Simplify APIs

Pre-empt changes coming in a future preview, as it reduces the amount of code in the endpoints and gets rid of the need to cast to IResult for resolving ambiguity.

Author: martincostello

src/TodoApp/ApiModule.cs

@@ -3,7 +3,6 @@
 
 using System.Security.Claims;
 using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Routing;
 using TodoApp.Models;
@@ -19,10 +18,8 @@ public static IEndpointRouteBuilder MapApiRoutes(this IEndpointRouteBuilder buil
             builder.MapGet("/api/items", async (
                 ITodoService service,
                 ClaimsPrincipal user,
-                CancellationToken cancellationToken) =>
-            {
-                return await service.GetListAsync(user.GetUserId(), cancellationToken);
-            }).RequireAuthorization();
+                CancellationToken cancellationToken) => await service.GetListAsync(user.GetUserId(), cancellationToken))
+                .RequireAuthorization();
 
             // Get a specific Todo item
             builder.MapGet("/api/items/{id}", async (
@@ -32,13 +29,7 @@ public static IEndpointRouteBuilder MapApiRoutes(this IEndpointRouteBuilder buil
                 CancellationToken cancellationToken) =>
             {
                 var model = await service.GetAsync(user.GetUserId(), id, cancellationToken);
-
-                if (model is null)
-                {
-                    return new NotFoundResult();
-                }
-
-                return new JsonResult(model) as IResult;
+                return model is null ? Results.NotFound() : Results.Json(model);
             }).RequireAuthorization();
 
             // Create a new Todo item
@@ -50,12 +41,12 @@ public static IEndpointRouteBuilder MapApiRoutes(this IEndpointRouteBuilder buil
             {
                 if (model is null || string.IsNullOrWhiteSpace(model.Text))
                 {
-                    return new BadRequestResult();
+                    return Results.BadRequest();
                 }
 
                 var id = await service.AddItemAsync(user.GetUserId(), model.Text, cancellationToken);
 
-                return new CreatedAtResult($"/api/items/{id}", new { id }) as IResult;
+                return Results.Created($"/api/items/{id}", new { id });
             }).RequireAuthorization();
 
             // Mark a Todo item as completed
@@ -67,14 +58,12 @@ public static IEndpointRouteBuilder MapApiRoutes(this IEndpointRouteBuilder buil
             {
                 var wasCompleted = await service.CompleteItemAsync(user.GetUserId(), id, cancellationToken);
 
-                var statusCode = wasCompleted switch
+                return wasCompleted switch
                 {
-                    true => StatusCodes.Status204NoContent,
-                    false => StatusCodes.Status400BadRequest,
-                    _ => StatusCodes.Status404NotFound,
+                    true => Results.NoContent(),
+                    false => Results.BadRequest(),
+                    _ => Results.NotFound(),
                 };
-
-                return new StatusCodeResult(statusCode);
             }).RequireAuthorization();
 
             // Delete a Todo item
@@ -85,36 +74,10 @@ public static IEndpointRouteBuilder MapApiRoutes(this IEndpointRouteBuilder buil
                 CancellationToken cancellationToken) =>
             {
                 var wasDeleted = await service.DeleteItemAsync(user.GetUserId(), id, cancellationToken);
-
-                return new StatusCodeResult(wasDeleted ? StatusCodes.Status204NoContent : StatusCodes.Status404NotFound);
+                return wasDeleted ? Results.NoContent() : Results.NotFound();
             }).RequireAuthorization();
 
             return builder;
         }
-
-        // HACK Custom result types until CreatedAtResult/ObjectResult implements IResult.
-        // See https://github.com/dotnet/aspnetcore/issues/32565.
-
-        private sealed class CreatedAtResult : IResult
-        {
-            private readonly string _location;
-            private readonly object? _value;
-
-            internal CreatedAtResult(string location, object? value)
-            {
-                _location = location;
-                _value = value;
-            }
-
-            public async Task ExecuteAsync(HttpContext httpContext)
-            {
-                var response = httpContext.Response;
-
-                response.Headers.Location = _location;
-                response.StatusCode = StatusCodes.Status201Created;
-
-                await response.WriteAsJsonAsync(_value, httpContext.RequestAborted);
-            }
-        }
     }
 }

