I need to get a collection of file names from a folder on a remote server using VBA in excel 2010. I have a function that works and in the majority of cases it would do the job, however the remote server frequently has terrible, terrible network performance issues. This means that looping through say 300 files to put their names into a collection can take 10 minutes, the number of files in the folder is likely to grow to thousands so this is not workable, I need a way to get all of the file names in a single network request and not looping. I believe its connecting to the remote server that is taking the time so a single request should be able to get all of the files in one pass fairly quickly.
This is the function I currently have in place:
Private Function GetFileNames(sPath As String) As Collection
'takes a path and returns a collection of the file names in the folder
Dim oFolder As Object
Dim oFile As Object
Dim oFSO As Object
Dim colList As New Collection
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set oFolder = oFSO.GetFolder(folderpath:=sPath)
For Each oFile In oFolder.Files
colList.Add oFile.Name
Next oFile
Set GetFileNames = colList
Set oFolder = Nothing
Set oFSO = Nothing
End Function
Ok, I have found a solution that works for my situation and perhaps others will find it useful too. This soution uses the windows API and gets me the filenames in 1 second or less where as the FSO method was taking several minutes. It still involves a loop so i'm not certain why it is so much faster but it is.
This takes a path like "c:\windows\" and returns a collection of all the files (and directories) in that folder. The exact parameters I have used require windows 7 or newer, see the comments in the declarations.
'for windows API call to FindFirstFileEx
Private Const INVALID_HANDLE_VALUE = -1
Private Const MAX_PATH = 260
Private Type FILETIME
dwLowDateTime As Long
dwHighDateTime As Long
End Type
Private Type WIN32_FIND_DATA
dwFileAttributes As Long
ftCreationTime As FILETIME
ftLastAccessTime As FILETIME
ftLastWriteTime As FILETIME
nFileSizeHigh As Long
nFileSizeLow As Long
dwReserved0 As Long
dwReserved1 As Long
cFileName As String * MAX_PATH
cAlternate As String * 14
End Type
Private Const FIND_FIRST_EX_CASE_SENSITIVE As Long = 1
'MSDN: "This value is not supported until Windows Server 2008 R2 and Windows 7."
Private Const FIND_FIRST_EX_LARGE_FETCH As Long = 2
Private Enum FINDEX_SEARCH_OPS
FindExSearchNameMatch
FindExSearchLimitToDirectories
FindExSearchLimitToDevices
End Enum
Private Enum FINDEX_INFO_LEVELS
FindExInfoStandard
FindExInfoBasic 'MSDN: "This value is not supported until Windows Server 2008 R2 and Windows 7."
FindExInfoMaxInfoLevel
End Enum
Private Declare Function FindFirstFileEx Lib "kernel32" Alias "FindFirstFileExA" ( _
ByVal lpFileName As String, ByVal fInfoLevelId As Long, lpFindFileData As WIN32_FIND_DATA, _
ByVal fSearchOp As Long, ByVal lpSearchFilter As Long, ByVal dwAdditionalFlags As Long) As Long
Private Declare Function FindNextFile Lib "kernel32" Alias "FindNextFileA" ( _
ByVal hFindFile As Long, lpFindFileData As WIN32_FIND_DATA) As Long
Private Declare Function FindClose Lib "kernel32" (ByVal hFindFile As Long) As Long
Private Function GetFiles(ByVal sPath As String) As Collection
Dim fileInfo As WIN32_FIND_DATA 'buffer for file info
Dim hFile As Long 'file handle
Dim colFiles As New Collection
sPath = sPath & "*.*"
hFile = FindFirstFileEx(sPath & vbNullChar, FindExInfoBasic, fileInfo, FindExSearchNameMatch, 0&, FIND_FIRST_EX_LARGE_FETCH)
If hFile <> INVALID_HANDLE_VALUE Then
Do While FindNextFile(hFile, fileInfo)
colFiles.Add Left(fileInfo.cFileName, InStr(fileInfo.cFileName, vbNullChar) - 1)
Loop
FindClose hFile
End If
Set GetFiles = colFiles
End Function