Treat required owned entities on derived types as optional.

Fixes #31107

src/EFCore.Relational/Query/SqlExpressions/SelectExpression.cs

@@ -29,6 +29,8 @@ public sealed partial class SelectExpression : TableExpressionBase
 
  private static readonly bool UseOldBehavior30273
  = AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue30273", out var enabled30273) && enabled30273;
+ private static readonly bool UseOldBehavior31107 =
+ AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue31107", out var enabled31107) && enabled31107;
 
  private static readonly IdentifierComparer IdentifierComparerInstance = new();
 
@@ -2637,7 +2639,9 @@ static IReadOnlyDictionary<IProperty, ColumnExpression> GetPropertyExpressions(
  var parentNullable = identifyingColumn.IsNullable;
  var pkColumnsNullable = parentNullable
  || (derivedType && ownerType.GetMappingStrategy() != RelationalAnnotationNames.TphMappingStrategy);
- var newColumnsNullable = pkColumnsNullable || !navigation.ForeignKey.IsRequiredDependent;
+ var newColumnsNullable = pkColumnsNullable
+ || !navigation.ForeignKey.IsRequiredDependent
+ || (derivedType && !UseOldBehavior31107);
  if (derivedTpt)
  {
  principalMappings = principalMappings.Except(ownerType.BaseType!.GetViewOrTableMappings().Select(e => e.Table));

test/EFCore.Relational.Specification.Tests/Query/OwnedEntityQueryRelationalTestBase.cs

@@ -408,27 +408,27 @@ public void Seed()
  }
  }
 
- public class RotRutCase
+ protected class RotRutCase
  {
  public int Id { get; set; }
  public string Buyer { get; set; }
  public Rot Rot { get; set; }
  public Rut Rut { get; set; }
  }
 
- public class Rot
+ protected class Rot
  {
  public int? ServiceType { get; set; }
  public string ApartmentNo { get; set; }
  }
 
- public class RotDto
+ protected class RotDto
  {
  public int? MyServiceType { get; set; }
  public string MyApartmentNo { get; set; }
  }
 
- public class Rut
+ protected class Rut
  {
  public int? Value { get; set; }
  }
@@ -498,26 +498,84 @@ public void Seed()
  }
  }
 
- public class Monarch30358
+ protected class Monarch30358
  {
  public int Id { get; set; }
  public string Name { get; set; }
  public string RulerOf { get; set; }
  }
 
- public class Magus30358
+ protected class Magus30358
  {
  public int Id { get; set; }
  public string Name { get; set; }
  public string Affiliation { get; set; }
  public MagicTool30358 ToolUsed { get; set; }
  }
 
- public class MagicTool30358
+ protected class MagicTool30358
  {
  public string Name { get; set; }
  }
 
+ protected abstract class BaseEntity31107
+ {
+ public Guid Id { get; set; }
+ }
+
+ protected sealed class ChildData31107
+ {
+ public Guid Id { get; set; }
+ }
+
+ protected sealed class Child1Entity31107 : BaseEntity31107
+ {
+ public ChildData31107 Data { get; set; }
+ }
+
+ protected sealed class Child2Entity31107 : BaseEntity31107
+ {
+ }
+
+ [ConditionalFact]
+ public async Task Can_have_required_owned_type_on_derived_type()
+ {
+ var contextFactory = await InitializeAsync<RequiredNavigationContext>(seed: c => c.Seed());
+ using var context = contextFactory.CreateContext();
+
+ context.Set<BaseEntity31107>().ToList();
+ }
+
+ private class RequiredNavigationContext : DbContext
+ {
+ public RequiredNavigationContext(DbContextOptions options)
+ : base(options)
+ {
+ }
+
+ protected override void OnModelCreating(ModelBuilder modelBuilder)
+ {
+ modelBuilder.Entity<BaseEntity31107>();
+ modelBuilder.Entity<Child1Entity31107>(b =>
+ {
+ b.OwnsOne(entity => entity.Data, builder =>
+ {
+ builder.ToTable("Child1EntityData");
+ builder.WithOwner().HasForeignKey("Child1EntityId");
+ });
+ b.Navigation(e => e.Data).IsRequired();
+ });
+
+ modelBuilder.Entity<Child2Entity31107>();
+ }
+ public void Seed()
+ {
+ Add(new Child2Entity31107 { Id = Guid.NewGuid() });
+
+ SaveChanges();
+ }
+ }
+
  protected override DbContextOptionsBuilder AddOptions(DbContextOptionsBuilder builder)
  => base.AddOptions(builder).ConfigureWarnings(
  c => c