Activate components by default

src/Components/Components/src/ComponentFactory.cs

@@ -5,6 +5,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using Microsoft.AspNetCore.Components.Reflection;
+using Microsoft.Extensions.DependencyInjection;
 using static Microsoft.AspNetCore.Internal.LinkerFlags;
 
 namespace Microsoft.AspNetCore.Components;
@@ -14,46 +15,76 @@ internal sealed class ComponentFactory
     private const BindingFlags _injectablePropertyBindingFlags
         = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
 
-    private static readonly ConcurrentDictionary<Type, Action<IServiceProvider, IComponent>> _cachedInitializers = new();
+    private static readonly ConcurrentDictionary<Type, (Action<IServiceProvider, IComponent> propertyInitializers, ObjectFactory? componentInitializer)> _cachedInitializers = new();
+    private readonly IComponentActivator? _componentActivator;
 
-    private readonly IComponentActivator _componentActivator;
-
-    public ComponentFactory(IComponentActivator componentActivator)
+    public ComponentFactory(IComponentActivator? componentActivator)
     {
-        _componentActivator = componentActivator ?? throw new ArgumentNullException(nameof(componentActivator));
+        _componentActivator = componentActivator;
     }
 
     public static void ClearCache() => _cachedInitializers.Clear();
 
     public IComponent InstantiateComponent(IServiceProvider serviceProvider, [DynamicallyAccessedMembers(Component)] Type componentType)
     {
-        var component = _componentActivator.CreateInstance(componentType);
-        if (component is null)
+        if (_componentActivator is not null)
         {
-            // The default activator will never do this, but an externally-supplied one might
-            throw new InvalidOperationException($"The component activator returned a null value for a component of type {componentType.FullName}.");
+            return InstantiateWithActivator(_componentActivator, serviceProvider, componentType);
         }
 
-        PerformPropertyInjection(serviceProvider, component);
+        return InstantiateDefault(serviceProvider, componentType);
+    }
+
+    private static IComponent InstantiateDefault(IServiceProvider serviceProvider, [DynamicallyAccessedMembers(Component)] Type componentType)
+    {
+        // This is thread-safe because _cachedInitializers is a ConcurrentDictionary.
+        // We might generate the initializer more than once for a given type, but would
+        // still produce the correct result.
+        if (!_cachedInitializers.TryGetValue(componentType, out var initializer))
+        {
+            if (!typeof(IComponent).IsAssignableFrom(componentType))
+            {
+                throw new ArgumentException($"The type {componentType.FullName} does not implement {nameof(IComponent)}.", nameof(componentType));
+            }
+
+            initializer = (CreatePropertyInitializer(componentType), ActivatorUtilities.CreateFactory(componentType, Type.EmptyTypes));
+            _cachedInitializers.TryAdd(componentType, initializer);
+        }
+
+        var (propertyInitializer, componentInitializer) = initializer;
+        var component = (IComponent)componentInitializer!.Invoke(serviceProvider, Array.Empty<object?>());
+        propertyInitializer(serviceProvider, component);
         return component;
     }
 
-    private static void PerformPropertyInjection(IServiceProvider serviceProvider, IComponent instance)
+    private static IComponent InstantiateWithActivator(IComponentActivator componentActivator, IServiceProvider serviceProvider, [DynamicallyAccessedMembers(Component)] Type componentType)
     {
+        var component = componentActivator.CreateInstance(componentType);
+        if (component is null)
+        {
+            // A user implemented IComponentActivator might return null.
+            throw new InvalidOperationException($"The component activator returned a null value for a component of type {componentType.FullName}.");
+        }
+
+        // Use the activated type instead of specified type since the activator may return different/ derived instances.
+        componentType = component.GetType();
+
         // This is thread-safe because _cachedInitializers is a ConcurrentDictionary.
         // We might generate the initializer more than once for a given type, but would
         // still produce the correct result.
-        var instanceType = instance.GetType();
-        if (!_cachedInitializers.TryGetValue(instanceType, out var initializer))
+        if (!_cachedInitializers.TryGetValue(componentType, out var initializer))
         {
-            initializer = CreateInitializer(instanceType);
-            _cachedInitializers.TryAdd(instanceType, initializer);
+            initializer = (CreatePropertyInitializer(componentType), componentInitializer: null);
+            _cachedInitializers.TryAdd(componentType, initializer);
         }
 
-        initializer(serviceProvider, instance);
+        var (propertyInitializer, _) = initializer;
+
+        propertyInitializer(serviceProvider, component);
+        return component;
     }
 
