Goal: We have windows application built using .Net and this application should be able to retrieve basic information about the user like name, email and his unique parameters like google id etc.

Google Libraries: Google has developed and maintaining libraries as nuget packages for Open Id authentication and services like Google Plus, Google Drive etc.

Note: you can search using “Google.Apis.{google service like plus, drive}”. I am currently using their “Google.Apis.Plus.v1” with version 1.14.0.550

Prerequisites:

1. We need to create an application in Google developer console.
2. Next create Project, Credentials (Client Id, Secret) and enable  necessary API permissions. I have enabled Google + Api

Note: For windows applications client secret is really not a secret, so we really no need to worry keep it in secret place.

Application Changes:

Step 1:

We have all the information need to authenticate our users by using GoogleWebAuthorizationBroker.

var credential = await GoogleWebAuthorizationBroker.AuthorizeAsync(new ClientSecrets() {ClientId = "your client id", ClientSecret = "your client secret" },
new[] {PlusService.Scope.PlusMe, PlusService.Scope.UserinfoProfile, PlusService.Scope.UserinfoEmail}, "me", CancellationToken.None);

Step 2:

After step 1, your application should open browser for user to authenticate and authorize your app to use requested scopes.  Now we use below code to create Person Resource.

Note: Since our app is designed to get currently logged in user, we need to query people resource with id as “me”.


// Create the service.
var service = new PlusService(new BaseClientService.Initializer()
{
HttpClientInitializer = credential,
ApplicationName = "Sample",
});
var peopleResource = service.People.Get("me");
var person = await peopleResource.ExecuteAsync();

Step 3:

Now person object has all the basic information like email, display name, profile url etc.

Happy Coding.