Query: Use GetDiscriminatorValue for TPT and TPC

Add model validation when values are not unique
Resolves #28054

src/EFCore.Relational/Infrastructure/RelationalModelValidator.cs

@@ -1391,6 +1391,24 @@ protected override void ValidateInheritanceMapping(
 
  ValidateNonTphMapping(entityType, forTables: false);
  ValidateNonTphMapping(entityType, forTables: true);
+
+ var derivedTypes = entityType.GetDerivedTypesInclusive().ToList();
+ var discriminatorValues = new Dictionary<object, IEntityType>();
+ foreach (var derivedType in derivedTypes)
+ {
+ if (!derivedType.ClrType.IsInstantiable())
+ {
+ continue;
+ }
+ var discriminatorValue = derivedType.ShortName();
+
+ if (discriminatorValues.TryGetValue(discriminatorValue, out var duplicateEntityType))
+ {
+ throw new InvalidOperationException("TBD");
+ }
+
+ discriminatorValues[discriminatorValue] = derivedType;
+ }
  }
  }
 
@@ -1469,7 +1487,7 @@ private static void ValidateNonTphMapping(IEntityType rootEntityType, bool forTa
  {
  return;
  }
- 
+
  var internalForeignKey = rootEntityType.FindRowInternalForeignKeys(storeObject.Value).FirstOrDefault();
  if (internalForeignKey != null
  && derivedTypes.Count > 1

src/EFCore.Relational/Metadata/Internal/RelationalEntityTypeExtensions.cs

@@ -31,15 +31,6 @@ public static IEnumerable<ITableMappingBase> GetViewOrTableMappings(this IEntity
  ?? entityType.FindRuntimeAnnotationValue(RelationalAnnotationNames.TableMappings))
  ?? Enumerable.Empty<ITableMappingBase>();
 
- /// <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 static IReadOnlyList<string> GetTptDiscriminatorValues(this IReadOnlyEntityType entityType)
- => entityType.GetConcreteDerivedTypesInclusive().Select(et => et.ShortName()).ToList();
-
  /// <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

src/EFCore.Relational/Query/EntityProjectionExpression.cs

@@ -123,7 +123,7 @@ public virtual EntityProjectionExpression UpdateEntityType(IEntityType derivedTy
  var discriminatorExpression = DiscriminatorExpression;
  if (DiscriminatorExpression is CaseExpression caseExpression)
  {
- var entityTypesToSelect = derivedType.GetTptDiscriminatorValues();
+ var entityTypesToSelect = derivedType.GetConcreteDerivedTypesInclusive().Select(e => e.GetDiscriminatorValue()).ToList();
  var whenClauses = caseExpression.WhenClauses
  .Where(wc => entityTypesToSelect.Contains((string)((SqlConstantExpression)wc.Result).Value!))
  .ToList();

src/EFCore.Relational/Query/RelationalSqlTranslatingExpressionVisitor.cs

@@ -1066,7 +1066,7 @@ protected override Expression VisitTypeBinary(TypeBinaryExpression typeBinaryExp
  }
 
  // TPT or TPC
- var discriminatorValues = derivedType.GetTptDiscriminatorValues();
+ var discriminatorValues = derivedType.GetConcreteDerivedTypesInclusive().Select(e => e.GetDiscriminatorValue()).ToList();
  if (entityReferenceExpression.SubqueryEntity != null)
  {
  var entityShaper = (EntityShaperExpression)entityReferenceExpression.SubqueryEntity.ShaperExpression;

src/EFCore/Metadata/IReadOnlyEntityType.cs

@@ -70,7 +70,8 @@ bool GetIsDiscriminatorMappingComplete()
  /// </summary>
  /// <returns>The discriminator value for this entity type.</returns>
  object? GetDiscriminatorValue()
- => this[CoreAnnotationNames.DiscriminatorValue];
+ => this[CoreAnnotationNames.DiscriminatorValue]
+ ?? (GetDiscriminatorPropertyName() == null ? (object)ShortName() : null);
 
  /// <summary>
  /// Gets all types in the model from which a given entity type derives, starting with the root.

