Getting AppData\Local folder

Targets Windows
1

Need to read a file that’s in AppData\Local.

SpecialFolder.ApplicationData returns the Roaming variant of AppData.

I realize I could use SpecialFolder.ApplicationData.Parent.Child(“Local”) but this is not the guaranteed path on every system.

Is there another SpecialFolder method that yields the Local AppData folder?

2

So apparently the Local AppData path is stored in the registry under \HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\Local AppData

But then the problem becomes that the paths can contain any environment variable (for example %USERPROFILE%) so now you need to resolve every one of those, make the string replacement, then cast it into a FolderItem. This is also complicated by the fact that something like “%USERPROFILE%” is both a possible environment variable or a valid folder name.

There has to be a simpler way as this seems as if it would be basic functionality.

3

For now, I’m using:

dim AppDataLocal as new folderitem(system.EnvironmentVariable("LocalAppData"))

But if someone knows a better way, please chime in, because that’s reliant on an Environment Variable that should be present, but doesn’t have to be.

4

You could grab the registry value and use a shell to cd to it then pwd to get the resolved path.

1 Like
5

Thanks for that! This got me thinking. I ended up putting this batch file together:

@for /f "tokens=4" %%a in ('reg query "HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders"  /V "Local AppData"  ^|findstr /ri "REG_EXPAND_SZ"') do @call echo %%a

And turned it into a Xojo function.

Private Function AppDataLocal() As FolderItem
  #If TargetWindows
    
    dim s as new shell
    s.execute("@for /f " + Chr(34) + "tokens=4" + Chr(34) + " %a in ('reg query " + Chr(34) + "HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" + Chr(34) + "  /V " + Chr(34) + "Local AppData" + Chr(34) + "  ^|findstr /ri " + Chr(34) + "REG_EXPAND_SZ" + Chr(34) + "') do @call echo %a")
    return new folderItem(s.result.trim)
    
  #Else
    
    return SpecialFolder.ApplicationData
    
  #EndIf
End Function

This works! Thanks again for the inspiration.

6

It is documented by Microsoft that you should not rely on those values in the registry. Your approach reading the environment variable it probably the more reliable approach.

A better approach would be to use the Win32 API SHGetKnownFolderPath function with the corresponding KNOWNFOLDERID using a declare in Xojo.

7

Maybe this code snippet will help:

    Const CSIDL_LOCAL_APPDATA = &h1c
  
    Declare Function SHGetSpecialFolderPathA Lib "Shell32" (hwnd As Integer, pszPath As Ptr, csidl As Integer, fCreate As Boolean) As Boolean
    
    Var oSpace As New MemoryBlock(1024)
    Var pSpacePtr As Ptr = oSpace
    
    If SHGetSpecialFolderPathA(0, pSpacePtr, CSIDL_LOCAL_APPDATA, False) Then
      Var sPath As String
      sPath = oSpace.CString(0)
      Return New FolderItem(sPath, FolderItem.PathModes.Native)
    End If
8

This should work:

Var localAppData As FolderItem = SpecialFolder.Temporary.Parent
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9

Just by curiosity; why do you need to read that file ?

10

@Stefan_Roth1 Thank you for that! I believe you are correct that this is the “correct” way to retrieve it. @Rick_Araujo’s workaround is absolutely brilliant too, after a bit of research it turns out that the Temporary folder is always part of the local Appdata.

@Michel_Bujardet I am interfacing with another piece of software that writes its configuration file to a subfolder of LocalAppData.

11

Ask Stefan to rewrite that solution using the current SHGetKnownFolderPath instead of the legacy SHGetSpecialFolderPathA so it can be safer/proper for international users with unicode string paths.

That’s why I opted for using the shorter Xojo native option.

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