Merge pull request #168 from ServiceComposer/custom-status-code

Support custom HTTP status code

README.md

@@ -57,7 +57,7 @@ public class SampleHandler : ICompositionRequestsHandler
     }
 }
 ```
-<sup><a href='/src/Snippets.NetCore3x/SampleHandler/SampleHandler.cs#L9-L18' title='File snippet `net-core-3x-sample-handler` was extracted from'>snippet source</a> | <a href='#snippet-net-core-3x-sample-handler' title='Navigate to start of snippet `net-core-3x-sample-handler`'>anchor</a></sup>
+<sup><a href='/src/Snippets.NetCore3x/SampleHandler/SampleHandler.cs#L10-L19' title='File snippet `net-core-3x-sample-handler` was extracted from'>snippet source</a> | <a href='#snippet-net-core-3x-sample-handler' title='Navigate to start of snippet `net-core-3x-sample-handler`'>anchor</a></sup>
 <!-- endsnippet -->
 
 #### Authentication and Authorization
@@ -77,9 +77,33 @@ public class SampleHandlerWithAuthorization : ICompositionRequestsHandler
     }
 }
 ```
-<sup><a href='/src/Snippets.NetCore3x/SampleHandler/SampleHandler.cs#L20-L30' title='File snippet `net-core-3x-sample-handler-with-authorization` was extracted from'>snippet source</a> | <a href='#snippet-net-core-3x-sample-handler-with-authorization' title='Navigate to start of snippet `net-core-3x-sample-handler-with-authorization`'>anchor</a></sup>
+<sup><a href='/src/Snippets.NetCore3x/SampleHandler/SampleHandler.cs#L21-L31' title='File snippet `net-core-3x-sample-handler-with-authorization` was extracted from'>snippet source</a> | <a href='#snippet-net-core-3x-sample-handler-with-authorization' title='Navigate to start of snippet `net-core-3x-sample-handler-with-authorization`'>anchor</a></sup>
 <!-- endsnippet -->
 
+#### Custom HTTP status codes in ASP.NET Core 3.x
+
+The response status code can be set in requests handlers and it'll be honored by the composition pipeline. To set a custom response status code the following snippet can be used:
+
+<!-- snippet: net-core-3x-sample-handler-with-custom-status-code -->
+<a id='snippet-net-core-3x-sample-handler-with-custom-status-code'></a>
+```cs
+public class SampleHandlerWithCustomStatusCode : ICompositionRequestsHandler
+{
+    [HttpGet("/sample/{id}")]
+    public Task Handle(HttpRequest request)
+    {
+        var response = request.HttpContext.Response;
+        response.StatusCode = (int)HttpStatusCode.Forbidden;
+
+        return Task.CompletedTask;
+    }
+}
+```
+<sup><a href='/src/Snippets.NetCore3x/SampleHandler/SampleHandler.cs#L33-L45' title='File snippet `net-core-3x-sample-handler-with-custom-status-code` was extracted from'>snippet source</a> | <a href='#snippet-net-core-3x-sample-handler-with-custom-status-code' title='Navigate to start of snippet `net-core-3x-sample-handler-with-custom-status-code`'>anchor</a></sup>
+<!-- endsnippet -->
+
+NOTE: Requests handlers are executed in parallel in a non-deterministic way, setting the response code in more than one handler can have unpredictable effects.
+
 ### ASP.NET Core 2.x
 
 Create a new .NET Core console project and add a reference to the following Nuget packages:
@@ -124,6 +148,34 @@ More details on how to implement `IHandleRequests` and `ISubscribeToCompositionE
 * [ViewModel Composition: show me the code!](https://milestone.topics.it/view-model-composition/2019/03/06/viewmodel-composition-show-me-the-code.html)
 * [The ViewModels Lists Composition Dance](https://milestone.topics.it/view-model-composition/2019/03/21/the-viewmodels-lists-composition-dance.html)
 
