Add PerRequestAuthProvider delegate handler with extension method.

Author: peombwa

src/Microsoft.Graph.Core/Extensions/BaseRequestExtensions.cs

@@ -12,6 +12,28 @@ namespace Microsoft.Graph
     /// </summary>
     public static class BaseRequestExtensions
     {
+        /// <summary>
+        /// Sets the default authentication provider to the default Authentication Middleware Handler for this request.
+        /// This only works with the default authentication handler.
+        /// If you use a custom authentication handler, you have to handle it's retreival in your implementation.
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="baseRequest">The <see cref="BaseRequest"/> for the request.</param>
+        /// <returns></returns>
+        internal static T WithDefaultAuthProvider<T>(this T baseRequest) where T : IBaseRequest
+        {
+            string authOptionKey = typeof(AuthOption).ToString();
+            if (baseRequest.MiddlewareOptions.ContainsKey(authOptionKey))
+            {
+                (baseRequest.MiddlewareOptions[authOptionKey] as AuthOption).AuthenticationProvider = baseRequest.Client.AuthenticationProvider;
+            }
+            else
+            {
+                baseRequest.MiddlewareOptions.Add(authOptionKey, new AuthOption { AuthenticationProvider = baseRequest.Client.AuthenticationProvider });
+            }
+            return baseRequest;
+        }
+
         /// <summary>
         /// Sets Microsoft Graph's scopes to the default Authentication Middleware Handler for this request in order to perform incremental conscent.
         /// This only works with the default authentication handler and default set of Microsoft graph authentication providers.
@@ -60,24 +82,27 @@ public static T WithForceRefresh<T>(this T baseRequest, bool forceRefresh) where
         }
 
         /// <summary>
-        /// Sets an authentication provider to the default Authentication Middleware Handler for this request.
+        /// Sets the PerRequestAuthProvider delegate handler to the default Authentication Middleware Handler to authenticate a single request.
+        /// The PerRequestAuthProvider delegate handler must be set to the GraphServiceClient instance before using this extension method otherwise, it defaults to the default authentication provider.
         /// This only works with the default authentication handler.
         /// If you use a custom authentication handler, you have to handle it's retreival in your implementation.
         /// </summary>
         /// <typeparam name="T"></typeparam>
         /// <param name="baseRequest">The <see cref="BaseRequest"/> for the request.</param>
-        /// <param name="authenticationProvider">A <see cref="IAuthenticationProvider"/></param>
         /// <returns></returns>
-        public static T WithAuthProvider<T>(this T baseRequest, IAuthenticationProvider authenticationProvider) where T : IBaseRequest
+        public static T WithPerRequestAuthProvider<T>(this T baseRequest) where T : IBaseRequest
         {
-            string authOptionKey = typeof(AuthOption).ToString();
-            if (baseRequest.MiddlewareOptions.ContainsKey(authOptionKey))
-            {
-                (baseRequest.MiddlewareOptions[authOptionKey] as AuthOption).AuthenticationProvider = authenticationProvider;
-            }
-            else
+            if (baseRequest.Client.PerRequestAuthProvider != null)
             {
-                baseRequest.MiddlewareOptions.Add(authOptionKey, new AuthOption { AuthenticationProvider = authenticationProvider });
+                string authOptionKey = typeof(AuthOption).ToString();
+                if (baseRequest.MiddlewareOptions.ContainsKey(authOptionKey))
+                {
+                    (baseRequest.MiddlewareOptions[authOptionKey] as AuthOption).AuthenticationProvider = baseRequest.Client.PerRequestAuthProvider();
+                }
+                else
+                {
+                    baseRequest.MiddlewareOptions.Add(authOptionKey, new AuthOption { AuthenticationProvider = baseRequest.Client.PerRequestAuthProvider() });
+                }
             }
             return baseRequest;
         }

src/Microsoft.Graph.Core/Requests/BaseClient.cs

@@ -4,7 +4,7 @@
 
 namespace Microsoft.Graph
 {
-    using System.Threading.Tasks;
+    using System;
 
     /// <summary>
     /// A default <see cref="IBaseClient"/> implementation.
@@ -60,5 +60,10 @@ public string BaseUrl
         /// Gets the <see cref="IHttpProvider"/> for sending HTTP requests.
         /// </summary>
         public IHttpProvider HttpProvider { get; private set; }
+
+        /// <summary>
+        /// Gets or Sets the <see cref="IAuthenticationProvider"/> for authenticating a single HTTP requests. 
+        /// </summary>
+        public Func<IAuthenticationProvider> PerRequestAuthProvider { get; set; }
     }
 }

src/Microsoft.Graph.Core/Requests/BaseRequest.cs

@@ -53,8 +53,9 @@ public BaseRequest(
                 }
             }
 
-            // Adds base clients authentication provider middleware options (Default auth provider)
-            this.WithAuthProvider(this.Client.AuthenticationProvider);
+            // Adds the default authentication provider for this request. 
+            // This can be changed can be changed by the user by calling WithPerRequestAuthProvider extension method.
+            this.WithDefaultAuthProvider();
         }
 
         /// <summary>

src/Microsoft.Graph.Core/Requests/GraphClientFactory.cs

@@ -77,10 +77,10 @@ internal static class GraphClientFactory
 
 
         /// <summary>
-        /// Creates a new <see cref="HttpClient"/> instance configured with the handlers provided and with the
-        /// provided <paramref name="innerHandler"/> as the innermost handler.
+        /// Creates a new <see cref="HttpClient"/> instance configured with the handlers provided.
         /// </summary>
-        /// <param name="innerHandler">The inner handler represents the destination of the HTTP message channel.</param>
+        /// <param name="version">The graph version to use.</param>
+        /// <param name="nationalCloud">The national cloud endpoint to use.</param>
         /// <param name="handlers">An ordered list of <see cref="DelegatingHandler"/> instances to be invoked as an
         /// <see cref="HttpRequestMessage"/> travels from the <see cref="HttpClient"/> to the network and an
         /// <see cref="HttpResponseMessage"/> travels from the network back to <see cref="HttpClient"/>.

src/Microsoft.Graph.Core/Requests/IBaseClient.cs

@@ -4,6 +4,8 @@
 
 namespace Microsoft.Graph
 {
+    using System;
+
     /// <summary>
     /// Interface for the base client.
     /// </summary>
@@ -23,5 +25,10 @@ public interface IBaseClient
         /// Gets the <see cref="IHttpProvider"/> for sending HTTP requests.
         /// </summary>
         IHttpProvider HttpProvider { get; }
+
+        /// <summary>
+        /// Gets or Sets the <see cref="IAuthenticationProvider"/> for authenticating a single HTTP requests. 
+        /// </summary>
+        Func<IAuthenticationProvider> PerRequestAuthProvider { get; set; }
     }
 }