Add change tracking support for shadow navigations to non-shadow entity types

src/EFCore/ChangeTracking/CollectionEntry.cs

@@ -8,7 +8,6 @@
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
 using Microsoft.EntityFrameworkCore.Metadata;
-using Microsoft.EntityFrameworkCore.Metadata.Internal;
 
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
@@ -117,6 +116,6 @@ public override IQueryable Query()
         ///     directly from your code. This API may change or be removed in future releases.
         /// </summary>
         protected virtual void EnsureInitialized()
-            => Metadata.GetCollectionAccessor().GetOrCreate(InternalEntry.Entity);
+            => InternalEntry.GetOrCreateCollection(Metadata);
     }
 }

src/EFCore/ChangeTracking/Internal/EmptyShadowValuesFactoryFactory.cs

@@ -18,7 +18,7 @@ public class EmptyShadowValuesFactoryFactory : SnapshotFactoryFactory
         ///     directly from your code. This API may change or be removed in future releases.
         /// </summary>
         protected override int GetPropertyIndex(IPropertyBase propertyBase)
-            => (propertyBase as IProperty)?.GetShadowIndex() ?? -1;
+            => propertyBase.GetShadowIndex();
 
         /// <summary>
         ///     This API supports the Entity Framework Core infrastructure and is not intended to be used

src/EFCore/ChangeTracking/Internal/InternalEntityEntry.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;
@@ -522,6 +522,50 @@ protected virtual void WritePropertyValue([NotNull] IPropertyBase propertyBase,
             propertyBase.GetSetter().SetClrValue(Entity, value);
         }
 
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public virtual object GetOrCreateCollection([NotNull] INavigation navigation)
+        {
+            Debug.Assert(!navigation.IsShadowProperty);
+
+            return navigation.GetCollectionAccessor().GetOrCreate(Entity);
+        }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public virtual bool CollectionContains([NotNull] INavigation navigation, [NotNull] InternalEntityEntry value)
+        {
+            Debug.Assert(!navigation.IsShadowProperty);
+
+            return navigation.GetCollectionAccessor().Contains(Entity, value.Entity);
+        }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public virtual bool AddToCollection([NotNull] INavigation navigation, [NotNull] InternalEntityEntry value)
+        {
+            Debug.Assert(!navigation.IsShadowProperty);
+
+            return navigation.GetCollectionAccessor().Add(Entity, value.Entity);
+        }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public virtual void RemoveFromCollection([NotNull] INavigation navigation, [NotNull] InternalEntityEntry value)
+        {
+            Debug.Assert(!navigation.IsShadowProperty);
+
+            navigation.GetCollectionAccessor().Remove(Entity, value.Entity);
+        }
+
         /// <summary>
         ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
         ///     directly from your code. This API may change or be removed in future releases.
@@ -673,9 +717,7 @@ public virtual object this[[NotNull] IPropertyBase propertyBase]
         {
             get
             {
-                return propertyBase is INavigation && propertyBase.IsShadowProperty // Remove when issue #749 is fixed
-                    ? null
-                    : _storeGeneratedValues.TryGetValue(propertyBase, out var value)
+                return _storeGeneratedValues.TryGetValue(propertyBase, out var value)
                         ? value
                         : ReadPropertyValue(propertyBase);
             }

src/EFCore/ChangeTracking/Internal/InternalEntityEntrySubscriber.cs

@@ -9,6 +9,7 @@
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Metadata.Internal;
 
+// ReSharper disable ParameterOnlyUsedForPreconditionCheck.Local
 namespace Microsoft.EntityFrameworkCore.ChangeTracking.Internal
 {
     /// <summary>
@@ -90,8 +91,7 @@ private static INotifyCollectionChanged AsINotifyCollectionChanged(
             IEntityType entityType,
             ChangeTrackingStrategy changeTrackingStrategy)
         {
-            var notifyingCollection = navigation.GetCollectionAccessor().GetOrCreate(entry.Entity) as INotifyCollectionChanged;
-            if (notifyingCollection == null)
+            if (!(navigation.GetCollectionAccessor()?.GetOrCreate(entry.Entity) is INotifyCollectionChanged notifyingCollection))
             {
                 throw new InvalidOperationException(
                     CoreStrings.NonNotifyingCollection(navigation.Name, entityType.DisplayName(), changeTrackingStrategy));
@@ -105,8 +105,7 @@ private static INotifyPropertyChanged AsINotifyPropertyChanged(
             IEntityType entityType,
             ChangeTrackingStrategy changeTrackingStrategy)
         {
-            var changed = entry.Entity as INotifyPropertyChanged;
-            if (changed == null)
+            if (!(entry.Entity is INotifyPropertyChanged changed))
             {
                 throw new InvalidOperationException(
                     CoreStrings.ChangeTrackingInterfaceMissing(
@@ -121,8 +120,7 @@ private static INotifyPropertyChanging AsINotifyPropertyChanging(
             IEntityType entityType,
             ChangeTrackingStrategy changeTrackingStrategy)
         {
-            var changing = entry.Entity as INotifyPropertyChanging;
-            if (changing == null)
+            if (!(entry.Entity is INotifyPropertyChanging changing))
             {
                 throw new InvalidOperationException(
                     CoreStrings.ChangeTrackingInterfaceMissing(

