Controllers, ViewComponents, PageModels, and TagHelpers can now be resolved with ScopedLifestyle.Flowing. Fixes #33

Author: dotnetjunkie

src/SimpleInjector.Integration.AspNetCore.Mvc.Core/SimpleInjectorControllerActivator.cs

@@ -12,8 +12,7 @@ namespace SimpleInjector.Integration.AspNetCore.Mvc
     /// <summary>Controller activator for Simple Injector.</summary>
     public sealed class SimpleInjectorControllerActivator : IControllerActivator
     {
-        private readonly ConcurrentDictionary<Type, InstanceProducer?> controllerProducers =
-            new ConcurrentDictionary<Type, InstanceProducer?>();
+        private readonly ConcurrentDictionary<Type, InstanceProducer?> controllerProducers = new();
 
         private readonly Container container;
 
@@ -56,7 +55,13 @@ public object Create(ControllerContext context)
                     $"https://docs.microsoft.com/en-us/aspnet/core/mvc/advanced/app-parts.");
             }
 
-            return producer.GetInstance();
+            var scope = context.HttpContext.GetScope();
+
+            // Scope will be null when the core integration's RequestScopingStartupFilter didn't run. This
+            // can happen if this activator is used without the application being configured using the
+            // SimpleInjectorAddOptions.AddAspNetCore() extension method. In that case we call .GetInstance()
+            // and expect the scoping to run using the default ambient scoping mechanism (non flowing).
+            return scope is null ? producer.GetInstance() : producer.GetInstance(scope);
         }
 
         /// <summary>Releases the controller.</summary>

src/SimpleInjector.Integration.AspNetCore.Mvc.ViewFeatures/SimpleInjectorViewComponentActivator.cs

@@ -56,7 +56,13 @@ public object Create(ViewComponentContext context)
                         viewComponentType.FullName));
             }
 
-            return producer.GetInstance();
+            var scope = context.ViewContext.HttpContext.GetScope();
+
+            // Scope will be null when the core integration's RequestScopingStartupFilter didn't run. This
+            // can happen if this activator is used without the application being configured using the
+            // SimpleInjectorAddOptions.AddAspNetCore() extension method. In that case we call .GetInstance()
+            // and expect the scoping to run using the default ambient scoping mechanism (non flowing).
+            return scope is null ? producer.GetInstance() : producer.GetInstance(scope);
         }
 
         /// <summary>Releases the view component.</summary>

src/SimpleInjector.Integration.AspNetCore.Mvc/SimpleInjectorPageModelActivatorProvider.cs

@@ -69,8 +69,17 @@ public Func<PageContext, object> CreateActivator(CompiledPageActionDescriptor de
                         Environment.NewLine,
                         pageModelType.FullName));
             }
-            
-            return _ => producer.GetInstance();
+
+            return context =>
+            {
+                var scope = context.HttpContext.GetScope();
+
+                // Scope will be null when the core integration's RequestScopingStartupFilter didn't run. This
+                // can happen if this activator is used without the application being configured using the
+                // SimpleInjectorAddOptions.AddAspNetCore() extension method. In that case we call .GetInstance()
+                // and expect the scoping to run using the default ambient scoping mechanism (non flowing).
+                return scope is null ? producer.GetInstance() : producer.GetInstance(scope);
+            };
         }
 
         /// <summary>

src/SimpleInjector.Integration.AspNetCore.Mvc/SimpleInjectorTagHelperActivator.cs

@@ -13,8 +13,7 @@ namespace SimpleInjector.Integration.AspNetCore.Mvc
     /// <summary>Tag Helper Activator for Simple Injector.</summary>
     public class SimpleInjectorTagHelperActivator : ITagHelperActivator
     {
-        private readonly ConcurrentDictionary<Type, InstanceProducer> tagHelperProducers =
-            new ConcurrentDictionary<Type, InstanceProducer>();
+        private readonly ConcurrentDictionary<Type, InstanceProducer> tagHelperProducers = new();
 
         private readonly Container container;
         private readonly Predicate<Type> tagHelperSelector;
@@ -41,13 +40,23 @@ public SimpleInjectorTagHelperActivator(
         /// <inheritdoc />
         public TTagHelper Create<TTagHelper>(ViewContext context) where TTagHelper : ITagHelper =>
             this.UseSimpleInjector(typeof(TTagHelper))
-                ? (TTagHelper)this.GetInstanceFromSimpleInjector(typeof(TTagHelper))
+                ? (TTagHelper)this.GetInstanceFromSimpleInjector(typeof(TTagHelper), context)
                 : this.activator.Create<TTagHelper>(context);
 
         private bool UseSimpleInjector(Type type) => this.tagHelperSelector.Invoke(type);
 
