Google Drive .Net API. No metadata for files available

Question

I'm trying to get Folders and Files from Google Drive, and there is some non-obvious stuff I can't understand.

First of all, I'm getting 37 items as a result - and that's wrong, because I never had 37 files on my Drive, so where all those files came from ?

Second, I'm not receiving file metadata like "Size" or "Extension" or "Parents" - all these properties are "null" for at least half of all items returned - can someone explain what means is "Parents" are "null"?

And the last thing, can I get files and folders step-by-step, like in OneDrive, e.g., get all files and folders from root of a drive, and later get children from selected folder (or download item if it's file)?

As far as I know, I have to get all files and folders and then build a tree to show it to user, as for me that's not good, because of multi-parenting stuff etc.

Here's code I use to get files and properties:

public UserCredential Authorize()
{
    UserCredential credential = null;

    using (var stream =
            new FileStream("path_to_secret.json", FileMode.Open, FileAccess.Read))
    {
        string credPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
        credPath = Path.Combine(credPath, "path_to_save_creds.json");

        credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                GoogleClientSecrets.Load(stream).Secrets,
                Scopes,
                "user",
                CancellationToken.None,
                new FileDataStore(credPath, true)).Result;
    }

    return credential;
}

public List<File> RetrieveAllFiles(DriveService service)
{
    List<File> result = new List<File>();
    FilesResource.ListRequest request = service.Files.List();
    request.Fields =
            "nextPageToken, files(name, id, size, kind, parents, sharedWithMeTime, shared, sharingUser, fileExtension, viewedByMe, viewedByMeTime, trashed)";
    request.Spaces = "drive";

    do
    {
        try
        {
            FileList files = request.Execute();

            result.AddRange(files.Files);
            request.PageToken = files.NextPageToken;
        }
        catch (Exception e)
        {
                  /*handle exception here*/
        }
    } while (!String.IsNullOrEmpty(request.PageToken));
    return result;
}

Here's how do I call methods described above:

UserCredential credential = Authorize();

var service = new DriveService(new BaseClientService.Initializer()
{
        HttpClientInitializer = credential,
        ApplicationName = ApplicationName,
});
var googleFiles = RetrieveAllFiles(service);

At this point, I have 37 items, and such properties as "fileExtension", "viewedByMe", "parents" are null. Can someone explain what happens?

Mr.Rebot Mr.Rebot · Accepted Answer · 2016-12-27T14:10:58

First, you might want to check how your authorization to see who's account is being accessed.

Second, try checking the OAuth 2.0 Playground as suggested in the related SO post to test whether something wrong in your code or in the API. Also stated in the post that files like folders, Google Docs which are simply links will be null.

For the Tree Command like function for your Google Drive, it will all depend on how your approach is. I found a tutorial using Apps Script which will show the basic steps on getting a hierarchical tree diagram for your Drive files.

Hope this helps.

Google Drive .Net API. No metadata for files available

1 Answers