src/TodoApp/AuthenticationModule.cs

@@ -6,7 +6,6 @@
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Authentication.Cookies;
 using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -68,23 +67,19 @@ public static string GetUserName(this ClaimsPrincipal user)
 
         public static IEndpointRouteBuilder MapAuthenticationRoutes(this IEndpointRouteBuilder builder)
         {
-            // TODO Remove cast once supported by C# 10
-            builder.MapGet(DeniedPath, (Action<HttpContext>)(context => context.Response.Redirect(RootPath + "?denied=true")));
-            builder.MapGet(SignOutPath, (Action<HttpContext>)(context => context.Response.Redirect(RootPath)));
+            builder.MapGet(DeniedPath, () => Results.Redirect(RootPath + "?denied=true"));
+            builder.MapGet(SignOutPath, () => Results.Redirect(RootPath));
 
-            builder.MapPost(SignInPath, async context =>
-            {
-                await context.ChallengeAsync(
-                    GitHubAuthenticationDefaults.AuthenticationScheme,
-                    new AuthenticationProperties { RedirectUri = RootPath });
-            });
+            builder.MapPost(SignInPath, () =>
+                Results.Challenge(
+                    new AuthenticationProperties { RedirectUri = RootPath },
+                    GitHubAuthenticationDefaults.AuthenticationScheme));
 
-            builder.MapPost(SignOutPath, async context =>
-            {
-                await context.SignOutAsync(
-                    CookieAuthenticationDefaults.AuthenticationScheme,
-                    new AuthenticationProperties { RedirectUri = RootPath });
-            }).RequireAuthorization();
+            builder.MapPost(SignOutPath, () =>
+                Results.SignOut(
+                    new AuthenticationProperties { RedirectUri = RootPath },
+                    CookieAuthenticationDefaults.AuthenticationScheme))
+                .RequireAuthorization();
 
             return builder;
         }

src/TodoApp/Results.cs

@@ -0,0 +1,68 @@
+// Copyright (c) Martin Costello, 2021. All rights reserved.
+// Licensed under the Apache 2.0 license. See the LICENSE file in the project root for full license information.
+
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+
+namespace TodoApp
+{
+    // Will be redundant when changes are available in a later preview.
+    // See https://github.com/dotnet/aspnetcore/pull/33843.
+
+    internal sealed class Results
+    {
+        public static IResult BadRequest()
+            => new BadRequestResult();
+
+        public static IResult Challenge(AuthenticationProperties properties, params string[] authenticationSchemes)
+            => new ChallengeResult(authenticationSchemes, properties);
+
+        public static IResult Created(string url, object? value)
+            => new CreatedAtResult(url, value);
+
+        public static IResult Json(object? data)
+            => new JsonResult(data);
+
+        public static IResult NoContent()
+            => new NoContentResult();
+
+        public static IResult NotFound()
+            => new NotFoundResult();
+
+        public static IResult Redirect(string url)
+            => new RedirectResult(url);
+
+        public static IResult SignOut(AuthenticationProperties properties, params string[] authenticationSchemes)
+            => new SignOutResult(authenticationSchemes, properties);
+
+        public static IResult StatusCode(int statusCode)
+            => new StatusCodeResult(statusCode);
+
+        // HACK Custom result types until CreatedAtResult/ObjectResult implements IResult.
+        // See https://github.com/dotnet/aspnetcore/issues/32565
+        // and https://github.com/dotnet/aspnetcore/pull/33843.
+
+        private sealed class CreatedAtResult : IResult
+        {
+            private readonly string _location;
+            private readonly object? _value;
+
+            internal CreatedAtResult(string location, object? value)
+            {
+                _location = location;
+                _value = value;
+            }
+
+            public async Task ExecuteAsync(HttpContext httpContext)
+            {
+                var response = httpContext.Response;
+
+                response.Headers.Location = _location;
+                response.StatusCode = StatusCodes.Status201Created;
+
+                await response.WriteAsJsonAsync(_value, httpContext.RequestAborted);
+            }
+        }
+    }
+}