Re: VBA code to decode Base64 Infopath attachment from a form.

Leandro Figueira — Tue, 06 Sep 2016 17:31:04 GMT

Please , you could decode a base64 file InfoPath XML form?

Re: VBA code to decode Base64 Infopath attachment from a form.

dcdc700 — Tue, 26 Jan 2016 22:05:52 GMT

Hello,

I'm trying to extract attachments from InfoPath forms (xml files), base64 string and was trying to use this, but I'm not much of a coder so need some assistance if possible. Does this work with Office 2013 dev tools (word)? I tried using PowerShell but for some reason the decode isn't working so I found this code... thanks in advance.

VBA code to decode Base64 Infopath attachment from a form.

Skarn — Wed, 24 Dec 2008 09:51:16 GMT

Hi,

I have put together an example function which is VBA and I have used in my VBA applications. It seems to (I haven't done extensive testing) decode infopath attachment fields from an Infopath xml form successfully. I use Infopath 2003 and Microsoft Office 2003 Professional

I don't use this code inside form templates themselves, I use in programs like Microsoft Access - but maybe with this you can adapt to your need.

In Microsoft Access under the Visual Basic editor, I first had to go to Tools menu -> references and tick to add Microsoft XML v2.0 as a reference.

Then make a new code module and paste the code into it in it's entirety

Then use the extractAttachment(strFileName, strXPath, strOutputFolder) function to save a file which is the attachment from the Infopath form specified.

You will need to specify the xPath to the field in strXPath.

I have commented to the code as best I can to show understanding of what it is doing and how it works. I had to deduce the function by reading numerous posts around the net to try and work out a working method - all seemed to be in C or other languages and were outside my scope to use - but finally after much experimenting and inching closer and closer to the answer te below code is made. I learnt about byte arrays and binary file creation as well as getting access to the XML object model through VBA.

I think this will be useful for many. Good luck!

'Infopath file attachment extraction Module
'by Ryan Marshall
'
'compiled from numerous web sources and trial and error to make a functional extraction routine.
'Methods:
'   extractAttachment(strFormFileName,strXPath,strOutputFolder)
'   strFormFileName = filepath to form to extract attachment from
'   strXPath = xPath expression to field which to extract attachment from (single Node only)
'   strOutputFolder = folderpath to folder where to save extracted attachment to (with terminating "\")

'Custom data types
'for Byte array to Long (number) conversion
Private Type LongByteType
    b1 As Byte
    b2 As Byte
    b3 As Byte
    b4 As Byte
End Type

Private Type LongType
l As Long
End Type

Private LongRec As LongByteType
Private MyLong As LongType
Public Sub extractAttachment(strFileName, strXPath, strOutputFolder)
    Dim iFile As Integer                'binary file number index
    Dim oNode As IXMLDOMNode            'base64 data node from form field
    Dim nodeValue() As Byte             'full byte array of base64 data
    Dim fileContent() As Byte           'byte array of file data only
    Dim arrFileNameSize(4) As Byte      'byte array of file size only
    Dim arrFileName() As Byte           'byte array of filename only
    Dim arrFileData() As Byte
    Dim oDoc As DOMDocument             'XML document object to load form into

    'create XML document in memory
    Set oDoc = New DOMDocument
    'load form into XML document in memory
    If oDoc.Load(strFileName) = True Then
        If Not (oDoc Is Nothing) Then
            'read attachment node value to oNode object
            Set oNode = oDoc.documentElement.selectSingleNode(strXPath)
            'typecast the node to base64 as Infopath doesn't do this in node definition
            oNode.DataType = "bin.base64"
            'convert base64 node value to binary and store in nodeValue byte array
            nodeValue = oNode.nodeTypedValue

            'read filesize from byte position 20 (4 bytes) to byte array
            For i = 20 To 24
                arrFileNameSize(i - 20) = nodeValue(i)
            Next

            'convert filesize byte array to actual file length (and multiply by 2 to get length in bytes)
            fileNameSize = ByteArraytoLong(arrFileNameSize) * 2

            'now we know how many bytes the filename is read in filename bytes in filename byte array
            '(filename starts at 24 and goes for filesize*2 bytes)
            ReDim arrFileName(fileNameSize - 1)
            For i = 24 To 23 + fileNameSize
                arrFileName(i - 24) = nodeValue(i)
            Next

            'convert filename byte array to filename string (vba takes care of typecasting here)
            strFileName = Trim(arrFileName)

            'calculate filecontent byte length (equals full byte size of field - header data (default and filename))
            headerLength = 24 + fileNameSize
            fileDataLength = UBound(nodeValue) - headerLength

            'now make room in fileData byte array equal to this size
            ReDim arrFileData(fileDataLength)
            'store the byte data for the file in the fileData byte array
            For i = headerLength To UBound(nodeValue)
                arrFileData(i - headerLength) = nodeValue(i)
            Next

            'open up output binary file
            iFile = FreeFile()
            strOutputFileName = strOutputFolder & strFileName
            Open strOutputFileName For Binary Access Write As iFile

            'output entire fileContent byte array to file
            Put iFile, , arrFileData
            Close iFile
        End If
    End If
End Sub

'Byte array to Long conversion function using custom Types
Public Function ByteArraytoLong(pArray As Variant) As Long
    LongRec.b1 = pArray(0)
    LongRec.b2 = pArray(1)
    LongRec.b3 = pArray(2)
    LongRec.b4 = pArray(3)

    LSet MyLong = LongRec

    ByteArraytoLong = MyLong.l
End Function

Code

Re: VBA code to decode Base64 Infopath attachment from a form.

Re: VBA code to decode Base64 Infopath attachment from a form.

VBA code to decode Base64 Infopath attachment from a form.