BaseClient's HttpClientInitializer property is private set, making it impossible to change cred after client is initialized, forcing unneeded recreations. Any workaround?

[mikequ-taggysoft]

We have stored users tokens (both access and refresh) in our database and handle our own refresh logic. So we use GoogleCredential.FromAccessToken to authenticate the clients.

I'm trying to implement DI pattern for various clients (CalendarService, GmailService etc) as they're used a lot within the same class across many methods. DI would make them reusable and easy to manage.

However, the HttpClientInitializer can only be set at construction time. The problem is that our service layer codes all use DI. It is not possible for us to set user at DI constructor injection time, so we need to rely on user IDs etc passed to our service methods to retrieve the correct users' tokens and set the credentials on these clients.

Because HttpClientInitializer cannot be set after client creation, it forces us to recreate clients repeatedly.

I suspect this design may have something to do with thread safety, but since Google has batch support, I don't think running multiple clients in parallel is a good pattern, especially considering the fact that Google has various limits on per user/api/project calls.

Is there a way to make DI work in my scenario?

Would you consider making the HttpClientInitializer property public settable?

It's a bit of a pain as we're trying to build a service that works with both MS Graph and Google, and MS's GraphServiceClient doesn't have such a restriction, so we have to treat the Google side differently. 😄

[amanda-tarafa]

You can use per-request credentials as follows without the need to change the credential on the service client (pardon possible typos). I believe this should cover your use case.

// From DI, no credential set. Or also a default credential set if you need to.
CalendarService client;
GoogleCredential credential = GoogleCredential.FromAccessToken(GetAccessToken(userId)); 
// Create a request with a per-call credential.
var request = client.Events.List(....).AddCredential(credential);
// If a request has a credential set, then the client service credential is ignored.
var events = request.Execute();

[mikequ-taggysoft]

@amanda-tarafa Ahhh I kept looking for a method like this on the client level, somehow never thought of looking at the ClientServiceRequest level. All makes sense now. Thank you!!