Allow ignoring non-virtual navigations with lazy-loading proxies

Part of #10787

Like the EF6 behavior, but opt-in.

src/EFCore.Proxies/Proxies/Internal/ProxiesOptionsExtension.cs

@@ -16,6 +16,7 @@ public class ProxiesOptionsExtension : IDbContextOptionsExtension
 {
     private DbContextOptionsExtensionInfo? _info;
     private bool _useLazyLoadingProxies;
+    private bool _ignoreNonVirtualNavigations;
     private bool _useChangeTrackingProxies;
     private bool _checkEquality;
 
@@ -38,6 +39,7 @@ public ProxiesOptionsExtension()
     protected ProxiesOptionsExtension(ProxiesOptionsExtension copyFrom)
     {
         _useLazyLoadingProxies = copyFrom._useLazyLoadingProxies;
+        _ignoreNonVirtualNavigations = copyFrom._ignoreNonVirtualNavigations;
         _useChangeTrackingProxies = copyFrom._useChangeTrackingProxies;
         _checkEquality = copyFrom._checkEquality;
     }
@@ -69,6 +71,15 @@ protected virtual ProxiesOptionsExtension Clone()
     public virtual bool UseLazyLoadingProxies
         => _useLazyLoadingProxies;
 
+    /// <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 IgnoreNonVirtualNavigations
+        => _ignoreNonVirtualNavigations;
+
     /// <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
@@ -102,11 +113,12 @@ public virtual bool UseProxies
     ///     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 ProxiesOptionsExtension WithLazyLoading(bool useLazyLoadingProxies = true)
+    public virtual ProxiesOptionsExtension WithLazyLoading(bool useLazyLoadingProxies, bool ignoreNonVirtualNavigations)
     {
         var clone = Clone();
 
         clone._useLazyLoadingProxies = useLazyLoadingProxies;
+        clone._ignoreNonVirtualNavigations = ignoreNonVirtualNavigations;
 
         return clone;
     }
@@ -117,7 +129,7 @@ public virtual ProxiesOptionsExtension WithLazyLoading(bool useLazyLoadingProxie
     ///     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 ProxiesOptionsExtension WithChangeTracking(bool useChangeTrackingProxies = true, bool checkEquality = true)
+    public virtual ProxiesOptionsExtension WithChangeTracking(bool useChangeTrackingProxies, bool checkEquality)
     {
         var clone = Clone();
 
@@ -187,6 +199,7 @@ public override int GetServiceProviderHashCode()
         {
             var hashCode = new HashCode();
             hashCode.Add(Extension.UseLazyLoadingProxies);
+            hashCode.Add(Extension.IgnoreNonVirtualNavigations);
             hashCode.Add(Extension.UseChangeTrackingProxies);
             hashCode.Add(Extension.CheckEquality);
             return hashCode.ToHashCode();
@@ -195,6 +208,7 @@ public override int GetServiceProviderHashCode()
         public override bool ShouldUseSameServiceProvider(DbContextOptionsExtensionInfo other)
             => other is ExtensionInfo otherInfo
                 && Extension.UseLazyLoadingProxies == otherInfo.Extension.UseLazyLoadingProxies
+                && Extension.IgnoreNonVirtualNavigations == otherInfo.Extension.IgnoreNonVirtualNavigations
                 && Extension.UseChangeTrackingProxies == otherInfo.Extension.UseChangeTrackingProxies
                 && Extension.CheckEquality == otherInfo.Extension.CheckEquality;
 