+#### Custom HTTP status codes in ASP.NET Core 2.x
+
+The response status code can be set in requests handlers and it'll be honored by the composition pipeline. To set a custom response status code the following snippet can be used:
+
+<!-- snippet: net-core-2x-sample-handler-with-custom-status-code -->
+<a id='snippet-net-core-2x-sample-handler-with-custom-status-code'></a>
+```cs
+public class SampleHandlerWithCustomStatusCode : IHandleRequests
+{
+    public bool Matches(RouteData routeData, string httpVerb, HttpRequest request)
+    {
+        return true;
+    }
+
+    public Task Handle(string requestId, dynamic vm, RouteData routeData, HttpRequest request)
+    {
+        var response = request.HttpContext.Response;
+        response.StatusCode = (int)HttpStatusCode.Forbidden;
+
+        return Task.CompletedTask;
+    }
+}
+```
+<sup><a href='/src/Snippets.NetCore2x/SampleHandler/SampleHandler.cs#L9-L25' title='File snippet `net-core-2x-sample-handler-with-custom-status-code` was extracted from'>snippet source</a> | <a href='#snippet-net-core-2x-sample-handler-with-custom-status-code' title='Navigate to start of snippet `net-core-2x-sample-handler-with-custom-status-code`'>anchor</a></sup>
+<!-- endsnippet -->
+
+NOTE: Requests handlers are executed in parallel in a non-deterministic way, setting the response code in more than one handler can have unpredictable effects.
+
 ### MVC and Web API support
 
 For information on how to host the Composition Gateway in a ASP.Net COre MVC application, please, refer to the [`ServiceComposer.AspNetCore.Mvc` package](https://github.com/ServiceComposer/ServiceComposer.AspNetCore.Mvc).

README.source.md

@@ -27,6 +27,14 @@ By virtue of leveraging ASP.NET Core 3.x Endpoints ServiceComposer automatically
 
 snippet: net-core-3x-sample-handler-with-authorization
 
+#### Custom HTTP status codes in ASP.NET Core 3.x
+
+The response status code can be set in requests handlers and it'll be honored by the composition pipeline. To set a custom response status code the following snippet can be used:
+
+snippet: net-core-3x-sample-handler-with-custom-status-code
+
+NOTE: Requests handlers are executed in parallel in a non-deterministic way, setting the response code in more than one handler can have unpredictable effects.
+
 ### ASP.NET Core 2.x
 
 Create a new .NET Core console project and add a reference to the following Nuget packages:
@@ -50,6 +58,14 @@ More details on how to implement `IHandleRequests` and `ISubscribeToCompositionE
 * [ViewModel Composition: show me the code!](https://milestone.topics.it/view-model-composition/2019/03/06/viewmodel-composition-show-me-the-code.html)
 * [The ViewModels Lists Composition Dance](https://milestone.topics.it/view-model-composition/2019/03/21/the-viewmodels-lists-composition-dance.html)
 
+#### Custom HTTP status codes in ASP.NET Core 2.x
+
+The response status code can be set in requests handlers and it'll be honored by the composition pipeline. To set a custom response status code the following snippet can be used:
+
+snippet: net-core-2x-sample-handler-with-custom-status-code
+
+NOTE: Requests handlers are executed in parallel in a non-deterministic way, setting the response code in more than one handler can have unpredictable effects.
+
 ### MVC and Web API support
 
 For information on how to host the Composition Gateway in a ASP.Net COre MVC application, please, refer to the [`ServiceComposer.AspNetCore.Mvc` package](https://github.com/ServiceComposer/ServiceComposer.AspNetCore.Mvc).

src/ServiceComposer.AspNetCore.Endpoints.Tests/When_setting_custom_http_status_code.cs

@@ -0,0 +1,62 @@
+using System;
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.DependencyInjection;
+using ServiceComposer.AspNetCore.Testing;
+using Xunit;
+
+namespace ServiceComposer.AspNetCore.Endpoints.Tests
+{
+    public class When_setting_custom_http_status_code
+    {
+        public class CustomStatusCodeHandler : ICompositionRequestsHandler
+        {
+            [HttpGet("/sample/{id}")]
+            public Task Handle(HttpRequest request)
+            {
+                var response = request.HttpContext.Response;
+                response.StatusCode = (int)HttpStatusCode.Forbidden;
+
+                return Task.CompletedTask;
+            }
+        }
+
+        [Fact]
+        public async Task Default_status_code_should_be_overwritten()
+        {
+            // Arrange
+            var expectedStatusCode = HttpStatusCode.Forbidden;
+            var client = new SelfContainedWebApplicationFactoryWithWebHost<When_setting_custom_http_status_code>
+            (
+                configureServices: services =>
+                {
+                    services.AddViewModelComposition(options =>
+                    {
+                        options.AssemblyScanner.Disable();
+                        options.RegisterCompositionHandler<CustomStatusCodeHandler>();
+                    });
+                    services.AddControllers();
+                    services.AddRouting();
+                },
+                configure: app =>
+                {
+                    app.UseRouting();
+                    app.UseEndpoints(builder =>
+                    {
+                        builder.MapCompositionHandlers();
+                        builder.MapControllers();
+                    });
+                }
+            ).CreateClient();
+
+            // Act
+            var composedResponse = await client.GetAsync("/sample/1");
+
+            // Assert
+            Assert.Equal(expectedStatusCode, composedResponse.StatusCode);
+        }
+    }
+}