test/EFCore.Relational.Tests/Infrastructure/RelationalModelValidatorTest.cs

@@ -485,9 +485,9 @@ public virtual void Passes_for_incompatible_uniquified_check_constraints_with_sh
  var modelBuilder = CreateConventionalModelBuilder();
 
  modelBuilder.Entity<A>().HasOne<B>().WithOne(b => b.A).HasForeignKey<A>(a => a.Id).HasPrincipalKey<B>(b => b.Id).IsRequired();
-  modelBuilder.Entity<A>().HasCheckConstraint("CK_Table_SomeCK", "Id > 0");
+ modelBuilder.Entity<A>().HasCheckConstraint("CK_Table_SomeCK", "Id > 0");
  modelBuilder.Entity<A>().ToTable("Table");
-  modelBuilder.Entity<B>().HasCheckConstraint("CK_Table_SomeCK", "Id > 10");
+ modelBuilder.Entity<B>().HasCheckConstraint("CK_Table_SomeCK", "Id > 10");
  modelBuilder.Entity<B>().ToTable("Table");
 
  var model = Validate(modelBuilder);
@@ -502,9 +502,9 @@ public virtual void Passes_for_compatible_shared_check_constraints_with_shared_t
  var modelBuilder = CreateConventionalModelBuilder();
 
  modelBuilder.Entity<A>().HasOne<B>().WithOne(b => b.A).HasForeignKey<A>(a => a.Id).HasPrincipalKey<B>(b => b.Id).IsRequired();
-  modelBuilder.Entity<A>().HasCheckConstraint("CK_Table_SomeCK", "Id > 0");
+ modelBuilder.Entity<A>().HasCheckConstraint("CK_Table_SomeCK", "Id > 0");
  modelBuilder.Entity<A>().ToTable("Table");
-  modelBuilder.Entity<B>().HasCheckConstraint("CK_Table_SomeCK", "Id > 0");
+ modelBuilder.Entity<B>().HasCheckConstraint("CK_Table_SomeCK", "Id > 0");
  modelBuilder.Entity<B>().ToTable("Table");
 
  var model = Validate(modelBuilder);
@@ -1853,7 +1853,7 @@ public virtual void Detects_clashing_entity_types_in_views_TPC()
  modelBuilder.Entity<Animal>().UseTpcMappingStrategy();
  modelBuilder.Entity<Cat>().ToTable("Cat").ToView("Cat");
  modelBuilder.Entity<Dog>().ToTable("Dog").ToView("Cat");
- 
+
  VerifyError(
  RelationalStrings.NonTphViewClash(nameof(Dog), nameof(Cat), "Cat"),
  modelBuilder);
@@ -1945,7 +1945,7 @@ public virtual void Passes_on_valid_view_sharing_with_TPC()
 
  Validate(modelBuilder);
  }
- 
+
  [ConditionalFact]
  public virtual void Detects_view_sharing_on_base_with_TPC()
  {
@@ -2511,6 +2511,38 @@ public virtual void Detects_triggers_on_unmapped_entity_types()
  VerifyError(RelationalStrings.TriggerOnUnmappedEntityType("Animal_Trigger", "Animal"), modelBuilder);
  }
 
+ [ConditionalFact]
+ public virtual void Throws_when_non_tph_entity_type_short_names_are_not_unique()
+ {
+ var modelBuilder = CreateConventionalModelBuilder();
+ modelBuilder.Entity<TpcBase>().UseTpcMappingStrategy();
+ modelBuilder.Entity<Outer.TpcDerived>().ToTable("TpcDerived1");
+ modelBuilder.Entity<Outer2.TpcDerived>().ToTable("TpcDerived2");
+
+ VerifyError("TBD", modelBuilder);
+ }
+
+ private class TpcBase
+ {
+ public int Id { get; set; }
+ }
+
+ private class Outer
+ {
+ public class TpcDerived : TpcBase
+ {
+ public string Value { get; set; }
+ }
+ }
+
+ private class Outer2
+ {
+ public class TpcDerived : TpcBase
+ {
+ public string Value { get; set; }
+ }
+ }
+
  protected override void SetBaseType(IMutableEntityType entityType, IMutableEntityType baseEntityType)
  {
  base.SetBaseType(entityType, baseEntityType);