[release/10.0] Fix owned entities with default values not saved in TPH with shared columns

src/EFCore.Relational/Update/ModificationCommand.cs

@@ -40,6 +40,9 @@ public class ModificationCommand : IModificationCommand, INonTrackedModification
     private static readonly bool UseOldBehavior37373 =
         AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue37373", out var enabled) && enabled;
 
+    private static readonly bool UseOldBehavior37525 =
+        AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue37525", out var enabled37525) && enabled37525;
+
     /// <summary>
     ///     Initializes a new <see cref="ModificationCommand" /> instance.
     /// </summary>
@@ -1256,7 +1259,11 @@ public bool TryPropagate(IColumnMappingBase mapping, IUpdateEntry entry)
                         && ((!_originalValueInitialized
                                 && property.GetValueComparer().Equals(
                                     Update.ColumnModification.GetCurrentValue(entry, property),
-                                    property.Sentinel))
+                                    property.Sentinel)
+                                && (UseOldBehavior37525
+                                    || !mapping.Column.ProviderValueComparer.Equals(
+                                        _currentValue,
+                                        Update.ColumnModification.GetCurrentProviderValue(entry, property))))
                             || (_originalValueInitialized
                                 && mapping.Column.ProviderValueComparer.Equals(
                                     Update.ColumnModification.GetCurrentProviderValue(entry, property),

test/EFCore.Relational.Specification.Tests/Update/UpdatesRelationalTestBase.cs

@@ -260,6 +260,30 @@ public virtual Task Update_non_indexed_values()
             });
     }
 
+    [ConditionalTheory, InlineData(false), InlineData(true)] // Issue #37525
+    public virtual async Task Can_save_owned_entity_with_default_values_in_TPH_with_shared_columns(bool async)
+        => await ExecuteWithStrategyInTransactionAsync(
+            async context =>
+            {
+                var entity = new CrunchyNougat { Name = "Test" };
+                context.Add(entity);
+                _ = async ? await context.SaveChangesAsync() : context.SaveChanges();
+            },
+            async context =>
+            {
+                var entity = await context.Set<CrunchyNougat>().SingleAsync();
+                Assert.Null(entity.Filling);
+                entity.Filling = new NougatFilling();
+                _ = async ? await context.SaveChangesAsync() : context.SaveChanges();
+            },
+            async context =>
+            {
+                var entity = await context.Set<CrunchyNougat>().SingleAsync();
+                Assert.NotNull(entity.Filling);
+                Assert.Equal(NougatFillingKind.Unknown, entity.Filling.Kind);
+                Assert.False(entity.Filling.IsFresh);
+            });
+
     [ConditionalFact]
     public abstract void Identifiers_are_generated_correctly();
 
@@ -301,6 +325,23 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
                     .HasColumnName("ZipCode");
             });
 
+            modelBuilder.Entity<CrunchyNougat>(b =>
+            {
+                b.OwnsOne(e => e.Filling, ob =>
+                {
+                    ob.Property(o => o.Kind).HasColumnName("FillingKind");
+                    ob.Property(o => o.IsFresh).HasColumnName("FillingIsFresh");
+                });
+            });
+            modelBuilder.Entity<SoftNougat>(b =>
+            {
+                b.OwnsOne(e => e.Filling, ob =>
+                {
+                    ob.Property(o => o.Kind).HasColumnName("FillingKind");
+                    ob.Property(o => o.IsFresh).HasColumnName("FillingIsFresh");
+                });
+            });
+
             modelBuilder
                 .Entity<
                     LoginEntityTypeWithAnExtremelyLongAndOverlyConvolutedNameThatIsUsedToVerifyThatTheStoreIdentifierGenerationLengthLimitIsWorkingCorrectlyDetails

test/EFCore.Specification.Tests/TestModels/UpdatesModel/Nougat.cs

@@ -0,0 +1,35 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.EntityFrameworkCore.TestModels.UpdatesModel;
+
+#nullable disable
+
+public abstract class Nougat
+{
+    public int Id { get; set; }
+    public string Name { get; set; }
+}
+
+public class CrunchyNougat : Nougat
+{
+    public NougatFilling Filling { get; set; }
+}
+
+public class SoftNougat : Nougat
+{
+    public NougatFilling Filling { get; set; }
+}
+
+public class NougatFilling
+{
+    public NougatFillingKind Kind { get; set; }
+    public bool IsFresh { get; set; }
+}
+
+public enum NougatFillingKind
+{
+    Unknown = 0,
+    Peanut = 1,
+    Almond = 2,
+}

test/EFCore.Specification.Tests/TestModels/UpdatesModel/UpdatesContext.cs

@@ -15,6 +15,8 @@ public class UpdatesContext(DbContextOptions options) : PoolableDbContext(option
     public DbSet<ProductTableWithView> ProductTable { get; set; } = null!;
     public DbSet<ProductTableView> ProductTableView { get; set; } = null!;
     public DbSet<Rodney> Trotters { get; set; } = null!;
+    public DbSet<CrunchyNougat> CrunchyNougats { get; set; } = null!;
+    public DbSet<SoftNougat> SoftNougats { get; set; } = null!;
 
     public static Task SeedAsync(UpdatesContext context)
     {

test/EFCore.Specification.Tests/Update/UpdatesTestBase.cs

@@ -1042,6 +1042,22 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
             modelBuilder.Entity<LiftObscurer>().HasOne<Lift>().WithOne(x => x.Obscurer).HasForeignKey<LiftObscurer>(e => e.LiftId);
             modelBuilder.Entity<LiftBag>();
             modelBuilder.Entity<LiftPaper>();
+
+            modelBuilder.Entity<Nougat>();
+            modelBuilder.Entity<CrunchyNougat>(b =>
+            {
+                b.OwnsOne(e => e.Filling, ob =>
+                {
+                    ob.Property(o => o.Kind).HasConversion<string>();
+                });
+            });
+            modelBuilder.Entity<SoftNougat>(b =>
+            {
+                b.OwnsOne(e => e.Filling, ob =>
+                {
+                    ob.Property(o => o.Kind).HasConversion<string>();
+                });
+            });
         }
 
         protected override Task SeedAsync(UpdatesContext context)