src/EFCore.Proxies/Proxies/Internal/ProxyBindingRewriter.cs

@@ -94,15 +94,20 @@ public virtual void ProcessModelFinalizing(
 
                         if (_options.UseLazyLoadingProxies)
                         {
-                            if (!navigationBase.PropertyInfo.GetMethod!.IsReallyVirtual()
-                                && (!(navigationBase is INavigation navigation
-                                    && navigation.ForeignKey.IsOwnership)))
+                            if (!navigationBase.PropertyInfo.GetMethod!.IsReallyVirtual())
                             {
-                                throw new InvalidOperationException(
-                                    ProxiesStrings.NonVirtualProperty(navigationBase.Name, entityType.DisplayName()));
+                                if (!_options.IgnoreNonVirtualNavigations
+                                    && !(navigationBase is INavigation navigation
+                                        && navigation.ForeignKey.IsOwnership))
+                                {
+                                    throw new InvalidOperationException(
+                                        ProxiesStrings.NonVirtualProperty(navigationBase.Name, entityType.DisplayName()));
+                                }
+                            }
+                            else
+                            {
+                                navigationBase.SetPropertyAccessMode(PropertyAccessMode.Field);
                             }
-
-                            navigationBase.SetPropertyAccessMode(PropertyAccessMode.Field);
                         }
                     }
                 }

src/EFCore.Proxies/ProxiesExtensions.cs

@@ -105,15 +105,20 @@ public static DbContextOptionsBuilder<TContext> UseChangeTrackingProxies<TContex
     ///     or exposed AddDbContext.
     /// </param>
     /// <param name="useLazyLoadingProxies"><see langword="true" /> to use lazy loading proxies; <see langword="false" /> to prevent their use.</param>
+    /// <param name="ignoreNonVirtualNavigations">
+    ///     <see langword="true" /> to ignore navigations that are not virtual. The default value is
+    ///     <see langword="false" />, meaning an exception will be thrown if a non-virtual navigation is found.
+    /// </param>
     /// <returns>The same builder to allow method calls to be chained.</returns>
     public static DbContextOptionsBuilder UseLazyLoadingProxies(
         this DbContextOptionsBuilder optionsBuilder,
-        bool useLazyLoadingProxies = true)
+        bool useLazyLoadingProxies = true,
+        bool ignoreNonVirtualNavigations = false)
     {
         var extension = optionsBuilder.Options.FindExtension<ProxiesOptionsExtension>()
             ?? new ProxiesOptionsExtension();
 
-        extension = extension.WithLazyLoading(useLazyLoadingProxies);
+        extension = extension.WithLazyLoading(useLazyLoadingProxies, ignoreNonVirtualNavigations);
 
         ((IDbContextOptionsBuilderInfrastructure)optionsBuilder).AddOrUpdateExtension(extension);
 
@@ -139,10 +144,15 @@ public static DbContextOptionsBuilder UseLazyLoadingProxies(
     ///     or exposed AddDbContext.
     /// </param>
     /// <param name="useLazyLoadingProxies"><see langword="true" /> to use lazy loading proxies; <see langword="false" /> to prevent their use.</param>
+    /// <param name="ignoreNonVirtualNavigations">
+    ///     <see langword="true" /> to ignore navigations that are not virtual. The default value is
+    ///     <see langword="false" />, meaning an exception will be thrown if a non-virtual navigation is found.
+    /// </param>
     /// <returns>The same builder to allow method calls to be chained.</returns>
     public static DbContextOptionsBuilder<TContext> UseLazyLoadingProxies<TContext>(
         this DbContextOptionsBuilder<TContext> optionsBuilder,
-        bool useLazyLoadingProxies = true)
+        bool useLazyLoadingProxies = true,
+        bool ignoreNonVirtualNavigations = false)
         where TContext : DbContext
         => (DbContextOptionsBuilder<TContext>)UseLazyLoadingProxies((DbContextOptionsBuilder)optionsBuilder, useLazyLoadingProxies);
 

test/EFCore.Proxies.Tests/LazyLoadingProxyTests.cs

@@ -28,6 +28,14 @@ public void Throws_if_non_virtual_navigation_to_non_owned_type()
                 () => context.Model).Message);
     }
 
+    [ConditionalFact]
+    public void Does_not_throw_if_non_virtual_navigation_to_non_owned_type_is_allowed()
+    {
+        using var context = new LazyContextIgnoreVirtuals<LazyNonVirtualNavEntity>();
+        Assert.NotNull(
+            context.Model.FindEntityType(typeof(LazyNonVirtualNavEntity))!.FindNavigation(nameof(LazyNonVirtualNavEntity.SelfRef)));
+    }
+
     [ConditionalFact]
     public void Does_not_throw_if_non_virtual_navigation_to_owned_type()
     {
@@ -82,6 +90,15 @@ public void Throws_when_context_is_disposed()
                 () => phone.Texts).Message);
     }
 
+    private class LazyContextIgnoreVirtuals<TEntity> : TestContext<TEntity>
+        where TEntity : class
+    {
+        public LazyContextIgnoreVirtuals()
+            : base(dbName: "LazyLoadingContext", useLazyLoading: true, useChangeDetection: false, ignoreNonVirtualNavigations: true)
+        {
+        }
+    }
+
     private class LazyContext<TEntity> : TestContext<TEntity>
         where TEntity : class
     {

test/EFCore.Proxies.Tests/TestUtilities/TestContext.cs

@@ -11,6 +11,7 @@ internal abstract class TestContext<TEntity> : DbContext
     private readonly IServiceProvider _internalServiceProvider;
     private readonly string _dbName;
     private readonly bool _useLazyLoadingProxies;
+    private readonly bool _ignoreNonVirtualNavigations;
     private readonly bool _useChangeDetectionProxies;
     private readonly bool _checkEquality;
     private readonly ChangeTrackingStrategy? _changeTrackingStrategy;
@@ -20,7 +21,8 @@ protected TestContext(
         bool useLazyLoading = false,
         bool useChangeDetection = false,
         bool checkEquality = true,
-        ChangeTrackingStrategy? changeTrackingStrategy = null)
+        ChangeTrackingStrategy? changeTrackingStrategy = null,
+        bool ignoreNonVirtualNavigations = false)
     {
         _internalServiceProvider
             = new ServiceCollection()
@@ -33,13 +35,14 @@ protected TestContext(
         _useChangeDetectionProxies = useChangeDetection;
         _checkEquality = checkEquality;
         _changeTrackingStrategy = changeTrackingStrategy;
+        _ignoreNonVirtualNavigations = ignoreNonVirtualNavigations;
     }
 
     protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
     {
         if (_useLazyLoadingProxies)
         {
-            optionsBuilder.UseLazyLoadingProxies();
+            optionsBuilder.UseLazyLoadingProxies(ignoreNonVirtualNavigations: _ignoreNonVirtualNavigations);
         }
 
         if (_useChangeDetectionProxies)

test/EFCore.Specification.Tests/LazyLoadProxyTestBase.cs

@@ -891,6 +891,74 @@ public virtual void Setting_reference_to_owned_type_to_null_is_allowed_on_virtua
         Assert.Null(owner.Address);
     }
 
