[AccessD] ZIpping Files

Wow, is that cool or what!  Now all we need is a version checker or some other method to determine 
if this is valid on the current OS.

John W. Colby
www.ColbyConsulting.com


Stuart McLachlan wrote:
> There has just been a discussion over on dba-Tech about the built in Zip capabilities in 
> Windows (XP onwards?) where "Compressed (zipped) Folders" are just ordinary zip files.
> 
> This  got me thinking about how you could use the built in capabilities to manage zip files  
> through VBA rather than needing a third party DLL, the Winzip CLI or whatever.
> 
> Turns out it is trivial to to create an empty ZIp file, it is just a string of 22 bytes as follows:
> 
> Function CreateNewZipFolder(Filename As String) As Long
> Dim strEmptyZip As String
> strEmptyZip = Chr$(80) & Chr$(75) & Chr$(5) & Chr$(6) & String$(18, Chr$(0))
> Open Filename For Binary As #1
> Put #1, , strEmptyZip
> Close #1
> End Function
> 
> You can now use a Shell.Application object to work with this file/folder.
> 
> Firstly set a reference to  Microsoft Shell Controls and Automation:  Shell32.dll
> 
> Then you just need a couple of simple functions:
> 
> Function AddFileToZip(ZipFileName As String, Filename As String)
> 'Zipfilename and Filename need to be full paths
>   Dim oShellApp As Shell32.Shell
>   Set oShellApp = CreateObject("Shell.Application")
>   oShellApp.NameSpace(ZipFileName).CopyHere Filename
>   Set oShellApp = Nothing
> End Function
> 
> and
> 
> Function ExtractFileFromZip(ZipFileName As String, DestDir as String,Filename As String)
> 'Zipfilename and DestDir need to be full paths
> 'Filename should just be the filename without a path
>   Dim oShellApp As Shell32.Shell
>   Set oShellApp = CreateObject("Shell.Application")
>   oShellApp.NameSpace(DestDir).CopyHere _         
> oShellApp.Namespace(ZipFileName).Items.Item(Filename)
>   Set oShellApp = Nothing
> End Function
> 
> To extract all files replace
> oShellApp.Namespace(ZipFileName).Items.Item(Filename)
> with
> oShellApp.Namespace(ZipFileName).Items
> 
> Note that this is a bare shell and you will need to add a bit of error checking - oShellApp 
> doesn't like it if files/directories don't exist and will pop up a standard "File exists, do you 
> want to copy" dialog if the zip or destination already contains the file.
>