Thanksgiving project: lookup entities by primary key, alternate key, or foreign key

src/EFCore/ChangeTracking/IPrincipalKeyValueFactory`.cs

@@ -20,11 +20,11 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking;
 public interface IPrincipalKeyValueFactory<TKey> : IPrincipalKeyValueFactory
 {
     /// <summary>
-    ///     Creates a key object from key values obtained in-order from the given array.
+    ///     Creates a key object from key values obtained in-order from the given enumerable.
     /// </summary>
     /// <param name="keyValues">The key values.</param>
     /// <returns>The key object, or null if any of the key values were null.</returns>
-    object? CreateFromKeyValues(object?[] keyValues);
+    object? CreateFromKeyValues(IReadOnlyList<object?> keyValues);
 
     /// <summary>
     ///     Creates a key object from key values obtained from their indexed position in the given <see cref="ValueBuffer" />.
@@ -38,7 +38,7 @@ public interface IPrincipalKeyValueFactory<TKey> : IPrincipalKeyValueFactory
     /// </summary>
     /// <param name="keyValues">The key values.</param>
     /// <returns>The associated property.</returns>
-    IProperty? FindNullPropertyInKeyValues(object?[] keyValues);
+    IProperty? FindNullPropertyInKeyValues(IReadOnlyList<object?> keyValues);
 
     /// <summary>
     ///     Creates a key object from the key values in the given entry.

src/EFCore/ChangeTracking/Internal/CompositeDependentKeyValueFactory.cs

@@ -12,7 +12,7 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
 public class CompositeDependentKeyValueFactory : CompositeValueFactory
 {
     private readonly IForeignKey _foreignKey;
-    private readonly IPrincipalKeyValueFactory<object[]> _principalKeyValueFactory;
+    private readonly IPrincipalKeyValueFactory<IReadOnlyList<object?>> _principalKeyValueFactory;
 
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -22,7 +22,7 @@ public class CompositeDependentKeyValueFactory : CompositeValueFactory
     /// </summary>
     public CompositeDependentKeyValueFactory(
         IForeignKey foreignKey,
-        IPrincipalKeyValueFactory<object[]> principalKeyValueFactory)
+        IPrincipalKeyValueFactory<IReadOnlyList<object?>> principalKeyValueFactory)
         : base(foreignKey.Properties)
     {
         _foreignKey = foreignKey;
@@ -36,7 +36,7 @@ public CompositeDependentKeyValueFactory(
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     public override object CreatePrincipalEquatableKey(IUpdateEntry entry, bool fromOriginalValues)
-        => new EquatableKeyValue<object[]>(
+        => new EquatableKeyValue<IReadOnlyList<object?>>(
             _foreignKey,
             fromOriginalValues
                 ? _principalKeyValueFactory.CreateFromOriginalValues(entry)!
@@ -52,9 +52,9 @@ public override object CreatePrincipalEquatableKey(IUpdateEntry entry, bool from
     public override object? CreateDependentEquatableKey(IUpdateEntry entry, bool fromOriginalValues)
         => fromOriginalValues
             ? TryCreateFromOriginalValues(entry, out var originalKeyValue)
-                ? new EquatableKeyValue<object[]>(_foreignKey, originalKeyValue, EqualityComparer)
+                ? new EquatableKeyValue<IReadOnlyList<object?>>(_foreignKey, originalKeyValue, EqualityComparer)
                 : null
             : TryCreateFromCurrentValues(entry, out var keyValue)
-                ? new EquatableKeyValue<object[]>(_foreignKey, keyValue, EqualityComparer)
+                ? new EquatableKeyValue<IReadOnlyList<object?>>(_foreignKey, keyValue, EqualityComparer)
                 : null;
 }

src/EFCore/ChangeTracking/Internal/CompositePrincipalKeyValueFactory.cs

@@ -9,7 +9,7 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
 ///     any release. You should only use it directly in your code with extreme caution and knowing that
 ///     doing so can result in application failures when updating to a new Entity Framework Core release.
 /// </summary>
-public class CompositePrincipalKeyValueFactory : CompositeValueFactory, IPrincipalKeyValueFactory<object[]>
+public class CompositePrincipalKeyValueFactory : CompositeValueFactory, IPrincipalKeyValueFactory<IReadOnlyList<object?>>
 {
     private readonly IKey _key;
 