src/ServiceComposer.AspNetCore.Tests/When_setting_custom_http_status_code.cs

@@ -0,0 +1,60 @@
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Routing;
+using Microsoft.Extensions.DependencyInjection;
+using ServiceComposer.AspNetCore.Gateway;
+using ServiceComposer.AspNetCore.Testing;
+using Xunit;
+
+namespace ServiceComposer.AspNetCore.Tests
+{
+    public class When_setting_custom_http_status_code
+    {
+        class CustomStatusCodeHandler : IHandleRequests
+        {
+            public Task Handle(string requestId, dynamic vm, RouteData routeData, HttpRequest request)
+            {
+                var response = request.HttpContext.Response;
+                response.StatusCode = (int)HttpStatusCode.Forbidden;
+
+                return Task.CompletedTask;
+            }
+
+            public bool Matches(RouteData routeData, string httpVerb, HttpRequest request)
+            {
+                var controller = routeData.Values["controller"]?.ToString();
+                return controller?.ToLowerInvariant() == "custom-status-code";
+            }
+        }
+
+        [Fact]
+        public async Task Default_status_code_should_be_overwritten()
+        {
+            // Arrange
+            var expectedStatusCode = HttpStatusCode.Forbidden;
+            var client = new SelfContainedWebApplicationFactoryWithWebHost<When_setting_custom_http_status_code>
+            (
+                configureServices: services =>
+                {
+                    services.AddViewModelComposition(options =>
+                    {
+                        options.AssemblyScanner.Disable();
+                        options.RegisterRequestsHandler<CustomStatusCodeHandler>();
+                    });
+                    services.AddRouting();
+                },
+                configure: app =>
+                {
+                    app.RunCompositionGatewayWithDefaultRoutes();
+                }
+            ).CreateClient();
+
+            // Act
+            var response = await client.GetAsync("/custom-status-code/1");
+
+            // Assert
+            Assert.Equal(expectedStatusCode, response.StatusCode);
+        }
+    }
+}

src/ServiceComposer.AspNetCore/CompositionEndpointBuilder.cs

@@ -27,15 +27,20 @@ public CompositionEndpointBuilder(RoutePattern routePattern, IEnumerable<Type> c
             Order = order;
             RequestDelegate = async context =>
             {
-                var (viewModel, statusCode) = await CompositionHandler.HandleComposableRequest(context, _compositionHandlers);
-
-                context.Response.StatusCode = statusCode;
-                var json = (string)JsonConvert.SerializeObject(viewModel, GetSettings(context));
-                context.Response.ContentType = "application/json; charset=utf-8";
-                await context.Response.WriteAsync(json);
+                var viewModel = await CompositionHandler.HandleComposableRequest(context, _compositionHandlers);
+                if (viewModel != null)
+                {
+                    var json = (string) JsonConvert.SerializeObject(viewModel, GetSettings(context));
+                    context.Response.ContentType = "application/json; charset=utf-8";
+                    await context.Response.WriteAsync(json);
+                }
+                else
+                {
+                    await context.Response.WriteAsync(string.Empty);
+                }
             };
         }
-        
+
         JsonSerializerSettings GetSettings(HttpContext context)
         {
             if (!context.Request.Headers.TryGetValue("Accept-Casing", out StringValues casing))

src/ServiceComposer.AspNetCore/CompositionHandler.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Primitives;
 using Newtonsoft.Json;
@@ -43,6 +44,8 @@ public class CompositionHandler
 
                 if (pending.Count == 0)
                 {
+                    //we set this here to keep the implementation aligned with the .NET Core 3.x version
+                    context.Response.StatusCode = (int)HttpStatusCode.NotFound;
                     return (null, StatusCodes.Status404NotFound);
                 }
                 else
@@ -75,7 +78,7 @@ public class CompositionHandler
         }
 