+    [ConditionalFact]
+    public virtual void Non_virtual_one_to_one_reference_to_principal_is_not_lazy_loaded()
+    {
+        using var context = CreateContext(lazyLoadingEnabled: true);
+
+        var child = context.Set<NonVirtualChild>().Single(e => e.SingleParent != null);
+
+        Assert.Null(child.SingleParent);
+        context.Entry(child).Reference(e => e.SingleParent).Load();
+        Assert.NotNull(child.SingleParent);
+
+        child.SingleParent = null;
+        Assert.Null(child.SingleParent);
+        context.ChangeTracker.DetectChanges();
+        Assert.Null(child.SingleParent);
+    }
+
+    [ConditionalFact]
+    public virtual void Non_virtual_one_to_many_reference_to_principal_is_not_lazy_loaded()
+    {
+        using var context = CreateContext(lazyLoadingEnabled: true);
+
+        var child = context.Set<NonVirtualChild>().Single(e => e.CollectionParent != null);
+
+        Assert.Null(child.CollectionParent);
+        context.Entry(child).Reference(e => e.CollectionParent).Load();
+        Assert.NotNull(child.CollectionParent);
+
+        child.CollectionParent = null;
+        Assert.Null(child.CollectionParent);
+        context.ChangeTracker.DetectChanges();
+        Assert.Null(child.CollectionParent);
+    }
+
+    [ConditionalFact]
+    public virtual void Non_virtual_reference_to_dependent_is_not_lazy_loaded()
+    {
+        using var context = CreateContext(lazyLoadingEnabled: true);
+
+        var parent = context.Set<NonVirtualParent>().Single();
+
+        Assert.Null(parent.Child);
+        context.Entry(parent).Reference(e => e.Child).Load();
+        Assert.NotNull(parent.Child);
+
+        parent.Child = null;
+        Assert.Null(parent.Child);
+        context.ChangeTracker.DetectChanges();
+        Assert.Null(parent.Child);
+    }
+
+    [ConditionalFact]
+    public virtual void Non_virtual_collection_is_not_lazy_loaded()
+    {
+        using var context = CreateContext(lazyLoadingEnabled: true);
+
+        var parent = context.Set<NonVirtualParent>().Single();
+
+        Assert.Null(parent.Children);
+        context.Entry(parent).Collection(e => e.Children).Load();
+        Assert.Single(parent.Children!);
+
+        parent.Children.Clear();
+        Assert.Empty(parent.Children);
+        context.ChangeTracker.DetectChanges();
+        Assert.Empty(parent.Children);
+    }
+
     [ConditionalTheory]
     [InlineData(EntityState.Unchanged)]
     [InlineData(EntityState.Added)]
@@ -3317,6 +3385,24 @@ public class Quest : Tribe
         public virtual Called Called { set; get; }
     }
 
+    public class NonVirtualParent
+    {
+        [DatabaseGenerated(DatabaseGeneratedOption.None)]
+        public int Id { get; set; }
+
+        public NonVirtualChild Child { get; set; }
+        public List<NonVirtualChild> Children { get; set; }
+    }
+
+    public class NonVirtualChild
+    {
+        [DatabaseGenerated(DatabaseGeneratedOption.None)]
+        public int Id { get; set; }
+
+        public NonVirtualParent SingleParent { get; set; }
+        public NonVirtualParent CollectionParent { get; set; }
+    }
+
     public class NonVirtualOneToOneOwner
     {
         [DatabaseGenerated(DatabaseGeneratedOption.None)]
@@ -3444,7 +3530,7 @@ protected override string StoreName
             => "LazyLoadProxyTest";
 
         public override DbContextOptionsBuilder AddOptions(DbContextOptionsBuilder builder)
-            => base.AddOptions(builder.UseLazyLoadingProxies());
+            => base.AddOptions(builder.UseLazyLoadingProxies(ignoreNonVirtualNavigations: true));
 
         protected override IServiceCollection AddServices(IServiceCollection serviceCollection)
             => base.AddServices(
@@ -3618,6 +3704,13 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
                 .OwnsMany(o => o.Addresses, a => a.HasKey("Id"));
             modelBuilder.Entity<ExplicitLazyLoadVirtualOneToManyOwner>()
                 .OwnsMany(o => o.Addresses, a => a.HasKey("Id"));
+
+            modelBuilder.Entity<NonVirtualParent>(
+                b =>
+                {
+                    b.HasOne(e => e.Child).WithOne(e => e.SingleParent).HasPrincipalKey<NonVirtualChild>();
+                    b.HasMany(e => e.Children).WithOne(e => e.CollectionParent);
+                });
         }
 
         protected override void Seed(DbContext context)
@@ -3736,6 +3829,14 @@ protected override void Seed(DbContext context)
                     Id = 600, Addresses = new List<OwnedAddress> { new() { Street = "12 Grimmauld Place", PostalCode = "L0N D0N" } }
                 });
 
+            context.Add(
+                new NonVirtualParent
+                {
+                    Id = 100,
+                    Child = new() { Id = 100 },
+                    Children = new() { new() { Id = 101 } }
+                });
+
             context.SaveChanges();
         }
     }