@@ -31,8 +31,18 @@ public CompositePrincipalKeyValueFactory(IKey key)
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual object? CreateFromKeyValues(object?[] keyValues)
-        => keyValues.Any(v => v == null) ? null : keyValues;
+    public virtual object? CreateFromKeyValues(IReadOnlyList<object?> keyValues) // ReSharper disable once PossibleMultipleEnumeration
+    {
+        for (var i = 0; i < keyValues.Count; i++)
+        {
+            if (keyValues[i] == null)
+            {
+                return null;
+            }
+        }
+
+        return keyValues;
+    }
 
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -49,10 +59,10 @@ public CompositePrincipalKeyValueFactory(IKey key)
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual IProperty FindNullPropertyInKeyValues(object?[] keyValues)
+    public virtual IProperty FindNullPropertyInKeyValues(IReadOnlyList<object?> keyValues)
     {
         var index = -1;
-        for (var i = 0; i < keyValues.Length; i++)
+        for (var i = 0; i < keyValues.Count; i++)
         {
             if (keyValues[i] == null)
             {
@@ -70,7 +80,7 @@ public virtual IProperty FindNullPropertyInKeyValues(object?[] keyValues)
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual object[] CreateFromCurrentValues(IUpdateEntry entry)
+    public virtual IReadOnlyList<object?> CreateFromCurrentValues(IUpdateEntry entry)
         => CreateFromEntry(entry, (e, p) => e.GetCurrentValue(p));
 
     /// <summary>
@@ -88,7 +98,7 @@ public virtual object[] CreateFromCurrentValues(IUpdateEntry entry)
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual object[] CreateFromOriginalValues(IUpdateEntry entry)
+    public virtual IReadOnlyList<object?> CreateFromOriginalValues(IUpdateEntry entry)
         => CreateFromEntry(entry, (e, p) => e.GetOriginalValue(p));
 
     /// <summary>
@@ -97,25 +107,23 @@ public virtual object[] CreateFromOriginalValues(IUpdateEntry entry)
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual object[] CreateFromRelationshipSnapshot(IUpdateEntry entry)
+    public virtual IReadOnlyList<object?> CreateFromRelationshipSnapshot(IUpdateEntry entry)
         => CreateFromEntry(entry, (e, p) => e.GetRelationshipSnapshotValue(p));
 
     private object[] CreateFromEntry(
         IUpdateEntry entry,
         Func<IUpdateEntry, IProperty, object?> getValue)
     {
         var values = new object[Properties.Count];
-        var index = 0;
-
-        foreach (var property in Properties)
+        for (var i = 0; i < values.Length; i++)
         {
-            var value = getValue(entry, property);
+            var value = getValue(entry, Properties[i]);
             if (value == null)
             {
                 return default!;
             }
 
-            values[index++] = value;
+            values[i] = value;
         }
 
         return values;
@@ -128,7 +136,7 @@ private object[] CreateFromEntry(
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     public virtual object CreateEquatableKey(IUpdateEntry entry, bool fromOriginalValues)
-        => new EquatableKeyValue<object[]>(
+        => new EquatableKeyValue<IReadOnlyList<object?>>(
             _key,
             fromOriginalValues
                 ? CreateFromOriginalValues(entry)

src/EFCore/ChangeTracking/Internal/CompositeValueFactory.cs

@@ -11,7 +11,7 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
 ///     any release. You should only use it directly in your code with extreme caution and knowing that
 ///     doing so can result in application failures when updating to a new Entity Framework Core release.
 /// </summary>
-public class CompositeValueFactory : IDependentKeyValueFactory<object[]>
+public class CompositeValueFactory : IDependentKeyValueFactory<IReadOnlyList<object?>>
 {
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -31,7 +31,7 @@ public CompositeValueFactory(IReadOnlyList<IProperty> properties)
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual IEqualityComparer<object[]> EqualityComparer { get; }
+    public virtual IEqualityComparer<IReadOnlyList<object?>> EqualityComparer { get; }
 
