带有服务帐户问题的Google Contacts API

Question

So, I've basically got this working, except for one issue. I've got a google service account set up so it can access our domain contacts. And it can batch query them perfectly!

But if I call cr.Retrieve("some-contact-url-here"), it throws an error griping about not having a Refresh token. I'm using a service account though, so I don't get a refresh token when I authenticate.

And I can't seem to find any good answer as to how I'm supposed to get a refresh token for a service account. There's one or two stackoverflow posts which actively mention getting a refresh token with a service account....but what they linked to has since been redirected. Anything else I've found to do with refresh tokens has basically been about authenticating manually and storing the token. Because I need to use a Service Account, that is not a possibility.

Answer 1

A service account's credentials, which you obtain from the Google Developers Console, include a generated email address that is unique, a client ID, and at least one public/private key pair. You use the client ID and one private key to create a signed JWT and construct an access-token request in the appropriate format. Your application then sends the token request to the Google OAuth 2.0 Authorization Server, which returns an access token. The application uses the token to access a Google API. When the token expires, the application repeats the process.

Check this page for more information.

Answer 2

Ok, based on several hours of bashing my head violently against the API, it looks like there's basically no way to get a refresh token when you're authenticating as a Service Account. Expected behavior, really.

Anyway, to get around the issue, you can load all of the contacts into memory,

feed.AutoPaging = true;
foreach (var c in feed.Entries)
{
    contactList.Add(c);
}

And you can update|delete|etc then. Grossly inefficient though. Especially if your contact list gets rather big.