Using Google APIs from Console apps in .NET

I have noticed a common and recent issue that developers have been having with the Google APIs has been building out console apps. In this post I’ll give you a few short demos for API calls and authorization. The following screenshot shows the token verification demo running from the console:

dotnet_console_app

 

 

Running the Demo Solution / Projects

The demo for these console apps is available from my GitHub account. To clone the project from your console, just run:

git clone https://github.com/gguuss/google-dotnet-demo

From your GitHub shell.

After you have cloned the project, open the solution file, GoogleDotNetDemo.sln. Right click on the solution, select restore NuGet packages, and then press F5 to try running the apps. If everything worked correctly, the app should build and you will see the default app, the token verification demo, start running.

Demo of Simple API Calls: Token Verification from Console

The first example I’m going to show is a console app that performs Google OAuth 2 token verification. This is the most concise demo I could come up with and it’s actually useful if you want to check your access tokens during debugging.

First, set up your project from the NuGet package manager interface in Visual Studio, add Google.Apis.Oauth2.v2.

The following code is the full source of the app’s main function:

        private static void Main(string[] args)
        {
            Console.WriteLine(@"Input an Access token:");
            String accessToken = Console.ReadLine();

            Oauth2Service service = new Oauth2Service(
                new Google.Apis.Services.BaseClientService.Initializer());
            Oauth2Service.TokeninfoRequest request = service.Tokeninfo();
            request.AccessToken = accessToken;

            Tokeninfo info = request.Execute();
            Console.Write(@"Scope: " + info.Scope + "n");
            Console.WriteLine(@"Expires: " + info.ExpiresIn);
            Console.ReadLine();
        }

To make the API call, I’m just getting a service object for OAuth 2, constructing the request, adding the token, and finally executing the request.

Demo of Authorization: Get Google+ Profile information

In this demo, the user is authorized and then their profile information is retrieved and displayed.

First, as before, we’ll enable the required Google API client package, Google.Apis.Plus.v1. This will install additional client library dependencies.

The following is the full source of the main function:

        // These come from the APIs console:
        //   https://code.google.com/apis/console
        public static ClientSecrets secrets = new ClientSecrets()
        {
            ClientId = "YOUR_CLIENT_ID",
            ClientSecret = "YOUR_CLIENT_SECRET"
        };


        static void Main(string[] args)
        {
            Console.WriteLine(@"Starting authorization...");

            UserCredential credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                secrets,
                new[] { PlusService.Scope.PlusLogin },
                "me",
                CancellationToken.None).Result;

            // Create the service.
            var plusService = new PlusService(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
                ApplicationName = "Console Google+ Demo",
            });

            Person me = plusService.People.Get("me").Execute();

            Console.Write(@"Authorized user: " + me.DisplayName + "n");
            Console.Write(@"Press enter to exit.");
            Console.Read();
        }

You construct your credentials object with parameters from the Developer API console, authorize the user to get your credential, create your service object from the credential, and then can make your API calls with the service object.

Closing thoughts

Authorizing the user from the console is pretty easy. Note that doing so with the web browser is necessary because the user must input their credentials on the Google OAuth server.

More information can be found at: