trying to fix 1009 by changing the AssignToProperties method behavior

src/Microsoft.AspNetCore.Components/CascadingValue.cs

@@ -58,7 +58,7 @@ public void Init(RenderHandle renderHandle)
         public void SetParameters(ParameterCollection parameters)
         {
             // Implementing the parameter binding manually, instead of just calling
-            // parameters.AssignToProperties(this), is just a very slight perf optimization
+            // parameters.SetParameterProperties(this), is just a very slight perf optimization
             // and makes it simpler impose rules about the params being required or not.
 
             var hasSuppliedValue = false;

src/Microsoft.AspNetCore.Components/ComponentBase.cs

@@ -151,7 +151,7 @@ void IComponent.Init(RenderHandle renderHandle)
         /// <param name="parameters">The parameters to apply.</param>
         public virtual void SetParameters(ParameterCollection parameters)
         {
-            parameters.AssignToProperties(this);
+            parameters.SetParameterProperties(this);
 
             if (!_hasCalledInit)
             {

src/Microsoft.AspNetCore.Components/Layouts/LayoutDisplay.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -42,7 +42,7 @@ public void Init(RenderHandle renderHandle)
         /// <inheritdoc />
         public void SetParameters(ParameterCollection parameters)
         {
-            parameters.AssignToProperties(this);
+            parameters.SetParameterProperties(this);
             Render();
         }
 

src/Microsoft.AspNetCore.Components/ParameterCollectionExtensions.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Linq;
 using System.Reflection;
 
 namespace Microsoft.AspNetCore.Components
@@ -16,18 +17,15 @@ public static class ParameterCollectionExtensions
     {
         private const BindingFlags _bindablePropertyFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.IgnoreCase;
 
-        private delegate void WriteParameterAction(object target, object parameterValue);
-
-        private readonly static IDictionary<Type, IDictionary<string, WriteParameterAction>> _cachedParameterWriters
-            = new ConcurrentDictionary<Type, IDictionary<string, WriteParameterAction>>();
+        private readonly static IDictionary<Type, IDictionary<string, IPropertySetter>> _cachedParameterWriters = new ConcurrentDictionary<Type, IDictionary<string, IPropertySetter>>();
 
         /// <summary>
         /// Iterates through the <see cref="ParameterCollection"/>, assigning each parameter
         /// to a property of the same name on <paramref name="target"/>.
         /// </summary>
         /// <param name="parameterCollection">The <see cref="ParameterCollection"/>.</param>
         /// <param name="target">An object that has a public writable property matching each parameter's name and type.</param>
-        public static void AssignToProperties(
+        public static void SetParameterProperties(
             in this ParameterCollection parameterCollection,
             object target)
         {
@@ -43,6 +41,8 @@ public static void AssignToProperties(
                 _cachedParameterWriters[targetType] = parameterWriters;
             }
 
+            var localParameterWriter = parameterWriters.Values.ToList();
+
             foreach (var parameter in parameterCollection)
             {
                 var parameterName = parameter.Name;
@@ -53,7 +53,8 @@ public static void AssignToProperties(
 
                 try
                 {
-                    parameterWriter(target, parameter.Value);
+                    parameterWriter.SetValue(target, parameter.Value);
+                    localParameterWriter.Remove(parameterWriter);
                 }
                 catch (Exception ex)
                 {
@@ -62,14 +63,19 @@ public static void AssignToProperties(
                         $"type '{target.GetType().FullName}'. The error was: {ex.Message}", ex);
                 }
             }
+
+            foreach (var nonUsedParameter in localParameterWriter)
+            {
+                nonUsedParameter.SetValue(target, nonUsedParameter.GetDefaultValue());
+            }
         }
 
         internal static IEnumerable<PropertyInfo> GetCandidateBindableProperties(Type targetType)
             => MemberAssignment.GetPropertiesIncludingInherited(targetType, _bindablePropertyFlags);
 
-        private static IDictionary<string, WriteParameterAction> CreateParameterWriters(Type targetType)
+        private static IDictionary<string, IPropertySetter> CreateParameterWriters(Type targetType)
         {
-            var result = new Dictionary<string, WriteParameterAction>(StringComparer.OrdinalIgnoreCase);
+            var result = new Dictionary<string, IPropertySetter>(StringComparer.OrdinalIgnoreCase);
 
             foreach (var propertyInfo in GetCandidateBindableProperties(targetType))
             {
@@ -90,10 +96,7 @@ private static IDictionary<string, WriteParameterAction> CreateParameterWriters(
                         $"name '{propertyName.ToLowerInvariant()}'. Parameter names are case-insensitive and must be unique.");
                 }
 
-                result.Add(propertyName, (object target, object parameterValue) =>
-                {
-                    propertySetter.SetValue(target, parameterValue);
-                });
+                result.Add(propertyName, propertySetter);
             }
 
             return result;

src/Microsoft.AspNetCore.Components/Reflection/IPropertySetter.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -8,5 +8,7 @@ namespace Microsoft.AspNetCore.Components.Reflection
     internal interface IPropertySetter
     {
         void SetValue(object target, object value);
+
+        object GetDefaultValue();
     }
 }

src/Microsoft.AspNetCore.Components/Reflection/MemberAssignment.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -43,15 +43,23 @@ public static IPropertySetter CreatePropertySetter(Type targetType, PropertyInfo
         class PropertySetter<TTarget, TValue> : IPropertySetter
         {
             private readonly Action<TTarget, TValue> _setterDelegate;
+            private object _defaultValue;
 
             public PropertySetter(MethodInfo setMethod)
             {
                 _setterDelegate = (Action<TTarget, TValue>)Delegate.CreateDelegate(
                     typeof(Action<TTarget, TValue>), setMethod);
+                var propertyType = typeof(TValue);
+                _defaultValue = propertyType.IsValueType ? Activator.CreateInstance(propertyType) : null;
             }
 
             public void SetValue(object target, object value)
                 => _setterDelegate((TTarget)target, (TValue)value);
+
+            public object GetDefaultValue()
+            {
+                return _defaultValue;
+            }
         }
     }
 }

src/Microsoft.AspNetCore.Components/Routing/Router.cs

@@ -45,7 +45,7 @@ public void Init(RenderHandle renderHandle)
         /// <inheritdoc />
         public void SetParameters(ParameterCollection parameters)
         {
-            parameters.AssignToProperties(this);
+            parameters.SetParameterProperties(this);
             var types = ComponentResolver.ResolveComponents(AppAssembly);
             Routes = RouteTable.Create(types);
             Refresh();

test/Microsoft.AspNetCore.Components.Test/ParameterCollectionAssignmentExtensionsTest.cs

@@ -27,7 +27,7 @@ public void IncomingParameterMatchesAnnotatedPrivateProperty_SetsValue()
             var target = new HasInstanceProperties();
 
             // Act
-            parameterCollection.AssignToProperties(target);
+            parameterCollection.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(123, target.IntProp);
@@ -46,7 +46,7 @@ public void IncomingParameterMatchesDeclaredParameterCaseInsensitively_SetsValue
             var target = new HasInstanceProperties();
 
             // Act
-            parameterCollection.AssignToProperties(target);
+            parameterCollection.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(123, target.IntProp);
@@ -64,15 +64,15 @@ public void IncomingParameterMatchesInheritedDeclaredParameter_SetsValue()
             var target = new HasInheritedProperties();
 
             // Act
-            parameterCollection.AssignToProperties(target);
+            parameterCollection.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(123, target.IntProp);
             Assert.Equal(456, target.DerivedClassIntProp);
         }
 
