Prevent duplicate folder creation in Google Drive using C#

Other Questions Google drive
1

I need help with my C# application that connects to Google Drive API. Every time I run my program, it makes a new folder with the same name instead of using the existing one.

class DriveManager
{
    private string[] ApiScopes = { DriveService.Scope.Drive };
    private string AppName;
    private string DirectoryId;
    private string DocumentName;
    private string DocumentPath;
    private string FileType;

    public DriveManager(string docName, string docPath)
    {
        AppName = "DataUploader";
        FileType = "text/csv";
        DocumentName = docName;
        DocumentPath = docPath;
    }

    public void StartUpload()
    {
        UserCredential creds = AuthenticateUser();
        DriveService driveClient = InitializeDriveService(creds);
        DirectoryId = MakeDirectory(driveClient, "ReportsFolder");
        UploadDocument(driveClient, DocumentName, DocumentPath, FileType);
    }

    private DriveService InitializeDriveService(UserCredential creds)
    {
        return new DriveService(new BaseClientService.Initializer()
        {
            HttpClientInitializer = creds,
            ApplicationName = AppName,
        });
    }

    private UserCredential AuthenticateUser()
    {
        UserCredential userCreds;
        using (var fileStream = new FileStream("credentials.json", FileMode.Open, FileAccess.Read))
        {
            string credsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
            credsPath = Path.Combine(credsPath, ".auth/drive-app.json");

            userCreds = GoogleWebAuthorizationBroker.AuthorizeAsync(
                GoogleClientSecrets.Load(fileStream).Secrets,
                ApiScopes,
                "user",
                CancellationToken.None,
                new FileDataStore(credsPath, true)).Result;
        }
        return userCreds;
    }

    private string UploadDocument(DriveService client, string docName, string docPath, string mimeType)
    {
        var docMetadata = new Google.Apis.Drive.v3.Data.File();
        docMetadata.Name = docName;
        docMetadata.Parents = new List<string> { DirectoryId };

        FilesResource.CreateMediaUpload uploadRequest;
        using (var fileStream = new FileStream(docPath, FileMode.Open))
        {
            uploadRequest = client.Files.Create(docMetadata, fileStream, mimeType);
            uploadRequest.Upload();
        }
        var uploadedFile = uploadRequest.ResponseBody;
        return uploadedFile.Id;
    }

    public static string MakeDirectory(DriveService client, string dirName)
    {
        bool folderExists = CheckIfExists(client, dirName);
        if (folderExists)
            return $"Directory {dirName} is already there!";

        var newFolder = new Google.Apis.Drive.v3.Data.File();
        newFolder.Name = dirName;
        newFolder.MimeType = "application/vnd.google-apps.folder";
        var createRequest = client.Files.Create(newFolder);
        createRequest.Fields = "id";
        var response = createRequest.Execute();
        return response.Id;
    }

    private static bool CheckIfExists(DriveService client, string folderName)
    {
        var searchRequest = client.Files.List();
        searchRequest.PageSize = 100;
        searchRequest.Q = $"trashed = false and name contains '{folderName}' and 'root' in parents";
        searchRequest.Fields = "files(name)";
        var foundFiles = searchRequest.Execute().Files;

        foreach (var foundFile in foundFiles)
        {
            if (folderName == foundFile.Name)
                return true;
        }
        return false;
    }
}

The issue is that my folder checking logic does not work properly. Can someone tell me what I am doing wrong? I want to reuse the same folder if it exists instead of making duplicates.

2

Your CheckIfExists method only returns true/false but doesn’t give you the folder ID when it finds one. That’s the issue. Instead of returning a boolean, make it return the actual folder ID (or null if nothing’s found). When I hit this same problem, I rewrote the method to return the ID directly. Then in MakeDirectory, just check if you got null back before creating a new folder. Also, add the folder mime type to your query so it doesn’t match files with the same name: “trashed = false and name = ‘{folderName}’ and mimeType = ‘application/vnd.google-apps.folder’ and ‘root’ in parents”. I switched ‘contains’ to ‘=’ for exact matching too.

3

your MakeDirectory method returns a string message when it finds an existing folder, not the actual folder ID. that’s why it keeps making new ones. just return the folder ID instead of the text message.

4

Your MakeDirectory method is mixing up return types - it sends back a string message when a folder exists, but UploadDocument expects an ID. That’s what’s breaking things.

Here’s the fix: Make CheckIfExists return the actual folder ID when it finds a match, and null when it doesn’t. Then MakeDirectory just needs to check if you got null back before creating anything new.

Also, switch that ‘contains’ in your search query to ‘=’ - otherwise you’ll match folders with similar names instead of exact matches.