List users in .NET apps using Microsoft Graph

In this article, you extend the application you created in Build .NET apps with Microsoft Graph and app-only authentication with Microsoft Graph user APIs. You use Microsoft Graph to list users in your organization.

1. Open ./GraphHelper.cs and add the following function to the GraphHelper class.

   public static Task<UserCollectionResponse?> GetUsersAsync()
   {
       // Ensure client isn't null
       _ = _appClient ??
           throw new System.NullReferenceException("Graph has not been initialized for app-only auth");
   
       return _appClient.Users.GetAsync((config) =>
       {
           // Only request specific properties
           config.QueryParameters.Select = new[] { "displayName", "id", "mail" };
           // Get at most 25 results
           config.QueryParameters.Top = 25;
           // Sort by display name
           config.QueryParameters.Orderby = new[] { "displayName" };
       });
   }
   

2. Replace the empty ListUsersAsync function in Program.cs with the following.

   async Task ListUsersAsync()
   {
       try
       {
           var userPage = await GraphHelper.GetUsersAsync();
   
           if (userPage?.Value == null)
           {
               Console.WriteLine("No results returned.");
               return;
           }
   
           // Output each users's details
           foreach (var user in userPage.Value)
           {
               Console.WriteLine($"User: {user.DisplayName ?? "NO NAME"}");
               Console.WriteLine($"  ID: {user.Id}");
               Console.WriteLine($"  Email: {user.Mail ?? "NO EMAIL"}");
           }
   
           // If NextPageRequest is not null, there are more users
           // available on the server
           // Access the next page like:
           // var nextPageRequest = new UsersRequestBuilder(userPage.OdataNextLink, _appClient.RequestAdapter);
           // var nextPage = await nextPageRequest.GetAsync();
           var moreAvailable = !string.IsNullOrEmpty(userPage.OdataNextLink);
   
           Console.WriteLine($"\nMore users available? {moreAvailable}");
       }
       catch (Exception ex)
       {
           Console.WriteLine($"Error getting users: {ex.Message}");
       }
   }
   

3. Run the app and choose option 2 to list users.

   Please choose one of the following options:
   0. Exit
   1. Display access token
   2. List users
   3. Make a Graph call
   2
   User: Adele Vance
     ID: 05fb57bf-2653-4396-846d-2f210a91d9cf
     Email: AdeleV@contoso.com
   User: Alex Wilber
     ID: a36fe267-a437-4d24-b39e-7344774d606c
     Email: AlexW@contoso.com
   User: Allan Deyoung
     ID: 54cebbaa-2c56-47ec-b878-c8ff309746b0
     Email: AllanD@contoso.com
   User: Bianca Pisani
     ID: 9a7dcbd0-72f0-48a9-a9fa-03cd46641d49
     Email: NO EMAIL
   User: Brian Johnson (TAILSPIN)
     ID: a8989e40-be57-4c2e-bf0b-7cdc471e9cc4
     Email: BrianJ@contoso.com
   
   ...
   
   More users available? True
   

Code explained

Consider the code in the GetUsersAsync function.

• It gets a collection of users
• It uses Select to request specific properties
• It uses Top to limit the number of users returned
• It uses OrderBy to sort the response

Next step