try this
Private Sub GetFileList(ParentFolder As String)
Authorize() 'Take care of authorization... you could use JS to ask the user and get the Auth Token
'MSO - 20130423 - Search the Google Drive File with the specified foldername
'Create the search request
Dim oListReq As Google.Apis.Drive.v2.FilesResource.ListRequest
Dim oFileList As FileList
'mimeType = 'application/vnd.google-apps.folder'
oListReq = oDriveService.Files.List()
'Search for a specific file name
oListReq.Q = "mimeType = 'application/vnd.google-apps.folder' and title = '" + ParentFolder + "' and trashed=false"
oListReq.Fields = "items/id" 'MSO - 20130621 - only ID needed for next query
oListReq.MaxResults = 10 'Max 10 files (too may I Expect only 1)
'Get the results
oFileList = oListReq.Fetch()
'Only 1 result is expected
If oFileList.Items.Count = 1 Then
Dim oFile As File = oFileList.Items(0)
FolderId = oFile.Id 'Get FolderId
End If
oListReq = oDriveService.Files.List()
'Search for a specific file name in the folder
oListReq.Q = "'" + FolderId + "' in parents and trashed=false "
'oListReq.Fields = "items(id,alternateLink)" 'MSO - 20130621 - Optimize your query if you need only certain fields
'Get the results
oFileList = oListReq.Fetch()
'TODO: oFileList now have the list of the files in the folder, but there could me more "pages"
End Sub