Separate element type from primitive collection

src/EFCore/Metadata/Builders/IConventionPropertyBuilder.cs

@@ -545,13 +545,13 @@ bool CanSetProviderValueComparer(
     ///     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>
-    IConventionElementTypeBuilder? SetElementType(bool elementType, bool fromDataAnnotation = false);
+    IConventionElementTypeBuilder? SetElementType(Type? elementType, bool fromDataAnnotation = false);
 
     /// <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>
-    bool CanSetElementType(bool elementType, bool fromDataAnnotation = false);
+    bool CanSetElementType(Type? elementType, bool fromDataAnnotation = false);
 }

src/EFCore/Metadata/Conventions/PropertyDiscoveryConvention.cs

@@ -94,7 +94,11 @@ private void Process(IConventionEntityTypeBuilder entityTypeBuilder)
             var propertyBuilder = entityTypeBuilder.Property(propertyInfo);
             if (mapping?.ElementTypeMapping != null)
             {
-                propertyBuilder?.SetElementType(true);
+                var elementType = propertyInfo.PropertyType.TryGetElementType(typeof(IEnumerable<>));
+                if (elementType != null)
+                {
+                    propertyBuilder?.SetElementType(elementType);
+                }
             }
         }
     }

src/EFCore/Metadata/IConventionProperty.cs

@@ -472,7 +472,7 @@ bool IsImplicitlyCreated()
     /// <param name="elementType">If <see langword="true"/>, then the type mapping has an element type, otherwise it is removed.</param>
     /// <param name="fromDataAnnotation">Indicates whether the configuration was specified using a data annotation.</param>
     /// <returns>The configuration for the elements.</returns>
-    IConventionElementType? SetElementType(bool elementType, bool fromDataAnnotation = false);
+    IConventionElementType? SetElementType(Type? elementType, bool fromDataAnnotation = false);
 
     /// <summary>
     ///     Returns the configuration source for <see cref="IReadOnlyProperty.GetElementType" />.

src/EFCore/Metadata/IMutableProperty.cs

@@ -283,7 +283,7 @@ void SetProviderValueComparer(
     ///     Sets the configuration for elements of the primitive collection represented by this property.
     /// </summary>
     /// <param name="elementType">If <see langword="true"/>, then this is a collection of primitive elements.</param>
-    void SetElementType(bool elementType);
+    void SetElementType(Type? elementType);
 
     /// <inheritdoc />
     bool IReadOnlyProperty.IsNullable

src/EFCore/Metadata/IReadOnlyProperty.cs

@@ -179,6 +179,12 @@ CoreTypeMapping GetTypeMapping()
     /// <returns>The configuration for the elements.</returns>
     IReadOnlyElementType? GetElementType();
 
+    /// <summary>
+    ///     A property is a primitive collection if it has an element type that matches the element type of the CLR type.
+    /// </summary>
+    /// <returns><see langword="true"/> if the property represents a primitive collection.</returns>
+    bool IsPrimitiveCollection { get; }
+
     /// <summary>
     ///     Finds the first principal property that the given property is constrained by
     ///     if the given property is part of a foreign key.

src/EFCore/Metadata/Internal/InternalPropertyBuilder.cs

@@ -564,7 +564,7 @@ public virtual bool CanSetConversion(Type? providerClrType, ConfigurationSource?
     {
         if (CanSetConverter(converterType, configurationSource))
         {
-            Metadata.SetElementType(false, configurationSource);
+            Metadata.SetElementType(null, configurationSource);
             Metadata.SetProviderClrType(null, configurationSource);
             Metadata.SetValueConverter(converterType, configurationSource);
 
@@ -776,13 +776,13 @@ public virtual bool CanSetProviderValueComparer(
     ///     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 InternalElementTypeBuilder? SetElementType(bool elementType, ConfigurationSource configurationSource)
+    public virtual InternalElementTypeBuilder? SetElementType(Type? elementType, ConfigurationSource configurationSource)
     {
         if (CanSetElementType(elementType, configurationSource))
         {
             Metadata.SetElementType(elementType, configurationSource);
             Metadata.SetValueConverter((Type?)null, configurationSource);
-            return new InternalElementTypeBuilder((ElementType)Metadata.GetElementType()!, ModelBuilder);
+            return new InternalElementTypeBuilder(Metadata.GetElementType()!, ModelBuilder);
         }
 
         return null;
@@ -794,9 +794,9 @@ public virtual bool CanSetProviderValueComparer(
     ///     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 CanSetElementType(bool elementType, ConfigurationSource? configurationSource)
+    public virtual bool CanSetElementType(Type? elementType, ConfigurationSource? configurationSource)
         => configurationSource.Overrides(Metadata.GetElementTypeConfigurationSource())
-            && (elementType != (Metadata.GetElementType() != null));
+            && (elementType != Metadata.GetElementType()?.ClrType);
 
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -1523,7 +1523,7 @@ bool IConventionPropertyBuilder.CanSetProviderValueComparer(
     ///     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>
-    IConventionElementTypeBuilder? IConventionPropertyBuilder.SetElementType(bool elementType, bool fromDataAnnotation)
+    IConventionElementTypeBuilder? IConventionPropertyBuilder.SetElementType(Type? elementType, bool fromDataAnnotation)
         => SetElementType(elementType, fromDataAnnotation ? ConfigurationSource.DataAnnotation : ConfigurationSource.Convention);
 
     /// <summary>
@@ -1532,6 +1532,6 @@ bool IConventionPropertyBuilder.CanSetProviderValueComparer(
     ///     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>
-    bool IConventionPropertyBuilder.CanSetElementType(bool elementType, bool fromDataAnnotation)
+    bool IConventionPropertyBuilder.CanSetElementType(Type? elementType, bool fromDataAnnotation)
         => CanSetElementType(elementType, fromDataAnnotation ? ConfigurationSource.DataAnnotation : ConfigurationSource.Convention);
 }

src/EFCore/Metadata/Internal/InternalTypeBaseBuilder.cs

@@ -333,7 +333,16 @@ public static bool IsCompatible(MemberInfo? newMemberInfo, PropertyBase existing
     {
         var builder = Property(propertyType, propertyName, memberInfo, typeConfigurationSource, configurationSource);
 
-        builder?.SetElementType(true, configurationSource!.Value);
+        if (builder != null)
+        {
+            var elementClrType = builder.Metadata.ClrType.TryGetElementType(typeof(IEnumerable<>));
+            if (elementClrType == null)
+            {
+                throw new InvalidOperationException(CoreStrings.NotCollection(builder.Metadata.ClrType.ShortDisplayName(), propertyName));
+            }
+
+            builder.SetElementType(elementClrType, configurationSource!.Value);
+        }
 
         return builder;
     }

src/EFCore/Metadata/Internal/Property.cs

@@ -1208,32 +1208,44 @@ public virtual CoreTypeMapping? TypeMapping
     public virtual ElementType? GetElementType()
         => (ElementType?)this[CoreAnnotationNames.ElementType];
 
+    /// <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 bool IsPrimitiveCollection
+    {
+        get
+        {
+            var elementType = GetElementType();
+            return elementType != null
+                && ClrType.TryGetElementType(typeof(IEnumerable<>))?.IsAssignableFrom(elementType!.ClrType) == true;
+        }
+    }
+
     /// <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 ElementType? SetElementType(
-        bool elementType,
+        Type? elementType,
         ConfigurationSource configurationSource)
     {
         var existingElementType = GetElementType();
-        if (existingElementType == null
-            && elementType)
+        if (elementType != null
+            && elementType != existingElementType?.ClrType)
         {
-            var elementClrType = ClrType.TryGetElementType(typeof(IEnumerable<>));
-            if (elementClrType == null)
-            {
-                throw new InvalidOperationException(CoreStrings.NotCollection(ClrType.ShortDisplayName(), Name));
-            }
-            var newElementType = new ElementType(elementClrType, this, configurationSource);
+            var newElementType = new ElementType(elementType, this, configurationSource);
             SetAnnotation(CoreAnnotationNames.ElementType, newElementType, configurationSource);
             OnElementTypeSet(newElementType, null);
             return newElementType;
         }
 
