Program.cs

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license.

using System;
using System.Collections.Generic;
using Microsoft.Identity.Client;
using Microsoft.Graph;
using Microsoft.Extensions.Configuration;
using Helpers;

namespace graphconsoleapp
{
  public class Program
  {
    private static GraphServiceClient? _graphClient;

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

      var config = LoadAppSettings();
      if (config == null)
      {
        Console.WriteLine("Invalid appsettings.json file.");
        return;
      }

      var client = GetAuthenticatedGraphClient(config);

      var graphRequest = client.Users
                          .Request()
                          .Select(u => new { u.DisplayName, u.Mail })
                          .Top(15)
                          // .OrderBy("DisplayName desc)
                          .Filter("startsWith(surname,'A') or startsWith(surname,'B') or startsWith(surname,'C')");

      var results = graphRequest.GetAsync().Result;
      foreach (var user in results)
      {
        Console.WriteLine(user.Id + ": " + user.DisplayName + " <" + user.Mail + ">");
      }

      Console.WriteLine("\nGraph Request:");
      Console.WriteLine(graphRequest.GetHttpRequestMessage().RequestUri);
    }

    private static IConfigurationRoot? LoadAppSettings()
    {
      try
      {
        var config = new ConfigurationBuilder()
                          .SetBasePath(System.IO.Directory.GetCurrentDirectory())
                          .AddJsonFile("appsettings.json", false, true)
                          .Build();

        if (string.IsNullOrEmpty(config["applicationId"]) ||
            string.IsNullOrEmpty(config["applicationSecret"]) ||
            string.IsNullOrEmpty(config["redirectUri"]) ||
            string.IsNullOrEmpty(config["tenantId"]))
        {
          return null;
        }

        return config;
      }
      catch (System.IO.FileNotFoundException)
      {
        return null;
      }
    }

    private static IAuthenticationProvider CreateAuthorizationProvider(IConfigurationRoot config)
    {
      var clientId = config["applicationId"];
      var clientSecret = config["applicationSecret"];
      var redirectUri = config["redirectUri"];
      var authority = $"https://login.microsoftonline.com/{config["tenantId"]}/v2.0";

      List<string> scopes = new List<string>();
      scopes.Add("https://graph.microsoft.com/.default");

      var cca = ConfidentialClientApplicationBuilder.Create(clientId)
                                              .WithAuthority(authority)
                                              .WithRedirectUri(redirectUri)
                                              .WithClientSecret(clientSecret)
                                              .Build();
      return new MsalAuthenticationProvider(cca, scopes.ToArray());
    }

    private static GraphServiceClient GetAuthenticatedGraphClient(IConfigurationRoot config)
    {
      var authenticationProvider = CreateAuthorizationProvider(config);
      _graphClient = new GraphServiceClient(authenticationProvider);
      return _graphClient;
    }
  }
}