src/EFCore/ChangeTracking/Internal/InternalMixedEntityEntry.cs

@@ -1,6 +1,8 @@
 // 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.Collections;
+using System.Collections.Generic;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Metadata.Internal;
@@ -85,5 +87,76 @@ protected override void WritePropertyValue(IPropertyBase propertyBase, object va
                 _shadowValues[propertyBase.GetShadowIndex()] = value;
             }
         }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override object GetOrCreateCollection(INavigation navigation)
+            => navigation.IsShadowProperty
+                ? GetOrCreateCollectionTyped(navigation)
+                : base.GetOrCreateCollection(navigation);
+
+        private ICollection<object> GetOrCreateCollectionTyped(INavigation navigation)
+        {
+            if (!(_shadowValues[navigation.GetShadowIndex()] is ICollection<object> collection))
+            {
+                collection = new HashSet<object>();
+                _shadowValues[navigation.GetShadowIndex()] = collection;
+            }
+
+            return collection;
+        }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override bool CollectionContains(INavigation navigation, InternalEntityEntry value)
+            => navigation.IsShadowProperty
+                ? GetOrCreateCollectionTyped(navigation).Contains(value.Entity)
+                : base.CollectionContains(navigation, value);
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override bool AddToCollection(INavigation navigation, InternalEntityEntry value)
+        {
+            if (!navigation.IsShadowProperty)
+            {
+                return base.AddToCollection(navigation, value);
+            }
+
+            if (navigation.GetTargetType().ClrType == null)
+            {
+                return false;
+            }
+
+            var collection = GetOrCreateCollectionTyped(navigation);
+            if (!collection.Contains(value.Entity))
+            {
+                collection.Add(value.Entity);
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override void RemoveFromCollection(INavigation navigation, InternalEntityEntry value)
+        {
+            if (navigation.IsShadowProperty)
+            {
+                GetOrCreateCollectionTyped(navigation).Remove(value.Entity);
+            }
+            else
+            {
+                base.RemoveFromCollection(navigation, value);
+            }
+        }
     }
 }

src/EFCore/ChangeTracking/Internal/InternalShadowEntityEntry.cs

@@ -1,6 +1,8 @@
 // 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.Collections;
+using System.Collections.Generic;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Metadata.Internal;
@@ -70,5 +72,58 @@ protected override object ReadPropertyValue(IPropertyBase propertyBase)
         /// </summary>
         protected override void WritePropertyValue(IPropertyBase propertyBase, object value)
             => _propertyValues[propertyBase.GetShadowIndex()] = value;
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override object GetOrCreateCollection(INavigation navigation)
+            => GetOrCreateCollectionTyped(navigation);
+
+        private ICollection<object> GetOrCreateCollectionTyped(INavigation navigation)
+        {
+            if (!(_propertyValues[navigation.GetShadowIndex()] is ICollection<object> collection))
+            {
+                collection = new HashSet<object>();
+                _propertyValues[navigation.GetShadowIndex()] = collection;
+            }
+
+            return collection;
+        }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override bool CollectionContains(INavigation navigation, InternalEntityEntry value)
+            => GetOrCreateCollectionTyped(navigation).Contains(value.Entity);
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override bool AddToCollection(INavigation navigation, InternalEntityEntry value)
+        {
+            if (navigation.GetTargetType().ClrType == null)
+            {
+                return false;
+            }
+
+            var collection = GetOrCreateCollectionTyped(navigation);
+            if (!collection.Contains(value.Entity))
+            {
+                collection.Add(value.Entity);
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
+        ///     directly from your code. This API may change or be removed in future releases.
+        /// </summary>
+        public override void RemoveFromCollection(INavigation navigation, InternalEntityEntry value)
+            => GetOrCreateCollectionTyped(navigation).Remove(value.Entity);
     }
 }

src/EFCore/ChangeTracking/Internal/KeyPropagator.cs

@@ -100,10 +100,9 @@ private static InternalEntityEntry TryPropagateValue(InternalEntityEntry entry,
                 {
                     if (property == foreignKey.Properties[propertyIndex])
                     {
-                        // Remove when issue #749 is fixed
-                        var principal = foreignKey.DependentToPrincipal?.IsShadowProperty ?? true
+                        var principal = foreignKey.DependentToPrincipal == null
                             ? null
-                            : foreignKey.DependentToPrincipal.GetGetter().GetClrValue(entry.Entity);
+                            : entry[foreignKey.DependentToPrincipal];
                         InternalEntityEntry principalEntry = null;
                         if (principal != null)
                         {