C# Winform app with google Drive API. Way to automate login?

Question

I'm creating a desktop application in C# that will act as a backup program. What I want to do is allow a user to create a schedule for when a backup should happen. I created a windows service that runs in the background that will run based on this schedule.

Right now, my program will copy files that the user has selected to another local user-selected folder. However, I want to extend this to allow users to backup their files to the cloud on a scheduled basis, specifically, their Google Drive account.

I'm not sure if this is possible, though, or how to go about it. I've got code working that will upload files to a Drive account, however, that requires the user to grant permission to my program each and every time it runs. My question is, how can I accomplish this to be done automatically? Is there a way to have a user enter his login credentials once and then allow the program to access their Drive account automatically thereafter, without them having to grant permission every time?

Answer 1

You need to store the access token for your user somewhere and use it to request a new short term access token when you do the backup. From the Google Drive API Docs:

Google Drive applications only receive a long-lived refresh token during the very first exchange of an authorization code. This refresh token is used to request new access tokens after a short-lived access token expires, and it must be stored in the application's database to be retrieved every time the user returns to the app.

See the documentation here for setting up OAuth in your application