-    private static Action<IServiceProvider, IComponent> CreateInitializer([DynamicallyAccessedMembers(Component)] Type type)
+    private static Action<IServiceProvider, IComponent> CreatePropertyInitializer([DynamicallyAccessedMembers(Component)] Type type)
     {
         // Do all the reflection up front
         List<(string name, Type propertyType, PropertySetter setter)>? injectables = null;

src/Components/Components/src/Microsoft.AspNetCore.Components.WarningSuppressions.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <linker>
-  <assembly fullname="Microsoft.AspNetCore.Components, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
+  <assembly fullname="Microsoft.AspNetCore.Components, Version=7.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>
       <argument>IL2026</argument>
@@ -41,7 +41,7 @@
       <argument>ILLink</argument>
       <argument>IL2072</argument>
       <property name="Scope">member</property>
-      <property name="Target">M:Microsoft.AspNetCore.Components.ComponentFactory.PerformPropertyInjection(System.IServiceProvider,Microsoft.AspNetCore.Components.IComponent)</property>
+      <property name="Target">M:Microsoft.AspNetCore.Components.ComponentFactory.InstantiateWithActivator(Microsoft.AspNetCore.Components.IComponentActivator,System.IServiceProvider,System.Type)</property>
     </attribute>
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>
@@ -59,7 +59,7 @@
       <argument>ILLink</argument>
       <argument>IL2077</argument>
       <property name="Scope">member</property>
-      <property name="Target">M:Microsoft.AspNetCore.Components.ComponentFactory.CreateInitializer(System.Type)</property>
+      <property name="Target">M:Microsoft.AspNetCore.Components.ComponentFactory.CreatePropertyInitializer(System.Type)</property>
     </attribute>
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>

src/Components/Components/src/RenderTree/Renderer.cs

@@ -64,7 +64,7 @@ public event UnhandledExceptionEventHandler UnhandledSynchronizationException
     /// <param name="serviceProvider">The <see cref="IServiceProvider"/> to be used when initializing components.</param>
     /// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
     public Renderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory)
-        : this(serviceProvider, loggerFactory, GetComponentActivatorOrDefault(serviceProvider))
+        : this(serviceProvider, loggerFactory, GetComponentActivatorOrDefault(serviceProvider)!)
     {
         // This overload is provided for back-compatibility
     }
@@ -87,22 +87,16 @@ public Renderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory,
             throw new ArgumentNullException(nameof(loggerFactory));
         }
 
-        if (componentActivator is null)
-        {
-            throw new ArgumentNullException(nameof(componentActivator));
-        }
-
         _serviceProvider = serviceProvider;
         _logger = loggerFactory.CreateLogger<Renderer>();
         _componentFactory = new ComponentFactory(componentActivator);
     }
 
     internal HotReloadManager HotReloadManager { get; set; } = HotReloadManager.Default;
 
-    private static IComponentActivator GetComponentActivatorOrDefault(IServiceProvider serviceProvider)
+    private static IComponentActivator? GetComponentActivatorOrDefault(IServiceProvider serviceProvider)
     {
-        return serviceProvider.GetService<IComponentActivator>()
-            ?? DefaultComponentActivator.Instance;
+        return serviceProvider.GetService<IComponentActivator>();
     }
 
     /// <summary>

src/Components/Components/test/ComponentFactoryTest.cs

@@ -12,7 +12,7 @@ public void InstantiateComponent_CreatesInstance()
     {
         // Arrange
         var componentType = typeof(EmptyComponent);
-        var factory = new ComponentFactory(new DefaultComponentActivator());
+        var factory = new ComponentFactory(null);
 
         // Act
         var instance = factory.InstantiateComponent(GetServiceProvider(), componentType);
@@ -22,12 +22,30 @@ public void InstantiateComponent_CreatesInstance()
         Assert.IsType<EmptyComponent>(instance);
     }
 
+    [Fact]
+    public void InstantiateComponent_CreatesInstance_WithTypeActivation()
+    {
+        // Arrange
+        var componentType = typeof(ComponentWithConstructorInjection);
+        var factory = new ComponentFactory(null);
+
+        // Act
+        var instance = factory.InstantiateComponent(GetServiceProvider(), componentType);
+
+        // Assert
+        Assert.NotNull(instance);
+        var component = Assert.IsType<ComponentWithConstructorInjection>(instance);
+        Assert.NotNull(component.Property1);
+        Assert.NotNull(component.Property2);
+        Assert.NotNull(component.Property3); // Property injection should still work.
+    }
+
     [Fact]
     public void InstantiateComponent_CreatesInstance_NonComponent()
     {
         // Arrange
         var componentType = typeof(List<string>);
-        var factory = new ComponentFactory(new DefaultComponentActivator());
+        var factory = new ComponentFactory(null);
 
