I'm getting error that DelegateAuthenticationProvider and MeRequestBuilder are not found in the graphService client I use to read Microsoft 365 mail

Question

Since Microsoft has switched from basic auth to bearer auth as of 2023, I cannot perform mail reading operations. I am trying to read with GraphServiceClient, but I am getting the below mentioned errors,can you help?

*- CS0246-->The type or namespace name 'DelegateAuthenticationProvider' could not be found (are you missing a using directive or an assembly reference?)

• CS1061--> 'MeRequestBuilder' does not contain a definition for 'Request' and no accessible extension method 'Request' accepting a first argument of type 'MeRequestBuilder' could be found (are you missing a using directive or an assembly reference?)*

using Microsoft.Graph;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Web;
using System.Net.Http.Headers;
using Microsoft.Identity.Client;
namespace GraphTest.Helpers
{
    public class GraphHelper
    {
        public static async Task<CachedUser> GetUserDetailsAsync(string accessToken)
        {
            var graphClient = new GraphServiceClient(
                new DelegateAuthenticationProvider(
                    async (requestMessage) =>
                    {
                        requestMessage.Headers.Authorization =
                            new AuthenticationHeaderValue("Bearer", accessToken);
                    }));

            var user = await graphClient.Me.Request()
                .Select(u => new
                {
                    u.DisplayName,
                    u.Mail,
                    u.UserPrincipalName
                })
                .GetAsync();

            return new CachedUser
            {
                Avatar = string.Empty,
                DisplayName = user.DisplayName,
                Email = string.IsNullOrEmpty(user.Mail) ?
                    user.UserPrincipalName : user.Mail
            };  
        }  
    }  
}

Answer 1

The v5 SDK had a lot of changes, you can read about it here :

https://github.com/microsoftgraph/msgraph-sdk-dotnet/blob/dev/docs/upgrade-to-v5.md

Authentication

In place of the DelegateAuthenticationProvider, custom authentication flows can be done creating an implementation of IAccessTokenProvider, and using with the BaseBearerTokenAuthenticationProvider from the Kiota abstractions as follows

public class TokenProvider : IAccessTokenProvider
{
    public Task<string> GetAuthorizationTokenAsync(Uri uri, Dictionary<string, object> additionalAuthenticationContext = default,
        CancellationToken cancellationToken = default)
    {
        var token = "token";
        // get the token and return it in your own way
        return Task.FromResult(token);
    }

    public AllowedHostsValidator AllowedHostsValidator { get; }
}

Then create the GraphServiceClient as follows

var authenticationProvider = new BaseBearerTokenAuthenticationProvider(new TokenProvider());
var graphServiceClient = new GraphServiceClient(authenticationProvider);

Removal of Request() from the fluent API

In previous versions, of the SDK, calls involved the calling of Request() in the request API as follows

var user = await graphServiceClient
.Me
.Request()  // this is removed
.GetAsync();

A similar call in the V5 will have the Request() section removed to be called as below.

var user = await graphServiceClient
.Me
.GetAsync();