How to authorize Google anlaytics data api with OAuth2

Question

I am trying to connect to the new Google Analytics Data api using C# to request data from the new google analytics GA4. The only sample i can find is Quickstart client libraries .net This does work but it uses a service account. The cloud .net client library google-cloud-dotnet only has examples for using a service account.

When i try to pass it desktop app credentials for using Oauth" authorization i get

Error creating credential from JSON. Unrecognized credential type.

using System;
using System.Threading;
using System.Threading.Tasks;
using Google.Analytics.Data.V1Beta;

namespace GoogleAnalyticsExamplesData
{
    class Program
    {
        private const string PropertyId = "250796939";
        private const string PathToCreds = @"C:\dev\ServiceAccountCred.json";

        static async Task Main(string[] args)
        {
            Console.WriteLine("Hello World!");

            // Check whether the environment variable exists.
            var environmentVariable = Environment.GetEnvironmentVariable("GOOGLE_APPLICATION_CREDENTIALS");
            // If necessary, create it.
            if (environmentVariable == null)
                Environment.SetEnvironmentVariable("GOOGLE_APPLICATION_CREDENTIALS", PathToCreds);

            await SampleRunReport(PropertyId);
        }
        
        static async Task SampleRunReport(string propertyId = "YOUR-GA4-PROPERTY-ID")
        {
            // Using a default constructor instructs the client to use the credentials
            // specified in GOOGLE_APPLICATION_CREDENTIALS environment variable.
            var client = await BetaAnalyticsDataClient.CreateAsync(CancellationToken.None);

            var request = new RunReportRequest
            {
                Property = "properties/" + PropertyId,
                Dimensions = {new Dimension {Name = "date"},},
                Metrics = {new Metric {Name = "totalUsers"}, new Metric {Name = "newUsers"}},
                DateRanges = {new DateRange {StartDate = "2021-04-01", EndDate = "today"},},
            };

            var response = await client.RunReportAsync(request);


            Console.WriteLine("Report result:");

            foreach (var row in response.Rows)
            {
                Console.WriteLine(
                    $"{row.DimensionValues[0].Value}, {row.MetricValues[0].Value}, {row.MetricValues[1].Value}");
            }
        }
    }
}

Links to Google.Analytics.Data.V1Beta Web client credentials, desktop credentials

Answer 1

After several hours of digging around i found that you can use ICredential using a builder. This works with a Desktop app credentials, for installed applications.

using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Google.Analytics.Data.V1Beta;
using Google.Apis.Auth.OAuth2;

using Google.Apis.Util.Store;

namespace GoogleAnalyticsExamplesData
{
    class Program
    {
        private const string PropertyId = "250796939";
        private const string PathToCreds = @"C:\dev\credentials.json";

        static async Task Main(string[] args)
        {
            Console.WriteLine("Hello World!");   
          

            await SampleRunReport(PropertyId);
        }

        static async Task SampleRunReport(string propertyId = "YOUR-GA4-PROPERTY-ID")
        {
            // Using a default constructor instructs the client to use the credentials
            // specified in GOOGLE_APPLICATION_CREDENTIALS environment variable.
            //var client = await BetaAnalyticsDataClient.CreateAsync(CancellationToken.None);

            BetaAnalyticsDataClient client ;
            await using (var stream = new FileStream(PathToCreds, FileMode.Open, FileAccess.Read))
            {
                // Requesting Authentication or loading previously stored authentication for userName
                var credential = GoogleWebAuthorizationBroker.AuthorizeAsync(GoogleClientSecrets.Load(stream).Secrets,
                    new[] { "https://www.googleapis.com/auth/analytics.readonly"},
                    "userName",
                    CancellationToken.None,
                    new FileDataStore("credPath", true)).Result;
                
                client = await new BetaAnalyticsDataClientBuilder
                {
                    TokenAccessMethod = credential.GetAccessTokenForRequestAsync
                }.BuildAsync();
            }

            var request = new RunReportRequest
            {
                Property = "properties/" + PropertyId,
                Dimensions = {new Dimension {Name = "date"},},
                Metrics = {new Metric {Name = "totalUsers"}, new Metric {Name = "newUsers"}},
                DateRanges = {new DateRange {StartDate = "2021-04-01", EndDate = "today"},},
            };

            var response = await client.RunReportAsync(request);


            Console.WriteLine("Report result:");

            foreach (var row in response.Rows)
            {
                Console.WriteLine(
                    $"{row.DimensionValues[0].Value}, {row.MetricValues[0].Value}, {row.MetricValues[1].Value}");
            }
        }
    }
}