Save information immediately after Google login in Azure Mobile Services (.NET Back-end) - authentication

Question

What I basically want to be able to do is authenticate to azure mobile services (using google or some other provider), and immediately save some of the user information (i.e. email address) on the server.
I know I could call a custom method from the app after authentication, but I was hoping to have some hook to do this straight after the google login on the server side.
Is this possible? How do I do it?!

Answer 1

This is currently only possible in the .NET runtime. If using the Node runtime, you will not be able to do this.
For the .NET runtime, you would want to create a class which inherits from GoogleLoginProvider (I'll call mine CustomGoogleLoginProvider), and then you'll need to override the CreateCredentials method:
public override ProviderCredentials CreateCredentials(ClaimsIdentity claimsIdentity)
{
// grab any information from claimsIdentity which you would like to store
// If you need the access token for use with the graph APIs, you can use the following
string providerAccessToken = claimsIdentity.GetClaimValueOrNull(ServiceClaimTypes.ProviderAccessToken);
// use the access token with HttpClient to get graph information to store
return base.CreateCredentials(claimsIdentity);
}
Then in your WebApiConfig.cs, add the following to the Register() method, immediately after the options object is created:
options.LoginProviders.Remove(typeof(GoogleLoginProvider));
options.LoginProviders.Add(typeof(CustomGoogleLoginProvider));
The CreateCredentials() method gets called immediately before a Mobile Services token is created. At this point, the Google token has been validated, and the claimsIdentity has been populated with whatever Google sent back.
Some information will be available in the claimsIdentity by default, but you may also have information which requires you to call through to Google. You can only do this if you set the proper scopes configured.
If you did want to go the custom API route, you would just need to make a call from your controller:
ServiceUser user = (ServiceUser)this.User;
GoogleCredentials creds = (await user.GetIdentitiesAsync()).OfType<GoogleCredentials>().FirstOrDefault();
string accessToken = creds.AccessToken;
The Node version of getIdentities() is documented here.