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -47,23 +47,22 @@ public CompositeValueFactory(IReadOnlyList<IProperty> properties)
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual bool TryCreateFromBuffer(in ValueBuffer valueBuffer, [NotNullWhen(true)] out object[]? key)
+    public virtual bool TryCreateFromBuffer(in ValueBuffer valueBuffer, [NotNullWhen(true)] out IReadOnlyList<object?>? key)
     {
-        key = new object[Properties.Count];
-        var index = 0;
-
-        foreach (var property in Properties)
+        var keyArray = new object[Properties.Count];
+        for (var i = 0; i < keyArray.Length; i++)
         {
-            var value = valueBuffer[property.GetIndex()];
+            var value = valueBuffer[Properties[i].GetIndex()];
             if (value == null)
             {
                 key = null;
                 return false;
             }
 
-            key[index++] = value;
+            keyArray[i] = value;
         }
 
+        key = keyArray;
         return true;
     }
 
@@ -73,7 +72,7 @@ public virtual bool TryCreateFromBuffer(in ValueBuffer valueBuffer, [NotNullWhen
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual bool TryCreateFromCurrentValues(IUpdateEntry entry, [NotNullWhen(true)] out object[]? key)
+    public virtual bool TryCreateFromCurrentValues(IUpdateEntry entry, [NotNullWhen(true)] out IReadOnlyList<object?>? key)
         => TryCreateFromEntry(entry, (e, p) => e.GetCurrentValue(p), out key);
 
     /// <summary>
@@ -82,7 +81,7 @@ public virtual bool TryCreateFromCurrentValues(IUpdateEntry entry, [NotNullWhen(
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual bool TryCreateFromPreStoreGeneratedCurrentValues(IUpdateEntry entry, [NotNullWhen(true)] out object[]? key)
+    public virtual bool TryCreateFromPreStoreGeneratedCurrentValues(IUpdateEntry entry, [NotNullWhen(true)] out IReadOnlyList<object?>? key)
         => TryCreateFromEntry(entry, (e, p) => e.GetPreStoreGeneratedCurrentValue(p), out key);
 
     /// <summary>
@@ -91,7 +90,7 @@ public virtual bool TryCreateFromPreStoreGeneratedCurrentValues(IUpdateEntry ent
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual bool TryCreateFromOriginalValues(IUpdateEntry entry, [NotNullWhen(true)] out object[]? key)
+    public virtual bool TryCreateFromOriginalValues(IUpdateEntry entry, [NotNullWhen(true)] out IReadOnlyList<object?>? key)
         => TryCreateFromEntry(entry, (e, p) => e.GetOriginalValue(p), out key);
 
     /// <summary>
@@ -100,7 +99,7 @@ public virtual bool TryCreateFromOriginalValues(IUpdateEntry entry, [NotNullWhen
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual bool TryCreateFromRelationshipSnapshot(IUpdateEntry entry, [NotNullWhen(true)] out object[]? key)
+    public virtual bool TryCreateFromRelationshipSnapshot(IUpdateEntry entry, [NotNullWhen(true)] out IReadOnlyList<object?>? key)
         => TryCreateFromEntry(entry, (e, p) => e.GetRelationshipSnapshotValue(p), out key);
 
     /// <summary>
@@ -112,23 +111,22 @@ public virtual bool TryCreateFromRelationshipSnapshot(IUpdateEntry entry, [NotNu
     protected virtual bool TryCreateFromEntry(
         IUpdateEntry entry,
         Func<IUpdateEntry, IProperty, object?> getValue,
-        [NotNullWhen(true)] out object[]? key)
+        [NotNullWhen(true)] out IReadOnlyList<object?>? key)
     {
-        key = new object[Properties.Count];
-        var index = 0;
-
-        foreach (var property in Properties)
+        var keyArray = new object[Properties.Count];
+        for (var i = 0; i < keyArray.Length; i++)
         {
-            var value = getValue(entry, property);
+            var value = getValue(entry, Properties[i]);
             if (value == null)
             {
                 key = null;
                 return false;
             }
 
-            key[index++] = value;
+            keyArray[i] = value;
         }
 
+        key = keyArray;
         return true;
     }
 
@@ -156,21 +154,23 @@ public virtual object CreatePrincipalEquatableKey(IUpdateEntry entry, bool fromO
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    protected static IEqualityComparer<object[]> CreateEqualityComparer(IReadOnlyList<IProperty> properties)
+    protected static IEqualityComparer<IReadOnlyList<object?>> CreateEqualityComparer(IReadOnlyList<IProperty> properties)
         => new CompositeCustomComparer(properties.Select(p => p.GetKeyValueComparer()).ToList());
 
