Dfyjkt

Lets say the user already has files synchronized (via my app) to their Drive folder. Now they sign into my app on a second device and is ready to sync files for the first time. Do I use the Changes API for the initial sync process?

I ask because using the Changes API requires a StartPageToken, which requires that there had been a previous sync operation. Well there is no possible way for user to already have a StartPageToken if they are synchronizing data on a device for the first time.

Google's documentation is a joke. They shouldn't leave it up to us to read between the lines and just figure this out. I'm sure I can cook up something that will "work", but how do I ever know that it is the "appropriate" and EFFICIENT way to go about handling this?

public async Task<AccessResult> GetChangesAsync(CancellationToken cancellationToken, string fields = "*")

 ChangesResource.ListRequest listRequest = new ChangesResource.ListRequest(DriveService, startPageToken)
 
 Spaces = Folder_appDataFolder,
 Fields = fields + ", nextPageToken",
 IncludeRemoved = true,
 PageSize = 20
 ;

 ChangeList changeList = await listRequest.ExecuteAsync(cancellationToken);

Here, I am looking to start syncing the user's for the first time and so a page token doesn't even make sense for that because during the first sync your goal is to get all of the users data. From then on you are looking to only sync any further changes.

One approach I thought of is to simply use ListRequest to list all of the users data and start downloading files that way. I can then simply request a start page token and store it to be used during sync attempts that occur later...

...But what if during the initial download of the user's files (800 files, for example) an error occurs, and the ListRequest fails on file 423? Because I cannot attain a StartPageToken in the middle of a ListRequest to store in case of emergency, do I have to start all over and download all 800 files again, instead of starting at file 423?

When doing changes.list for the first time you should call getStartPageToken this will return the page token you can use to get the change list. If its the first time then there will be no changes of course.

If the user is using your application from more then one device then the logical course of action would be for you to save the page token in a central location when the user started the application for the first time on the first deceive. This will enable you to use that same token on all additional devices that the user may chose to use.

This could be on your own server or even in the users app data folder on drive

I am not exactly user what your application is doing but i really dont think you should be downloading the users files unless they try to access it. There is no logical reason i can think of for your application to store a mirror image of a users drive account. Access the data they need when they need it. You shouldn't need everything. Again i dont know exactly what your application does.