim node
Set node = XDocument.DOM.documentElement.selectSingleNode("/my:myFields/my:FileAttchmentControl")
If(node.text <> "") Then
'typecast the node to base64 as Infopath doesn't do this in node definition
node.DataType = "bin.base64"
'convert base64 node value to binary and store in nodeValue byte array
nodeValue = node.nodeTypedValue
dim convertByteArrayToHexString
convertByteArrayToHexString = ""
For intCounter = 1 to LenB(nodeValue)
convertByteArrayToHexString = convertByteArrayToHexString & Right("0" & Hex(AscB(MidB(nodeValue, intCounter, 1))), 2)
If(intCounter = 100) Then 'Assuming that the header is no longer that 100 bytes
exit for
end if
Next
dim filenameBuffer
dim filename
filename = ""
filenameBuffer = 0
'The length of the filenamebuffer is stored on pos 20-24 (byte), which means 41.47 in Hex and 1 as startpos for Arrays
filenameBuffer = getFilenameBuffer(convertByteArrayToHexString,41,47)
'Read the filename from position (49 to filenamebuffer * unicode - "\n") as end char
filename = getFileName(convertByteArrayToHexString,49,filenameBuffer*4 + 49 - 2)
Function getFilenameBuffer(data,startLoop,stopLoop)
dim k
dim filenameBuffer
for k = startLoop to stopLoop step 2
dim y1
dim y2
dim y3
y1 = Mid(data,k,2)
y2 = CLng("&h" & y1)
y3 = y3 + Int(y2)
filenameBuffer = y3
next
getFilenameBuffer = filenameBuffer
End Function
Function getFileName(data,startLoop, stopLoop)
dim k
dim filename
for k = startLoop to stopLoop step 4
dim h1
dim h2
dim h3
h1 = Mid(data,k,2)
h2 = CLng("&h" & h1)
h3 = Chr(h2)
if(h3 <> "") then
filename = filename & Cstr(h3)
end if
next
getFileName = filename
End Function
