Question

Loading an XLS file is a bit of a pain for a quick app we’re throwing together (we know about how to do that but it’s not worth the time especially in C++) so we’re going to take the simple approach of have the user export a CSV copy. However to save them the trouble I wondered if we can have a macro which will automatically save a CSV version whenever they save the XLS(X) in Excel 2007?

Update:
Following Timores’ answer, I dug in a bit and came up with this:

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
    Dim Sourcewb As Workbook
    Dim Destwb As Workbook
    Dim TempFileName As String

    With Application
        .ScreenUpdating = False
        .EnableEvents = False
    End With

    Set Sourcewb = ActiveWorkbook
    TempFileName = Sourcewb.FullName + ".csv"

    'Copy the sheet to a new workbook
    ActiveSheet.Copy
    Set Destwb = ActiveWorkbook

    'Save the new workbook and close it
    With Destwb
        .SaveAs Filename:=TempFileName, FileFormat:=xlCSV, ConflictResolution:=xlLocalSessionChanges
        .Close SaveChanges:=False
    End With

    With Application
        .ScreenUpdating = True
        .EnableEvents = True
    End With
End Sub

This works except I can’t make it force-save the CSV, rather than asking me if I want to overwrite, even after adding ConflictResolution:=xlLocalSessionChanges

Answer 1

Original version:

In the VB editor part of Excel, select “ThisWorkbok” in the left navigation menu. In the editor on the right, select Workbook on the left drop-down, and BeforeSave on the right one.

Replace the macro by:

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)

    ActiveWorkbook.SaveCopyAs ActiveWorkbook.FullName + ".csv"
End Sub

This will make a copy with the CSV extension.

Please note that an XLSX file cannot have a macro (you need an XLSM extension, or the older XLS one) and that users will need to have a medium or low level of security in order for the macro to run (or you have to sign the document).

Edited version:

I tested it again, after seeing the comments below. Strangely enough, it did not work like it did the first time. Here is a fixed version. Again, in the ‘This Workbook’ part of the macro editor:

Dim fInSaving As Boolean

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)

If fInSaving Then
    Exit Sub
End If

fInSaving = True

Dim workbookName As String
Dim parentPath As String
Dim fs As Object
Set fs = CreateObject("Scripting.FileSystemObject")

If SaveAsUI Then

    Dim result
    result = Application.GetSaveAsFilename

    If VarType(result) = vbBoolean Then
        If CBool(result) = False Then
            Exit Sub ' user cancelled the dialog box
        End If
    End If

    workbookName = fs.GetFileName(result)
    parentPath = fs.GetParentFolderName(result)
Else

    workbookName = ActiveWorkbook.name
    parentPath = ActiveWorkbook.path
End If


Dim index As Integer
index = InStr(workbookName, ".")

Dim name As String
name = Left(workbookName, index - 1)

' extension can be empty is user enters simply a name in the 'File / Save as' dialog
' so it is not computed (but hard-coded below)

' do not ask for confirmation to overwrite an existing file
Application.DisplayAlerts = False

' save a copy
ActiveWorkbook.SaveAs fs.BuildPath(parentPath, name & ".csv"), XlFileFormat.xlCSV

' Save the normal workbook in the original name
ActiveWorkbook.SaveAs fs.BuildPath(parentPath, name & ".xlsm"), XlFileFormat.xlOpenXMLWorkbookMacroEnabled
Cancel = True

Application.DisplayAlerts = True
fInSaving = False
End Sub

Private Sub Workbook_Open()

    fInSaving = False
End Sub

What is surprising is that calling ActiveWorkbook.SaveAs triggers the macro again => the global boolean to prevent infinite recursion.