         [Fact]
-        public void NoIncomingParameterMatchesDeclaredParameter_LeavesValueUnchanged()
+        public void NoIncomingParameterMatchesDeclaredParameter_SetValuesDefault()
         {
             // Arrange
             var existingObjectValue = new object();
@@ -86,12 +86,12 @@ public void NoIncomingParameterMatchesDeclaredParameter_LeavesValueUnchanged()
             var parameterCollection = new ParameterCollectionBuilder().Build();
 
             // Act
-            parameterCollection.AssignToProperties(target);
+            parameterCollection.SetParameterProperties(target);
 
             // Assert
-            Assert.Equal(456, target.IntProp);
-            Assert.Equal("Existing value", target.StringProp);
-            Assert.Same(existingObjectValue, target.ObjectPropCurrentValue);
+            Assert.Equal(0, target.IntProp);
+            Assert.Null(target.StringProp);
+            Assert.Null(target.ObjectPropCurrentValue);
         }
 
         [Fact]
@@ -106,7 +106,7 @@ public void IncomingParameterMatchesNoDeclaredParameter_Throws()
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.AssignToProperties(target));
+                () => parameterCollection.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -127,7 +127,7 @@ public void IncomingParameterMatchesPropertyNotDeclaredAsParameter_Throws()
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.AssignToProperties(target));
+                () => parameterCollection.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(default, target.IntProp);
@@ -150,7 +150,7 @@ public void IncomingParameterValueMismatchesDeclaredParameterType_Throws()
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.AssignToProperties(target));
+                () => parameterCollection.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -171,7 +171,7 @@ public void PropertyExplicitSetterException_Throws()
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.AssignToProperties(target));
+                () => parameterCollection.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -189,7 +189,7 @@ public void DeclaredParametersVaryOnlyByCase_Throws()
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(() =>
-                parameterCollection.AssignToProperties(target));
+                parameterCollection.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -205,14 +205,14 @@ public void DeclaredParameterClashesWithInheritedParameter_Throws()
             // an allowed scenario because there would be no way for the consumer to specify
             // both property values, and it's no good leaving the shadowed one unset because the
             // base class can legitimately depend on it for correct functioning.
-            
+
             // Arrange
             var parameterCollection = new ParameterCollectionBuilder().Build();
             var target = new HasParameterClashingWithInherited();
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(() =>
-                parameterCollection.AssignToProperties(target));
+                parameterCollection.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -226,7 +226,7 @@ class HasInstanceProperties
         {
             // "internal" to show we're not requiring public accessors, but also
             // to keep the assertions simple in the tests
-            
+
             [Parameter] internal int IntProp { get; set; }
             [Parameter] internal string StringProp { get; set; }
 

test/Microsoft.AspNetCore.Components.Test/RenderTreeDiffBuilderTest.cs

@@ -1557,7 +1557,7 @@ private class FakeComponent : IComponent
             public void Init(RenderHandle renderHandle) { }
             public void SetParameters(ParameterCollection parameters)
             {
-                parameters.AssignToProperties(this);
+                parameters.SetParameterProperties(this);
             }
         }
 

test/Microsoft.AspNetCore.Components.Test/RendererTest.cs

@@ -1202,7 +1202,7 @@ public void Init(RenderHandle renderHandle)
                 => RenderHandle = renderHandle;
 
             public void SetParameters(ParameterCollection parameters)
-                => parameters.AssignToProperties(this);
+                => parameters.SetParameterProperties(this);
         }
 
         private class EventComponent : AutoRenderComponent, IComponent, IHandleEvent
@@ -1310,7 +1310,7 @@ public void Init(RenderHandle renderHandle)
 
             public void SetParameters(ParameterCollection parameters)
             {
-                parameters.AssignToProperties(this);
+                parameters.SetParameterProperties(this);
                 Render();
             }
 

test/shared/AutoRenderComponent.cs

@@ -17,7 +17,7 @@ public void Init(RenderHandle renderHandle)
 
         public virtual void SetParameters(ParameterCollection parameters)
         {
-            parameters.AssignToProperties(this);
+            parameters.SetParameterProperties(this);
             TriggerRender();
         }