 #if NETCOREAPP3_1
-        internal static async Task<(dynamic ViewModel, int StatusCode)> HandleComposableRequest(HttpContext context, Type[] handlerTypes)
+        internal static async Task<dynamic> HandleComposableRequest(HttpContext context, Type[] handlerTypes)
         {
             context.Request.EnableBuffering();
 
@@ -108,7 +111,8 @@ await Task.WhenAll(context.RequestServices.GetServices<IViewModelPreviewHandler>
 
                 if (pending.Count == 0)
                 {
-                    return (null, StatusCodes.Status404NotFound);
+                    context.Response.StatusCode = (int) StatusCodes.Status404NotFound;
+                    return null;
                 }
                 else
                 {
@@ -128,7 +132,7 @@ await Task.WhenAll(context.RequestServices.GetServices<IViewModelPreviewHandler>
                     }
                 }
 
-                return (viewModel, StatusCodes.Status200OK);
+                return viewModel;
             }
             finally
             {

src/ServiceComposer.AspNetCore/CompositionOverControllersActionFilter.cs

@@ -31,26 +31,20 @@ public async Task OnResultExecutionAsync(ResultExecutingContext context, ResultE
 
                 if (handlerTypes.Any())
                 {
-                    var (viewModel, statusCode) = await CompositionHandler.HandleComposableRequest(context.HttpContext, handlerTypes);
+                    var viewModel = await CompositionHandler.HandleComposableRequest(context.HttpContext, handlerTypes);
                     switch (context.Result)
                     {
                         case ViewResult viewResult when viewResult.ViewData.Model == null:
                         {
                             //MVC
-                            if (statusCode == StatusCodes.Status200OK)
-                            {
-                                viewResult.ViewData.Model = viewModel;
-                            }
+                            viewResult.ViewData.Model = viewModel;
 
                             break;
                         }
                         case ObjectResult objectResult when objectResult.Value == null:
                         {
                             //WebAPI
-                            if (statusCode == StatusCodes.Status200OK)
-                            {
-                                objectResult.Value = viewModel;
-                            }
+                            objectResult.Value = viewModel;
 
                             break;
                         }

src/ServiceComposer.AspNetCore/Gateway/Composition.cs

@@ -3,6 +3,7 @@
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
 using System;
+using System.Net;
 using System.Threading.Tasks;
 
 namespace ServiceComposer.AspNetCore.Gateway
@@ -15,15 +16,18 @@ public static async Task HandleRequest(HttpContext context)
             var (viewModel, statusCode) = await CompositionHandler.HandleRequest(requestId, context);
             context.Response.Headers.AddComposedRequestIdHeader(requestId);
 
-            if (statusCode == StatusCodes.Status200OK)
+            //to avoid a breaking change we cannot change the tuple returned by CompositionHandler.HandleRequest
+            //so the only option here is to check if the viewModel is null. View model is null only when there are
+            //no handlers registered for the route, so it's for sure an HTTP404
+            if (viewModel != null)
             {
                 string json = JsonConvert.SerializeObject(viewModel, GetSettings(context));
                 context.Response.ContentType = "application/json; charset=utf-8";
                 await context.Response.WriteAsync(json);
             }
             else
             {
-                context.Response.StatusCode = statusCode;
+                await context.Response.WriteAsync(string.Empty);
             }
         }
 

src/Snippets.NetCore2x/SampleHandler/SampleHandler.cs

@@ -0,0 +1,26 @@
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Routing;
+using ServiceComposer.AspNetCore;
+
+namespace Snippets.NetCore2x.SampleHandler
+{
+    // begin-snippet: net-core-2x-sample-handler-with-custom-status-code
+    public class SampleHandlerWithCustomStatusCode : IHandleRequests
+    {
+        public bool Matches(RouteData routeData, string httpVerb, HttpRequest request)
+        {
+            return true;
+        }
+
+        public Task Handle(string requestId, dynamic vm, RouteData routeData, HttpRequest request)
+        {
+            var response = request.HttpContext.Response;
+            response.StatusCode = (int)HttpStatusCode.Forbidden;
+
+            return Task.CompletedTask;
+        }
+    }
+    // end-snippet
+}