Fix duplicate JSON column in TPT child tables for complex types declared on base entity type

When a complex property is mapped to JSON on a base entity type in a TPT
hierarchy, the JSON column was being incorrectly created in child tables
in addition to the base table. This is because `GetComplexProperties()`
returns inherited properties, and there was no equivalent of the
`GetColumnName(mappedTable) == null` filter used for scalar properties.

The fix adds a check in `CreateTableMapping` to skip complex properties
declared on base entity types that map to a different table (TPT scenario).
TPC is excluded from this check since each TPC concrete table needs all
properties including inherited ones.

Fixes #38535

Author: Copilot

src/EFCore.Relational/EFCore.Relational.baseline.json

@@ -7352,10 +7352,10 @@
           "Member": "virtual Microsoft.EntityFrameworkCore.Query.JsonQueryExpression BindStructuralProperty(Microsoft.EntityFrameworkCore.Metadata.IPropertyBase structuralProperty);"
         },
         {
-          "Member": "virtual Microsoft.EntityFrameworkCore.Metadata.IRelationalJsonElement? FindJsonElement(Microsoft.EntityFrameworkCore.Metadata.IPropertyBase propertyBase);"
+          "Member": "override bool Equals(object? obj);"
         },
         {
-          "Member": "override bool Equals(object? obj);"
+          "Member": "virtual Microsoft.EntityFrameworkCore.Metadata.IRelationalJsonElement? FindJsonElement(Microsoft.EntityFrameworkCore.Metadata.IPropertyBase propertyBase);"
         },
         {
           "Member": "override int GetHashCode();"
@@ -17425,6 +17425,9 @@
         {
           "Member": "static string? GetContainerColumnName(this Microsoft.EntityFrameworkCore.Metadata.IReadOnlyTypeBase typeBase);"
         },
+        {
+          "Member": "static string? GetContainerColumnName(this Microsoft.EntityFrameworkCore.Metadata.IReadOnlyTypeBase typeBase, in Microsoft.EntityFrameworkCore.Metadata.StoreObjectIdentifier storeObject);"
+        },
         {
           "Member": "static Microsoft.EntityFrameworkCore.Metadata.ConfigurationSource? GetContainerColumnNameConfigurationSource(this Microsoft.EntityFrameworkCore.Metadata.IConventionTypeBase typeBase);"
         },

src/EFCore.Relational/Extensions/RelationalTypeBaseExtensions.cs

@@ -388,6 +388,73 @@ public static bool IsMappedToJson(this IReadOnlyTypeBase typeBase)
                 : ((IReadOnlyComplexType)typeBase).ComplexProperty.DeclaringType.GetContainerColumnName();
     }
 
+    /// <summary>
+    ///     Gets the container column name to which the type is mapped for a particular table-like store object.
+    /// </summary>
+    /// <param name="typeBase">The type to get the container column name for.</param>
+    /// <param name="storeObject">The identifier of the table-like store object containing the column.</param>
+    /// <returns>
+    ///     The container column name to which the type is mapped, or <see langword="null" /> if the type is not mapped
+    ///     to a container column in the given store object.
+    /// </returns>
+    public static string? GetContainerColumnName(this IReadOnlyTypeBase typeBase, in StoreObjectIdentifier storeObject)
+    {
+        var annotation = typeBase.FindAnnotation(RelationalAnnotationNames.ContainerColumnName);
+        if (annotation != null)
+        {
+            var containerColumnName = (string?)annotation.Value;
+            if (string.IsNullOrEmpty(containerColumnName))
+            {
+                return containerColumnName;
+            }
+
+            if (storeObject.StoreObjectType is StoreObjectType.Function or StoreObjectType.SqlQuery)
+            {
+                return containerColumnName;
+            }
+
+            var containingEntityType = typeBase.ContainingEntityType;
+            if (containingEntityType.GetMappingStrategy() == RelationalAnnotationNames.TpcMappingStrategy)
+            {
+                return containerColumnName;
+            }
+
+            var declaringStoreObject = StoreObjectIdentifier.Create(typeBase, storeObject.StoreObjectType);
+            if (declaringStoreObject == null)
+            {
+                var tableFound = false;
+                var queue = new Queue<IReadOnlyEntityType>();
+                queue.Enqueue(containingEntityType);
+                while (queue.Count > 0 && !tableFound)
+                {
+                    foreach (var derivedType in queue.Dequeue().GetDirectlyDerivedTypes())
+                    {
+                        var derivedStoreObject = StoreObjectIdentifier.Create(derivedType, storeObject.StoreObjectType);
+                        if (derivedStoreObject == null)
+                        {
+                            queue.Enqueue(derivedType);
+                            continue;
+                        }
+
+                        if (derivedStoreObject == storeObject)
+                        {
+                            tableFound = true;
+                            break;
+                        }
+                    }
+                }
+
+                return tableFound ? containerColumnName : null;
+            }
+
+            return declaringStoreObject == storeObject ? containerColumnName : null;
+        }
+
+        return typeBase is IReadOnlyEntityType entityType
+            ? entityType.FindOwnership()?.PrincipalEntityType.GetContainerColumnName(storeObject)
+            : ((IReadOnlyComplexType)typeBase).ComplexProperty.DeclaringType.GetContainerColumnName(storeObject);
+    }
+
     /// <summary>
     ///     Sets the name of the container column to which the type is mapped.
     /// </summary>

