Moving files with specific extension to related folders in vb.net - vb.net

Question

I'm using below sub procedure to classify specific files to specific folders but i thought there should be more logic way to do it instead of using so much if elseif structure. I don't know is it true way to do that.
Dim DirInfo As New DirectoryInfo(strPath & "\" & My.Settings.txt_main_db)
For Each SubFile As FileInfo In DirInfo.GetFiles
If Path.GetExtension(SubFile.Name) = ".spck" Or Path.GetExtension(SubFile.Name) = ".buspck" Then
Dim subPathSpck = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_mbs_db_substructure
Directory.CreateDirectory(subPathSpck)
SubFile.MoveTo(subPathSpck & "\" & SubFile.Name)
ElseIf Path.GetExtension(SubFile.Name) = ".fbi" Then
Dim subPathFBI = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_elastic_body
Directory.CreateDirectory(subPathFBI)
SubFile.MoveTo(subPathFBI & "\" & SubFile.Name)
ElseIf Path.GetExtension(SubFile.Name) = ".stl" _
Or Path.GetExtension(SubFile.Name) = ".obj" _
Or Path.GetExtension(SubFile.Name) = ".igs" _
Or Path.GetExtension(SubFile.Name) = ".slp" _
Or Path.GetExtension(SubFile.Name) = ".obj" Then
Dim subPathCAD = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_cad_geometry
Directory.CreateDirectory(subPathCAD)
SubFile.MoveTo(subPathCAD & "\" & SubFile.Name)
ElseIf Path.GetExtension(SubFile.Name) = ".if2" _
Or Path.GetExtension(SubFile.Name) = ".afs" _
Or Path.GetExtension(SubFile.Name) = ".tre" Then
Dim subPathIF2 = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_input_functions
Directory.CreateDirectory(subPathIF2)
SubFile.MoveTo(subPathIF2 & "\" & SubFile.Name)
ElseIf Path.GetExtension(SubFile.Name) = ".subvar" Then
Dim subPathSubVar = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_mbs_db_ip
Directory.CreateDirectory(subPathSubVar)
SubFile.MoveTo(subPathSubVar & "\" & SubFile.Name)
ElseIf Path.GetExtension(SubFile.Name) = ".tpf" _
Or Path.GetExtension(SubFile.Name) = ".tir" Then
Dim subPathDelft = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_tyre_delft_swift
Directory.CreateDirectory(subPathDelft)
SubFile.MoveTo(subPathDelft & "\" & SubFile.Name)
ElseIf Path.GetExtension(SubFile.Name) = ".rdf" Then
Dim subPathRoad = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_mbs_db_road
Directory.CreateDirectory(subPathRoad)
SubFile.MoveTo(subPathRoad & "\" & SubFile.Name)
Else
Dim subPathExt = strPath & "\" & My.Settings.txt_main_db & "\" & My.Settings.txt_mbs_db_extfile
Directory.CreateDirectory(subPathExt)
SubFile.MoveTo(subPathExt & "\" & SubFile.Name)
End If
Next

Answer 1

There is nothing wrong to have some if...elseif.. (or even a Select Case), but if your intent is to remove a lengthy selection you could use a Dictionary where the key is the file extension and the value is a Function that handles that particular key extension.
The key is used to find a Function that configure the variables and do the file move.
This could be done in this way, I leave it to you to judge if this is more clear or not against your current code:
' some test values
Dim strPath As String = "e:\temp"
Dim txt_main_db As String = "root"
Dim txt_mbs_db_substructure = "spkBackup"
Dim txt_elastic_body = "fbiBackup"
' the dictionary
Dim moveHandler As Dictionary(Of String, Action(Of FileInfo))
' initialization somewhere in your code...
Sub Main
' Set the handler for each extensions but you could have the same handler for many extensions
moveHandler.Add(".spck", Function(f As FileInfo) HandleSpck(f))
moveHandler.Add(".buspck", Function(f As FileInfo) HandleSpck(f))
moveHandler.Add(".fbi", Function(f As FileInfo) HandleFbi(f))
......
moveHandler.Add("others", Function(f As FileInfo) HandleOthers(f))
End Sub
' handler to move a file with .spck or .buspck extension
Function HandleSpck(SubFile As FileInfo)
Dim subPathSpck = Path.Combine(strPath,txt_main_db, txt_mbs_db_substructure)
Directory.CreateDirectory(subPathSpck)
SubFile.MoveTo(Path.Combine(subPathSpck,SubFile.Name))
End Function
' handler to move a file with .fbi extension
Function HandleFbi(SubFile As FileInfo)
Dim subPathSpck = Path.Combine(strPath, txt_main_db, txt_elastic_body )
Directory.CreateDirectory(subPathSpck)
SubFile.MoveTo(Path.Combine(subPathSpck, SubFile.Name))
End Function
' Other handlers for other extensions
.....
Finally you can call the handlers with a very short loop
Dim source = Path.Combine(strPath, txt_main_db)
Dim DirInfo As New DirectoryInfo(source)
For Each SubFile As FileInfo In DirInfo.GetFiles
If moveHandler.ContainsKey(SubFile.Extension) Then
moveHandler(SubFile.Extension).Invoke(SubFile)
Else
moveHandler("others").Invoke(SubFile)
End If
Next
But, wait.... now with this code is place it is easy to notate the pattern. You execute always the same code. The only thing that changes is the destination. Now, what if we have an handler where we pass the destination folder and the FileInfo variable? We can have just one handler
Function HandleFileMove(destFolder as String, SubFile As FileInfo)
Dim subFolder = Path.Combine(strPath,txt_main_db, destFolder)
Directory.CreateDirectory(subFolder)
SubFile.MoveTo(Path.Combine(subFolder,SubFile.Name))
End Function
and we have to adjust the dictionary to call always the same handler but giving the new parameter required to create the subfolder.
moveHandler.Add(".spck", Function(f As FileInfo) HandleFileMove(txt_mbs_db_substructure, f))
moveHandler.Add(".fbi", Function(f As FileInfo) HandleFileMove(txt_elastic_body, f))
.....
Of course this is good only if your only task inside the common handler is to copy a file in a predefined subfolder. If you need to do any other task for a specific extension then it is better to have separate handlers for each extension.