-    private sealed class CompositeCustomComparer : IEqualityComparer<object[]>
+    private sealed class CompositeCustomComparer : IEqualityComparer<IReadOnlyList<object?>>
     {
-        private readonly Func<object, object, bool>[] _equals;
-        private readonly Func<object, int>[] _hashCodes;
+        private readonly int _valueCount;
+        private readonly Func<object?, object?, bool>[] _equals;
+        private readonly Func<object?, int>[] _hashCodes;
 
         public CompositeCustomComparer(IList<ValueComparer> comparers)
         {
-            _equals = comparers.Select(c => (Func<object, object, bool>)c.Equals).ToArray();
-            _hashCodes = comparers.Select(c => (Func<object, int>)c.GetHashCode).ToArray();
+            _valueCount = comparers.Count;
+            _equals = comparers.Select(c => (Func<object?, object?, bool>)c.Equals).ToArray();
+            _hashCodes = comparers.Select(c => (Func<object?, int>)c.GetHashCode).ToArray();
         }
 
-        public bool Equals(object[]? x, object[]? y)
+        public bool Equals(IReadOnlyList<object?>? x, IReadOnlyList<object?>? y)
         {
             if (ReferenceEquals(x, y))
             {
@@ -187,12 +187,13 @@ public bool Equals(object[]? x, object[]? y)
                 return false;
             }
 
-            if (x.Length != y.Length)
+            if (x.Count != _valueCount
+                || y.Count != _valueCount)
             {
                 return false;
             }
 
-            for (var i = 0; i < x.Length; i++)
+            for (var i = 0; i < _valueCount; i++)
             {
                 if (!_equals[i](x[i], y[i]))
                 {
@@ -203,13 +204,13 @@ public bool Equals(object[]? x, object[]? y)
             return true;
         }
 
-        public int GetHashCode(object[] obj)
+        public int GetHashCode(IReadOnlyList<object?> obj)
         {
             var hashCode = new HashCode();
 
             // ReSharper disable once ForCanBeConvertedToForeach
             // ReSharper disable once LoopCanBeConvertedToQuery
-            for (var i = 0; i < obj.Length; i++)
+            for (var i = 0; i < obj.Count; i++)
             {
                 hashCode.Add(_hashCodes[i](obj[i]));
             }

src/EFCore/ChangeTracking/Internal/DependentKeyValueFactory.cs

@@ -23,7 +23,7 @@ public abstract class DependentKeyValueFactory<TKey>
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public DependentKeyValueFactory(
+    protected DependentKeyValueFactory(
         IForeignKey foreignKey,
         IPrincipalKeyValueFactory<TKey> principalKeyValueFactory)
     {

src/EFCore/ChangeTracking/Internal/DependentKeyValueFactoryFactory.cs

@@ -47,8 +47,8 @@ public virtual IDependentKeyValueFactory<TKey> CreateSimple<TKey>(
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual IDependentKeyValueFactory<object[]> CreateComposite(
+    public virtual IDependentKeyValueFactory<IReadOnlyList<object?>> CreateComposite(
         IForeignKey foreignKey,
-        IPrincipalKeyValueFactory<object[]> principalKeyValueFactory)
+        IPrincipalKeyValueFactory<IReadOnlyList<object?>> principalKeyValueFactory)
         => new CompositeDependentKeyValueFactory(foreignKey, principalKeyValueFactory);
 }

src/EFCore/ChangeTracking/Internal/DependentsMap.cs

@@ -130,6 +130,17 @@ public virtual IEnumerable<IUpdateEntry> GetDependents(IUpdateEntry principalEnt
             ? dependents
             : Enumerable.Empty<IUpdateEntry>();
 
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual IEnumerable<IUpdateEntry> GetDependents(IReadOnlyList<object?> keyValues)
+        => _map.TryGetValue((TKey)_principalKeyValueFactory.CreateFromKeyValues(keyValues)!, out var dependents)
+            ? dependents
+            : Enumerable.Empty<IUpdateEntry>();
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in