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

@@ -509,7 +509,7 @@ private static void CreateTableMapping(
             IsSplitEntityTypePrincipal = isSplitEntityTypePrincipal
         };
 
-        var containerColumnName = mappedType.GetContainerColumnName();
+        var containerColumnName = mappedType.GetContainerColumnName(mappedTable);
         var containerColumnType = mappedType.GetContainerColumnType();
         if (!string.IsNullOrEmpty(containerColumnName))
         {

test/EFCore.Relational.Tests/Metadata/RelationalModelTest.cs

@@ -3381,6 +3381,122 @@ public void Complex_property_json_column_is_nullable_in_TPH_hierarchy()
             Assert.IsType<JsonColumn>(jsonColumn);
         }
 
+        [Fact]
+        public void Complex_property_json_column_is_not_duplicated_in_TPT_child_tables()
+        {
+            var modelBuilder = CreateConventionModelBuilder();
+
+            modelBuilder.Entity<TptBaseEntityWithComplexProperty>()
+                .UseTptMappingStrategy()
+                .ComplexProperty(e => e.ComplexProperty, b => b.ToJson());
+            modelBuilder.Entity<TptDerivedEntityWithoutComplexProperty>();
+
+            var model = modelBuilder.FinalizeModel();
+            var relationalModel = model.GetRelationalModel();
+
+            var baseTable = relationalModel.Tables.Single(t => t.Name == nameof(TptBaseEntityWithComplexProperty));
+            var childTable = relationalModel.Tables.Single(t => t.Name == nameof(TptDerivedEntityWithoutComplexProperty));
+
+            // The JSON column for the base complex property must appear only in the base table
+            Assert.Contains(baseTable.Columns, c => c.Name == nameof(TptBaseEntityWithComplexProperty.ComplexProperty));
+            Assert.DoesNotContain(childTable.Columns, c => c.Name == nameof(TptBaseEntityWithComplexProperty.ComplexProperty));
+        }
+
+        [Fact]
+        public void Complex_property_columns_are_not_duplicated_in_TPT_child_tables()
+        {
+            var modelBuilder = CreateConventionModelBuilder();
+
+            modelBuilder.Entity<TptBaseEntityWithComplexProperty>()
+                .UseTptMappingStrategy()
+                .ComplexProperty(e => e.ComplexProperty);
+            modelBuilder.Entity<TptDerivedEntityWithoutComplexProperty>();
+
+            var model = modelBuilder.FinalizeModel();
+            var relationalModel = model.GetRelationalModel();
+
+            var baseTable = relationalModel.Tables.Single(t => t.Name == nameof(TptBaseEntityWithComplexProperty));
+            var childTable = relationalModel.Tables.Single(t => t.Name == nameof(TptDerivedEntityWithoutComplexProperty));
+
+            // Non-JSON complex property columns appear only on the base table.
+            var valueColumnName = nameof(TptBaseEntityWithComplexProperty.ComplexProperty) + "_" + nameof(ComplexData.Value);
+            var numberColumnName = nameof(TptBaseEntityWithComplexProperty.ComplexProperty) + "_" + nameof(ComplexData.Number);
+            Assert.Contains(baseTable.Columns, c => c.Name == valueColumnName);
+            Assert.Contains(baseTable.Columns, c => c.Name == numberColumnName);
+            Assert.DoesNotContain(childTable.Columns, c => c.Name == valueColumnName);
+            Assert.DoesNotContain(childTable.Columns, c => c.Name == numberColumnName);
+        }
+
+        [Fact]
+        public void Complex_property_json_column_is_created_in_every_TPC_table()
+        {
+            var modelBuilder = CreateConventionModelBuilder();
+
+            modelBuilder.Entity<TpcBaseEntityWithComplexProperty>(b =>
+            {
+                b.UseTpcMappingStrategy();
+                b.ComplexProperty(e => e.ComplexProperty, cb => cb.ToJson());
+            });
+            modelBuilder.Entity<TpcDerivedEntityWithoutComplexProperty>();
+
+            var model = modelBuilder.FinalizeModel();
+            var relationalModel = model.GetRelationalModel();
+
+            var baseTable = relationalModel.Tables.Single(t => t.Name == nameof(TpcBaseEntityWithComplexProperty));