-        if (existingElementType != null && !elementType)
+        if (elementType == null
+            && existingElementType != null)
         {
             existingElementType.SetRemovedFromModel();
             RemoveAnnotation(CoreAnnotationNames.ElementType);
@@ -2017,7 +2029,7 @@ void IMutableProperty.SetJsonValueReaderWriterType(Type? readerWriterType)
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     [DebuggerStepThrough]
-    IConventionElementType? IConventionProperty.SetElementType(bool elementType, bool fromDataAnnotation)
+    IConventionElementType? IConventionProperty.SetElementType(Type? elementType, bool fromDataAnnotation)
         => SetElementType(
             elementType,
             fromDataAnnotation ? ConfigurationSource.DataAnnotation : ConfigurationSource.Convention);
@@ -2029,7 +2041,7 @@ void IMutableProperty.SetJsonValueReaderWriterType(Type? readerWriterType)
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     [DebuggerStepThrough]
-    void IMutableProperty.SetElementType(bool elementType)
+    void IMutableProperty.SetElementType(Type? elementType)
         => SetElementType(elementType, ConfigurationSource.Explicit);
 
     /// <summary>

src/EFCore/Metadata/RuntimeProperty.cs

@@ -155,6 +155,8 @@ public virtual RuntimeElementType SetElementType(
 
         SetAnnotation(CoreAnnotationNames.ElementType, elementType);
 
+        IsPrimitiveCollection = ClrType.TryGetElementType(typeof(IEnumerable<>))?.IsAssignableFrom(clrType) == true;
+
         return elementType;
     }
 
@@ -305,6 +307,14 @@ public override object? Sentinel
     public virtual IElementType? GetElementType()
         => (IElementType?)this[CoreAnnotationNames.ElementType];
 
+    /// <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 bool IsPrimitiveCollection { get; private set; }
+
     /// <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

test/EFCore.Tests/Metadata/Conventions/ConventionDispatcherTest.cs

@@ -3689,12 +3689,12 @@ public void OnPropertyElementTypeChanged_calls_conventions_in_order(bool useBuil
 
         if (useBuilder)
         {
-            Assert.NotNull(propertyBuilder.SetElementType(true, ConfigurationSource.Convention));
-            elementType = (ElementType)propertyBuilder.Metadata.GetElementType()!;
+            Assert.NotNull(propertyBuilder.SetElementType(typeof(int), ConfigurationSource.Convention));
+            elementType = propertyBuilder.Metadata.GetElementType()!;
         }
         else
         {
-            elementType = (ElementType)propertyBuilder.Metadata.SetElementType(true, ConfigurationSource.Convention);
+            elementType = propertyBuilder.Metadata.SetElementType(typeof(int), ConfigurationSource.Convention);
         }
 
         if (useScope)
@@ -3710,12 +3710,12 @@ public void OnPropertyElementTypeChanged_calls_conventions_in_order(bool useBuil
 
         if (useBuilder)
         {
-            Assert.Null(propertyBuilder.SetElementType(true, ConfigurationSource.Convention));
-            elementType = (ElementType)propertyBuilder.Metadata.GetElementType()!;
+            Assert.Null(propertyBuilder.SetElementType(typeof(int), ConfigurationSource.Convention));
+            elementType = propertyBuilder.Metadata.GetElementType()!;
         }
         else
         {
-            elementType = (ElementType)propertyBuilder.Metadata.SetElementType(true, ConfigurationSource.Convention);
+            elementType = propertyBuilder.Metadata.SetElementType(typeof(int), ConfigurationSource.Convention);
         }
 
         Assert.Equal(new (object, object)[] { (null, elementType) }, convention1.Calls);
@@ -3724,11 +3724,11 @@ public void OnPropertyElementTypeChanged_calls_conventions_in_order(bool useBuil
 
         if (useBuilder)
         {
-            Assert.NotNull(propertyBuilder.SetElementType(false, ConfigurationSource.Convention));
+            Assert.NotNull(propertyBuilder.SetElementType(null, ConfigurationSource.Convention));
         }
         else
         {
-            Assert.Null(propertyBuilder.Metadata.SetElementType(false, ConfigurationSource.Convention));
+            Assert.Null(propertyBuilder.Metadata.SetElementType(null, ConfigurationSource.Convention));
         }
 
