Google Drive SDK - Populate .NET TreeView with Google Drive directory structure - treeview

Question

I'm building a VB.NET Google Drive file explorer application for reasons that you probably do not care about. I'm using the google drive v2 sdk, and I'm trying to populate a tree view control with a user's entire Google Drive directory structure (not files, just folders.) My code is working fine, however, as I feared, it is taking several minutes for users that have a whole lot of nested folders. I am using a background worker thread to populate the treeview using a delegate function. Can anyone suggest a more efficient way of doing this?
NewPopulate() is called from my code to create the background worker threads. Start here:
Private Sub NewPopulate()
TreeView1.Nodes.Add(ActiveUser.Email, ActiveUser.Email)
bwPopulateTree = New BackgroundWorker
AddHandler bwPopulateTree.DoWork, AddressOf PopulateTreeStart
AddHandler bwPopulateTree.RunWorkerCompleted, AddressOf PopulateTreeFinished
bwPopulateTree.RunWorkerAsync()
cmbActiveUsers.Enabled = False
End Sub
Private Sub PopulateTreeStart()
Dim children As ChildList = FileManager.GetFoldersInFolder(ActiveUser.DriveService, "root")
PopulateTreeLoop(ActiveUser.Email, children)
End Sub
Private Sub PopulateTreeFinished()
lblToolStripStatus.Text = "Directory listing completed."
SaveTree()
cmbActiveUsers.Enabled = True
End Sub
Private Sub PopulateTreeLoop(nodeKey As String, ByVal childList As ChildList)
If Not childList Is Nothing Then
Dim user As GoogleUser = ActiveUser
For Each child As ChildReference In childList.Items
Dim successful As Boolean = False
If TreeView1.InvokeRequired Then
successful = TreeView1.Invoke(New m_FindAddNode(AddressOf FindAddNode), {nodeKey, child})
Else
successful = FindAddNode(nodeKey, child)
End If
Dim children As ChildList = FileManager.GetFoldersInFolder(user.DriveService, child.Id)
If Not children Is Nothing Then
PopulateTreeLoop(child.Id, children)
End If
Next
End If
End Sub
Private Function FindAddNode(nodeKey As String, child As ChildReference) As Boolean
'Returns true if successful
Try
Dim service As DriveService = ActiveUser.DriveService
Dim file As Drive.v2.Data.File = service.Files.Get(child.Id).Fetch()
Dim node() As TreeNode = TreeView1.Nodes.Find(nodeKey, True)
Dim strTitle As String
If file.FileExtension Is Nothing Then
strTitle = file.Title
Else
strTitle = If(file.Title.EndsWith(file.FileExtension), file.Title, file.Title + file.FileExtension)
End If
node(0).Nodes.Add(file.Id, strTitle)
Return True
Catch ex As Exception
Return False
End Try
End Function
And here is my FileManager class function:
Public Shared Function GetFoldersInFolder(service As DriveService, ByVal folderId As String) As ChildList
Dim request As Google.Apis.Drive.v2.ChildrenResource.ListRequest = service.Children.List(folderId)
request.Q = "mimeType='application/vnd.google-apps.folder'"
Return request.Fetch()
End Function
Sorry I had to include so much code, but I tried to include only that which is necessary. I also already have code which allows me to cache the directory structure, but decided it will be hard to implement, since I will have to be checking to make sure things haven't changed... I really just need a faster way of retrieving the directory structure. I know another way of doing this is to have the treeview only populate the subfolders once a user clicks on the parent folder, but I would like to avoid the short pause which comes from waiting for the server to respond to each request, every time the user clicks on a new folder.
I also have a function which retrieves ALL folders:
Public Shared Function GetAllFolders(service As DriveService) As FileList
Dim request As Google.Apis.Drive.v2.FilesResource.ListRequest = service.Files.List
Dim request2 As Google.Apis.Drive.v2.FilesResource.ListRequest = service.Files.List
request.Q = "mimeType='application/vnd.google-apps.folder'"
Return request.Fetch()
End Function
But I can't come up with any efficient way to parse that list to come up with a directory structure... Any ideas? I really appreciate the help. I've been working on this for days...

Answer 1

Your method is reasonable. Sorry it is taking a long time with large Google Drives. I certainly think that you are on the right idea in only populating the child nodes when the user attempts to expand the parent. The pause there is expected, but you can mitigate it somewhat by displaying some feedback to the user, e.g. Loading....
In this age of cloud computing, users expect some delay when loading data from a remote service. This will improve in the future as network speeds improve.