Read Files From Google Photos Using Google Photos API, REST And C#.NET

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I've been working on a project last year to read and download images from Google Photos using the recent Google Photos API and C# as the programming language. During research, there was an existing .NET API called Picasa Web Albums API but has been deprecated and the docs suggested to migrate applications to the recent one. The examples in the current documentation provided are PHP, Java and REST API in which the example is written in Node.js. Since the requirement is to write a scheduled task or windows service in C#.NET, I decided to refresh my skills on sending requests to REST services using WebClient or HTTPWebRequest classes.

To access media items, read or even download files using Google Photos API, you need to enable the Google Photos Library API, create a Google Project and setup OAuth 2.0 credentials correctly. See Get started with REST documentation for a step by step guide on how to accomplish them.

Once the setup stage has been completed, you need to download the JSON file that contains your credentials such as Client Secret ID and Client Secret and then add them to your Visual Studio project. In the screenshot below, I attached the JSON file and renamed it to 'credentials'. Set the Copy to output directory of that file to Copy Always.

Next is to create the model classes that will convert the JSON result into a .NET object.

public class clsResponseRootObject
   {
      public List<MediaItem> mediaItems { get; set; }
      public string nextPageToken { get; set; }
   }

   public class MediaItem
   {
      public string id { get; set; }
      public string productUrl { get; set; }
      public string baseUrl { get; set; }
      public string mimeType { get; set; }
      public MediaMetadata mediaMetadata { get; set; }
      public string filename { get; set; }
   }

   public class MediaMetadata
   {
      public DateTime creationTime { get; set; }
      public string width { get; set; }
      public string height { get; set; }
      public Photo photo { get; set; }
   }

   public class Photo
   {
      public string cameraMake { get; set; }
      public string cameraModel { get; set; }
      public double focalLength { get; set; }
      public double apertureFNumber { get; set; }
      public int isoEquivalent { get; set; }
   }

To proceed with reading the files from Google Photos Library, install the Google.Apis.Auth package in your project via NuGet. The entire code to read the files is shown below.

using Google.Apis.Auth.OAuth2;
using Google.Apis.Util.Store;
using Newtonsoft.Json;
using System;
using System.IO;
using System.Net;
using System.Text;
using System.Threading;

namespace GooglePhotosAPISimpleDemo
{
   class Program
   {
      static void Main(string[] args)
      {
         string credPath = @"D:\StorePath\";
         clsResponseRootObject responseObject = new clsResponseRootObject();
         UserCredential credential;
         string[] scopes = {
            "https://www.googleapis.com/auth/photoslibrary.sharing",
            "https://www.googleapis.com/auth/photoslibrary.readonly"
         };
         string UserName = "your_googlemail_account";
         string ClientID = "your_client_id";
         string ClientSecret = "your_client_secret";

         using (var stream = new FileStream("credentials.json", FileMode.Open, FileAccess.Read))
         {
            credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                GoogleClientSecrets.Load(stream).Secrets,
                scopes,
                UserName,
                CancellationToken.None,
                new FileDataStore(credPath, true)).Result;
         }

         try
         {
            HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create("https://photoslibrary.googleapis.com/v1/mediaItems");
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Headers.Add("client_id", ClientID);
            httpWebRequest.Headers.Add("client_secret", ClientSecret);
            httpWebRequest.Headers.Add("Authorization:" + credential.Token.TokenType + " " + credential.Token.AccessToken);
            httpWebRequest.Method = "GET";

            HttpWebResponse response = httpWebRequest.GetResponse() as HttpWebResponse;
            using (Stream responseStream = response.GetResponseStream())
            {
               StreamReader reader = new StreamReader(responseStream, Encoding.UTF8);

               responseObject = JsonConvert.DeserializeObject<clsResponseRootObject>(reader.ReadToEnd());

               if (responseObject != null)
               {
                  if (responseObject.mediaItems != null && responseObject.mediaItems.Count > 0)
                  {
                     Console.WriteLine("------------------------Retrieving media files--------------------------------");
                     foreach (var item in responseObject.mediaItems)
                     { 
                        Console.WriteLine(string.Format("ID:{0}, Filename:{1}, MimeType:{2}", item.id, item.filename, item.mimeType));
                     }
                  }
               }
            }
         }
         catch (Exception ex)
         {
            Console.WriteLine("Error occured: " + ex.Message);
         }

         Console.ReadLine();
      }
   }
}

If you run the application, an Internet Explorer Browser will show on your desktop and will ask you to enter your email address as confirmation.

Once you click Allow, the program will then display the files you uploaded in your Photos Library.