         Assert.Equal(new (object, object)[] { (null, elementType), (elementType, null) }, convention1.Calls);
@@ -5069,7 +5069,7 @@ public void OnElementTypeAnnotationChanged_calls_conventions_in_order(bool useBu
         var builder = new InternalModelBuilder(new Model(conventions));
         var elementTypeBuilder = builder.Entity(typeof(SpecialOrder), ConfigurationSource.Convention)!
             .Property(nameof(SpecialOrder.OrderIds), ConfigurationSource.Convention)!
-            .SetElementType(true, ConfigurationSource.Convention)!;
+            .SetElementType(typeof(int), ConfigurationSource.Convention)!;
 
         var scope = useScope ? builder.Metadata.ConventionDispatcher.DelayConventions() : null;
 
@@ -5174,7 +5174,7 @@ public void OnElementTypeNullabilityChanged_calls_conventions_in_order(bool useB
         var builder = new InternalModelBuilder(model);
         var elementTypeBuilder = builder.Entity(typeof(SpecialOrder), ConfigurationSource.Convention)!
             .Property(nameof(SpecialOrder.Notes), ConfigurationSource.Convention)!
-            .SetElementType(true, ConfigurationSource.Convention)!;
+            .SetElementType(typeof(string), ConfigurationSource.Convention)!;
 
         if (useBuilder)
         {

test/EFCore.Tests/Metadata/Internal/ClrPropertyGetterFactoryTest.cs

@@ -91,6 +91,8 @@ public JsonValueReaderWriter GetJsonValueReaderWriter()
         IReadOnlyElementType IReadOnlyProperty.GetElementType()
             => GetElementType();
 
+        public bool IsPrimitiveCollection { get; }
+
         public IElementType GetElementType()
             => throw new NotImplementedException();
 

test/EFCore.Tests/Metadata/Internal/ClrPropertySetterFactoryTest.cs

@@ -103,6 +103,8 @@ public JsonValueReaderWriter GetJsonValueReaderWriter()
         IReadOnlyElementType IReadOnlyProperty.GetElementType()
             => GetElementType();
 
+        public bool IsPrimitiveCollection { get; }
+
         public IElementType GetElementType()
             => throw new NotImplementedException();
 

test/EFCore.Tests/Metadata/Internal/PropertyTest.cs

@@ -531,6 +531,42 @@ public void Throws_when_JsonValueReaderWriter_instance_cannot_be_created(Type ty
                 () => property.GetJsonValueReaderWriter()).Message);
     }
 
+    [ConditionalFact]
+    public void Can_set_element_type_for_primitive_collection()
+    {
+        var model = CreateModel();
+        var entityType = model.AddEntityType(typeof(object));
+        var property = entityType.AddProperty("Random", typeof(IList<int>));
+        property.SetElementType(typeof(int));
+
+        Assert.Equal(typeof(int), property.GetElementType()!.ClrType);
+        Assert.True(property.IsPrimitiveCollection);
+    }
+
+    [ConditionalFact]
+    public void Can_set_derived_element_type_for_primitive_collection()
+    {
+        var model = CreateModel();
+        var entityType = model.AddEntityType(typeof(object));
+        var property = entityType.AddProperty("Random", typeof(IList<object>));
+        property.SetElementType(typeof(int));
+
+        Assert.Equal(typeof(int), property.GetElementType()!.ClrType);
+        Assert.True(property.IsPrimitiveCollection);
+    }
+
+    [ConditionalFact]
+    public void Can_set_element_type_for_non_primitive_collection()
+    {
+        var model = CreateModel();
+        var entityType = model.AddEntityType(typeof(object));
+        var property = entityType.AddProperty("Random", typeof(Random));
+        property.SetElementType(typeof(int));
+
+        Assert.Equal(typeof(int), property.GetElementType()!.ClrType);
+        Assert.False(property.IsPrimitiveCollection);
+    }
+
     private class SimpleJasonValueReaderWriter : JsonValueReaderWriter<string>
     {
         public override string FromJsonTyped(ref Utf8JsonReaderManager manager, object existingObject = null)