Google Analytics is a website statistics service offered by the internet giant Google. With the basic service being free of charge, it is definitely the most popular tool that the vast majority of webmasters rely on. It helps to gather a wide range of statistics about the visitors, social networks, search engines, or even Pay-Per-Click (PPC) networks and advertising.
All these statistics are comfortably accessible using the web interface, so webmasters can easily keep an eye on them. But what if you just need to display the statistics in your own website or desktop application? In this case, the Google Analytics API (currently in version V3) is available for fetching any kind of statistics you can think of.
Please note that discussing the entire API would be out of the scope of this article. I will focus solely on fetching some data (statistics) and displaying it in the form of a chart in a Windows Forms application.

Google Analytics Reporting API

The reporting API is a simple yet powerful Application Programming Interface (API) that allows developers to retrieve the Google Analytics data gathered by Google. To retrieve the statistics, some must be gathered first. Therefore, there is one important prerequisite to use the API. You need to have a Google account and a website with the tracking code. I assume you already know how to generate the JavaScript tracking code and insert it into your website.
Google Analytics tracking code
Image 1: Google Analytics tracking code
Enabling the API Access
There are two options for fetching the data. The first option is the Simple API access that doesn't allow accessing any private user data, so it is not sufficient for our purpose. The second approach is the Authorized API access (OAuth 2.0) which allows us to access private user data, so we will use it.
In order to rely on OAuth 2.0, our application must be authenticated and the user must grant access to it. To do so, several steps must be taken.
First, we need to log on to the Google Developers Console with our Google account and create a new project.
Creating Google Developers project
Image 2: Creating Google Developers' project
We will name the project “Csharpacess” and leave the auto-generated Project ID as it is.
new project
Image 3: Creating a new project
Once the project is created, we are being redirected to its dashboard. Now, we need to enable the analytics API and create new access credentials.
created project dashboard
Image 4: Newly created project's dashboard
After clicking on “APIs” in the left menu bar, we are being taken to the APIs list. Now we scroll down to find the Analytics API and turn it on by clicking on the “OFF” button.
Enabling the Analytics API
Image 5: Enabling the Analytics API
Once turned on, we will create new credentials by clicking the “Credentials” in the menu on the left. As said above, we need to rely on OAuth if we want to access private user's data, so we will create a new ID by clicking on the “Create new Client ID” button.
Creating new access credentials
Image 6: Creating new access credentials
Now, we need to choose between three types of Client IDs. Because we will use it in our desktop application, we will choose the “Service account” option.
Creating the Service Account client ID
Image 7: Creating the Service Account client ID
Once created, the browser will prompt us to save the private key to our computer. We will need the certificate for authentication, so we will save it to our computer for later use. Also, we will rename it to “Csharpaccess.p12” for easier use. Please pay attention to the auto-generated private key's password “notasecret”. We will need it in our C# application, so I encourage you to write it down or save it to some temporary file.
Downloading the certificate
Image 8: Downloading the certificate
After the download, we are being redirected back to the dashboard with the added Service account credentials. These are now accessible anytime we need to through the Google Developers Console. However, we will need these credentials later, so we will copy them to some temporary text file for faster access.
Created Service Account credentials
Image 9: Created Service Account credentials
From now on, we have successfully created an OAuth 2.0 access. The next step is to pair it with our website through Google Analytics.
Pairing with Google Analytics
 The Reporting API credentials we have just created can be used to access as many websites as we need to. All we need to do is add a new user for the desired website(s) using the Google Analytics User Management. Like an email address, we need to use the email address that was generated for the OAuth 2.0 authentication in the previous step.
Therefore, we will use “568017249870-9pqlki56dvp3bn64hb2pnvlnais8ndes@developer.gserviceaccount.com” in the email TextBox while leaving the default Read and Analyze permission since that is all we need in this case.
Adding new Google Analytics user
Image 10: Adding new Google Analytics user
From now, everything is set up, so we can start Visual Studio and create our desktop application.
Creating Simple Windows Forms Application
I assume you already have some C# basics, so I will not talk about creating the form or the buttons. Instead, I will focus solely on retrieving and displaying the gathered data using the OAuth 2.0 authentication we have just created.
Note: We must ensure that our Visual Studio project is set to target the .NET Framework 4.0 or .NET Framework 4.5.
Adding necessary references
We start by adding some required libraries' references. To install Google.Apis.Analytics.v3 Client Library, we use the popular NuGet Package Manager Console (Tools -> NuGet Package Manager). Open the console and use the following command to install the library:
Install-Package Google.Apis.Analytics.v3
NuGet Console
Image 11: Installing Google.Apis.Analytics.v3 library with NuGet Console
After the installation process is over, we can open the project's references to verify that the additional libraries were added.