         // Assert
         var ex = Assert.Throws<ArgumentException>(() => factory.InstantiateComponent(GetServiceProvider(), componentType));
@@ -95,7 +113,7 @@ public void InstantiateComponent_IgnoresPropertiesWithoutInjectAttribute()
     {
         // Arrange
         var componentType = typeof(ComponentWithNonInjectableProperties);
-        var factory = new ComponentFactory(new DefaultComponentActivator());
+        var factory = new ComponentFactory(null);
 
         // Act
         var instance = factory.InstantiateComponent(GetServiceProvider(), componentType);
@@ -129,6 +147,31 @@ public Task SetParametersAsync(ParameterView parameters)
         }
     }
 
+    public class ComponentWithConstructorInjection : IComponent
+    {
+        public ComponentWithConstructorInjection(TestService1 property1, TestService2 property2)
+        {
+            Property1 = property1;
+            Property2 = property2;
+        }
+
+        public TestService1 Property1 { get; }
+        public TestService2 Property2 { get; }
+
+        [Inject]
+        public TestService2 Property3 { get; set; }
+
+        public void Attach(RenderHandle renderHandle)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task SetParametersAsync(ParameterView parameters)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
     private class ComponentWithInjectProperties : IComponent
     {
         [Inject]

src/Components/Forms/src/Microsoft.AspNetCore.Components.Forms.WarningSuppressions.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <linker>
-  <assembly fullname="Microsoft.AspNetCore.Components.Forms, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
+  <assembly fullname="Microsoft.AspNetCore.Components.Forms, Version=7.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>
       <argument>IL2026</argument>

src/Components/Samples/BlazorServerApp/Pages/FetchData.razor

@@ -3,7 +3,6 @@
 <PageTitle>Weather forecast</PageTitle>
 
 @using BlazorServerApp.Data
-@inject WeatherForecastService ForecastService
 
 <h1>Weather forecast</h1>
 
@@ -41,6 +40,13 @@ else
 @code {
     WeatherForecast[]? forecasts;
 
+    public FetchData(WeatherForecastService forecastService)
+    {
+        ForecastService = forecastService;
+    }
+
+    private WeatherForecastService ForecastService { get; }
+
     protected override async Task OnInitializedAsync()
     {
         forecasts = await ForecastService.GetForecastAsync(DateTime.Now);

src/Components/Web/src/Microsoft.AspNetCore.Components.Web.WarningSuppressions.xml

@@ -1,18 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <linker>
-  <assembly fullname="Microsoft.AspNetCore.Components.Web, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
-    <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
-      <argument>ILLink</argument>
-      <argument>IL2026</argument>
-      <property name="Scope">member</property>
-      <property name="Target">M:Microsoft.AspNetCore.Components.Web.Infrastructure.JSComponentInterop.SetRootComponentParameters(System.Int32,System.Int32,System.Text.Json.JsonElement,System.Text.Json.JsonSerializerOptions)</property>
-    </attribute>
-    <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
-      <argument>ILLink</argument>
-      <argument>IL2026</argument>
-      <property name="Scope">member</property>
-      <property name="Target">M:Microsoft.AspNetCore.Components.Web.WebEventData.ParseEventArgsJson(Microsoft.AspNetCore.Components.RenderTree.Renderer,System.Text.Json.JsonSerializerOptions,System.UInt64,System.String,System.Text.Json.JsonElement)</property>
-    </attribute>
+  <assembly fullname="Microsoft.AspNetCore.Components.Web, Version=7.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>
       <argument>IL2062</argument>

src/Components/WebAssembly/WebAssembly.Authentication/src/Microsoft.AspNetCore.Components.WebAssembly.Authentication.WarningSuppressions.xml

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <linker>
   <assembly fullname="Microsoft.AspNetCore.Components.WebAssembly.Authentication, Version=42.42.42.42, Culture=neutral, PublicKeyToken=adb9793829ddae60">
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
@@ -14,4 +14,4 @@
       <property name="Target">M:Microsoft.Extensions.DependencyInjection.WebAssemblyAuthenticationServiceCollectionExtensions.&lt;&gt;c__1`1.&lt;AddAuthenticationStateProvider&gt;b__1_0(System.IServiceProvider)</property>
     </attribute>
   </assembly>
-</linker>
+</linker>

src/JSInterop/Microsoft.JSInterop/src/Microsoft.JSInterop.WarningSuppressions.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <linker>
-  <assembly fullname="Microsoft.JSInterop, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
+  <assembly fullname="Microsoft.JSInterop, Version=7.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60">
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>
       <argument>IL2026</argument>