Analytics Reporting v4 with API key

Question

I need to integrate a very basic report from Google Analytics in the dashboard page of a CMS web application I\'m building with asp.net web forms (C#).

I remember I

Answer 1

API key is for accessing public data only which means you could only use it with the metadata api.

Google Analytics data is private data owned by a user. Since this is your own data that you are trying to access you should create a service account. Service accounts are preauthorized. Go to Google developer console and create service account credentials. Then take the service account email address and add it as a user at the ACCOUNT level in the admin section of the google analytics website. It MUST be the ACCOUNT level. You have now authorized the service account to access the data of that account.

Service account Auth

// Copyright 2017 DAIMTO :  www.daimto.com
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
// an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by DAIMTO-Google-apis-Sample-generator 1.0.0
//     Template File Name:  ServiceAccount.tt
//     Build date: 01/02/2017 22:31:50
//     C# generater version: 1.0.0
//     
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

// About 
// 
// Unoffical sample for the AnalyticsReporting v4 API for C#. 
// This sample is designed to be used with the Google .Net client library. (https://github.com/google/google-api-dotnet-client)
// 
// API Description: Accesses Analytics report data.
// API Documentation Link https://developers.google.com/analytics/devguides/reporting/core/v4/
//
// Discovery Doc  https://www.googleapis.com/discovery/v1/apis/AnalyticsReporting/v4/rest
//
//------------------------------------------------------------------------------
// Installation
//
// This sample code uses the Google .Net client library 
//
// NuGet package:
//
// Location: https://www.nuget.org/packages/Google.Apis.AnalyticsReporting.v4/ 
// Install Command: PM>  Install-Package Google.Apis.AnalyticsReporting.v4
//
//------------------------------------------------------------------------------  
using Google.Apis.AnalyticsReporting.v4
using Google.Apis.Auth.OAuth2;
using Google.Apis.Services;
using System;
using System.IO;
using System.Security.Cryptography.X509Certificates;

namespace GoogleSamplecSharpSample.AnalyticsReportingv4.Auth
{

    public class static ServiceAccountExample
    {

        /// <summary>
        /// Authenticating to Google using a Service account
        /// Documentation: https://developers.google.com/accounts/docs/OAuth2#serviceaccount
        /// </summary>
        /// <param name="serviceAccountEmail">From Google Developer console https://console.developers.google.com</param>
        /// <param name="serviceAccountCredentialFilePath">Location of the .p12 or Json Service account key file downloaded from Google Developer console https://console.developers.google.com</param>
        /// <returns>AnalyticsService used to make requests against the Analytics API</returns>
        public static AnalyticsReportingService AuthenticateServiceAccount(string serviceAccountEmail, string serviceAccountCredentialFilePath)
        {
            try
            {
                if (string.IsNullOrEmpty(serviceAccountCredentialFilePath))
                    throw new Exception("Path to the service account credentials file is required.");
                if (!File.Exists(serviceAccountCredentialFilePath))
                    throw new Exception("The service account credentials file does not exist at: " + serviceAccountCredentialFilePath);
                if (string.IsNullOrEmpty(serviceAccountEmail))
                    throw new Exception("ServiceAccountEmail is required.");

                // These are the scopes of permissions you need. It is best to request only what you need and not all of them
                string[] scopes = new string[] { AnalyticsReportingService.Scope.Analytics };             // View your Google Analytics data

                // For Json file
                if (Path.GetExtension(serviceAccountCredentialFilePath).ToLower() == ".json")
                {
                    GoogleCredential credential;
                    using (var stream = new FileStream(serviceAccountCredentialFilePath, FileMode.Open, FileAccess.Read))
                    {
                        credential = GoogleCredential.FromStream(stream)
                             .CreateScoped(scopes);
                    }

                    // Create the  Analytics service.
                    return new AnalyticsReportingService(new BaseClientService.Initializer()
                    {
                        HttpClientInitializer = credential,
                        ApplicationName = "AnalyticsReporting Service account Authentication Sample",
                    });
                }
                else if (Path.GetExtension(serviceAccountCredentialFilePath).ToLower() == ".p12")
                {   // If its a P12 file

                    var certificate = new X509Certificate2(serviceAccountCredentialFilePath, "notasecret", X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.Exportable);
                    var credential = new ServiceAccountCredential(new ServiceAccountCredential.Initializer(serviceAccountEmail)
                    {
                        Scopes = scopes
                    }.FromCertificate(certificate));

                    // Create the  AnalyticsReporting service.
                    return new AnalyticsReportingService(new BaseClientService.Initializer()
                    {
                        HttpClientInitializer = credential,
                        ApplicationName = "AnalyticsReporting Authentication Sample",
                    });
                }
                else
                {
                    throw new Exception("Unsupported Service accounts credentials.");
                }

            }
            catch (Exception ex)
            {
                Console.WriteLine("Create service account AnalyticsReportingService failed" + ex.Message);
                throw new Exception("CreateServiceAccountAnalyticsReportingFailed", ex);
            }
        }
    }
}

Code ripped from my Google-api-Dotnet samples project for Reporting API

Once you have created your service you should be able to use the code on the samples page for C#

I have an old tutorial on Service accounts with V3. Google Analytics Authentication