New references successfully added
Image 12: New references successfully added
Initializing and authenticating the service
We start by declaring some variables we will need.
  1. private string keyFilePath = @"Csharpaccess.p12";
  2. private string serviceAccountEmail = "568017249870-9pqlki56dvp3bn64hb2pnvlnais8ndes@developer.gserviceaccount.com";
  3. private string keyPassword = "notasecret";
  4. private string websiteCode = "86391935";
  5. private AnalyticsService service = null;
These are as follows:
Authenticating the service
 For authenticating purposes, we create a private method called Authenticate.
First, we start by creating the X509Certificate2 object. In order to work with this type of object, we need to import the corresponding namespace with the "using" directive. The object's constructor takes three arguments – the physical file path of the certificate, the password to access it, and a storage flags that handles the private key import. We have already declared the first two arguments in the previous step and for the third one, we will choose Exportable from the X509KeyStorageFlags enumeration.
Don't forget: the first parameter is the physical path and name of the certificate, so do not forget to copy the downloaded certificate to the debug folder of the project.
  1. using System.Security.Cryptography.X509Certificates;
  3. //loading the Key file
  4. var certificate = new X509Certificate2(keyFilePath, keyPassword, X509KeyStorageFlags.Exportable);
Next, we define the access scopes for the service in the form of a string array. There are several scopes to choose from, but the AnalyticsReadonly is the only one we care about. However, for the purpose of this tutorial, we will add the other ones as well.
  1. var scopes =
  2. new string[] {
  3. AnalyticsService.Scope.Analytics, // view and manage your analytics data
  4. AnalyticsService.Scope.AnalyticsEdit, // edit management actives
  5. AnalyticsService.Scope.AnalyticsManageUsers, // manage users
  6. AnalyticsService.Scope.AnalyticsReadonly}; // View analytics data
Now, we will create a new ServiceAccountCredential for the certificate. After adding Google.Apis.Auth.OAuth2 namespace with the "using" directive, we use some variables that are already declared to create and initialize the object.
  1. using Google.Apis.Auth.OAuth2;
  3. var credential = new ServiceAccountCredential(new ServiceAccountCredential.Initializer(serviceAccountEmail)
  4. {
  5. Scopes = scopes
  6. }.FromCertificate(certificate));
Finally, we create the service itself and authenticate to it. Note that we need to add the Google.Apis.Services namespace first.
  1. using Google.Apis.Services;
  3. service = new AnalyticsService(new BaseClientService.Initializer()
  4. {
  5. HttpClientInitializer = credential
  6. });
Querying data
For querying the Analytics data, we use the service's Get method that populates the GetRequest object. This method takes the four parameters, the website code with the "ga:" prefix, the start date, the end date, and the metrics. The first three speak for themselves. When it comes to metrics, this is basically the type of data we want to query.
For further reference, I advise you to visit the Dimensions & Metrics Reference guide where you can learn about all the kinds of metrics and common data queries. For our purposes, I will use the "sessions" metric because it represents the visits we are interested in. For the date range, we will use the prior 15 days and we need to cast it to a proper string format.
We also need to add some statistical dimensions, otherwise, only aggregate values for the requested date range will be returned. Because we want to query the number of daily visits and display it in a chart, we add year, month, and day dimensions. Finally, we execute the request to get the data.
  1. DataResource.GaResource.GetRequest request = service.Data.Ga.Get(
  2. "ga:" + websiteCode,
  3. DateTime.Today.AddDays(-15).ToString("yyyy-MM-dd"),
  4. DateTime.Today.ToString("yyyy-MM-dd"),
  5. "ga:sessions");
  6. request.Dimensions = "ga:year,ga:month,ga:day";
  7. var data = request.Execute();
Populating the visits list
For easier data manipulation and chart databinding, we have created a dummy ChartRecord class and declared a list of records in the class's scope.
  1. private List<ChartRecord> visitsData = new List<ChartRecord>();
  3. class ChartRecord
  4. {
  5. public ChartRecord(string date, int visits)
  6. {
  7. _date = date;
  8. _visits = visits;
  9. }
  10. private string _date;
  11. public string Date
  12. {
  13. get { return _date; }
  14. set { _date = value; }
  15. }
  16. private int _visits;
  17. public int Visits
  18. {
  19. get { return _visits; }
  20. set { _visits = value; }
  21. }
  22. }
Now, we can easily iterate the requested data and fill in the ChartRecord list.
  1. foreach (var row in data.Rows)
  2. {
  3. visitsData.Add(new ChartRecord(new DateTime(int.Parse(row[0]), int.Parse(row[1]), int.Parse(row[2])).ToString("MM-dd-yyyy"), int.Parse(row[3])));
  4. }
Visually displaying the data
 To visually display the requested analytics data, we will use the out-of-the-box Windows Forms chart control and databind the list to it.
  1. analyticsChart.Series[0].XValueMember = "Date";
  2. analyticsChart.Series[0].YValueMembers = "Visits";
  3. analyticsChart.DataSource = visitsData;
  4. analyticsChart.DataBind();
fetched statistics in a form of chart
Image 14: fetched statistics in a form of a chart
Putting it altogether
 There is a demo application attached for download. I left all the accesses enabled, so you can experiment with the API and all the metrics/dimensions available.

Conclusion

Even though Google Analytics's web interface is sufficient for most webmasters, there are specific occasions when you need to display the data locally in your own application. In this case, we use the Reporting API that offers a wide range of functionality and its usage is straightforward and well documented.