+            var derivedTable = relationalModel.Tables.Single(t => t.Name == nameof(TpcDerivedEntityWithoutComplexProperty));
+
+            // In TPC the JSON container column appears on every concrete table.
+            Assert.Contains(baseTable.Columns, c => c.Name == nameof(TpcBaseEntityWithComplexProperty.ComplexProperty));
+            Assert.Contains(derivedTable.Columns, c => c.Name == nameof(TpcBaseEntityWithComplexProperty.ComplexProperty));
+        }
+
+        [Fact]
+        public void GetContainerColumnName_with_StoreObjectIdentifier_resolves_per_table()
+        {
+            var modelBuilder = CreateConventionModelBuilder();
+
+            modelBuilder.Entity<TptBaseEntityWithComplexProperty>()
+                .UseTptMappingStrategy()
+                .ComplexProperty(e => e.ComplexProperty, cb => cb.ToJson());
+            modelBuilder.Entity<TptDerivedEntityWithoutComplexProperty>();
+
+            var model = modelBuilder.FinalizeModel();
+            var baseEntity = model.FindEntityType(typeof(TptBaseEntityWithComplexProperty))!;
+            var complexProperty = baseEntity.FindComplexProperty(nameof(TptBaseEntityWithComplexProperty.ComplexProperty))!;
+            var complexType = complexProperty.ComplexType;
+
+            var baseTable = StoreObjectIdentifier.Table(nameof(TptBaseEntityWithComplexProperty));
+            var childTable = StoreObjectIdentifier.Table(nameof(TptDerivedEntityWithoutComplexProperty));
+            var unrelatedTable = StoreObjectIdentifier.Table("SomeOtherTable");
+
+            Assert.Equal(nameof(TptBaseEntityWithComplexProperty.ComplexProperty), complexType.GetContainerColumnName(baseTable));
+            Assert.Null(complexType.GetContainerColumnName(childTable));
+            Assert.Null(complexType.GetContainerColumnName(unrelatedTable));
+        }
+
+        [Fact]
+        public void GetContainerColumnName_with_StoreObjectIdentifier_returns_column_for_every_TPC_table()
+        {
+            var modelBuilder = CreateConventionModelBuilder();
+
+            modelBuilder.Entity<TpcBaseEntityWithComplexProperty>(b =>
+            {
+                b.UseTpcMappingStrategy();
+                b.ComplexProperty(e => e.ComplexProperty, cb => cb.ToJson());
+            });
+            modelBuilder.Entity<TpcDerivedEntityWithoutComplexProperty>();
+
+            var model = modelBuilder.FinalizeModel();
+            var baseEntity = model.FindEntityType(typeof(TpcBaseEntityWithComplexProperty))!;
+            var complexProperty = baseEntity.FindComplexProperty(nameof(TpcBaseEntityWithComplexProperty.ComplexProperty))!;
+            var complexType = complexProperty.ComplexType;
+
+            var baseTable = StoreObjectIdentifier.Table(nameof(TpcBaseEntityWithComplexProperty));
+            var derivedTable = StoreObjectIdentifier.Table(nameof(TpcDerivedEntityWithoutComplexProperty));
+
+            Assert.Equal(nameof(TpcBaseEntityWithComplexProperty.ComplexProperty), complexType.GetContainerColumnName(baseTable));
+            Assert.Equal(nameof(TpcBaseEntityWithComplexProperty.ComplexProperty), complexType.GetContainerColumnName(derivedTable));
+        }
         [Fact]
         public void Json_element_tree_is_built_for_owned_entity_json_columns()
         {
@@ -3994,6 +4110,22 @@ private class TphEntityWithComplexProperty : TphBaseEntity
             public ComplexData ComplexProperty { get; set; }
         }
 
+        private abstract class TptBaseEntityWithComplexProperty
+        {
+            public int Id { get; set; }
+            public ComplexData ComplexProperty { get; set; }
+        }
+
+        private class TptDerivedEntityWithoutComplexProperty : TptBaseEntityWithComplexProperty;
+
+        private class TpcBaseEntityWithComplexProperty
+        {
+            public int Id { get; set; }
+            public ComplexData ComplexProperty { get; set; }
+        }
+
+        private class TpcDerivedEntityWithoutComplexProperty : TpcBaseEntityWithComplexProperty;
+
         private class EntityWithJsonOwnedWithCollection
         {
             public int Id { get; set; }