-        private object GetInstanceFromSimpleInjector(Type type) =>
-            this.tagHelperProducers.GetOrAdd(type, this.GetTagHelperProducer).GetInstance();
+        private object GetInstanceFromSimpleInjector(Type type, ViewContext context)
+        {
+            var scope = context.HttpContext.GetScope();
+
+            var producer = this.tagHelperProducers.GetOrAdd(type, this.GetTagHelperProducer);
+
+            // Scope will be null when the core integration's RequestScopingStartupFilter didn't run. This
+            // can happen if this activator is used without the application being configured using the
+            // SimpleInjectorAddOptions.AddAspNetCore() extension method. In that case we call .GetInstance()
+            // and expect the scoping to run using the default ambient scoping mechanism (non flowing).
+            return scope is null ? producer.GetInstance() : producer.GetInstance(scope);
+        }
 
         // Find the registration for the tag helper in the container
         // and fallback to creating one when no registration exists.

src/SimpleInjector.Integration.AspNetCore/OnePerNestedScopeServiceProviderAccessor.cs

@@ -24,9 +24,9 @@ internal OnePerNestedScopeServiceProviderAccessor(Container container, IServiceP
 
         // Only the scope wrapping the request (the root scope) contains the HttpContext in its Items dictionary.
         // With nested scopes, this property returns null.
-        private HttpContext? RootScopeHttpContext =>
-            this.CurrentScope?.GetItem(RequestScopingStartupFilter.HttpContextKey) as HttpContext;
+        private HttpContext? RootScopeHttpContext => this.CurrentScope?.GetHttpContext();
 
+        // TODO: How to handle this?
         private Scope? CurrentScope => Lifestyle.Scoped.GetCurrentScope(this.container);
     }
 }

src/SimpleInjector.Integration.AspNetCore/RequestScopingStartupFilter.cs

@@ -11,8 +11,6 @@ namespace SimpleInjector.Integration.AspNetCore
 
     internal sealed class RequestScopingStartupFilter : IStartupFilter
     {
-        internal static readonly object HttpContextKey = new object();
-
         private readonly Container container;
 
         public RequestScopingStartupFilter(Container container)
@@ -32,13 +30,17 @@ public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
 
         private void ConfigureRequestScoping(IApplicationBuilder builder)
         {
+            bool flowing = this.container.Options.DefaultScopedLifestyle == ScopedLifestyle.Flowing;
+
             builder.Use(async (httpContext, next) =>
             {
-                Scope scope = AsyncScopedLifestyle.BeginScope(this.container);
+                Scope scope = flowing
+                    ? new(this.container)
+                    : AsyncScopedLifestyle.BeginScope(this.container);
 
                 try
                 {
-                    scope.SetItem(HttpContextKey, httpContext);
+                    httpContext.ConnectToScope(scope);
 
                     await next();
                 }

src/SimpleInjector.Integration.AspNetCore/SimpleInjectorHttpContextExtensions.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Simple Injector Contributors. All rights reserved.
+// Licensed under the MIT License. See LICENSE file in the project root for license information.
+
+namespace SimpleInjector.Integration.AspNetCore
+{
+    using Microsoft.AspNetCore.Http;
+    using SimpleInjector;
+
+    /// <summary>
+    /// Extension methods on top of HttpContext
+    /// </summary>
+    public static class SimpleInjectorHttpContextExtensions
+    {
+        private static readonly object HttpContextKey = new();
+
+        /// <summary>
+        /// Gets the <see cref="Scope"/> connected to the supplied <see cref="HttpContext"/>.
+        /// </summary>
+        /// <param name="httpContext">The <see cref="HttpContext"/> to retrieve the <see cref="Scope"/> from.</param>
+        /// <returns>The scope or null.</returns>
+        public static Scope? GetScope(this HttpContext httpContext) => (Scope)httpContext.Items[HttpContextKey];
+
+        internal static HttpContext? GetHttpContext(this Scope scope) => scope.GetItem(HttpContextKey) as HttpContext;
+
+        internal static void ConnectToScope(this HttpContext httpContext, Scope scope)
+        {
+            scope.SetItem(HttpContextKey, httpContext);
+            httpContext.Items[HttpContextKey] = scope;
+        }
+    }
+}