Fix NRE in FindJsonPartialUpdateInfo when replacing TPH derived entity with owned JSON

src/EFCore.Relational/Update/ModificationCommand.cs

@@ -594,6 +594,13 @@ void HandleSharedColumns(
                     (InternalEntityEntry)currentEntry, currentOwnership)!;
 #pragma warning restore EF1001 // Internal EF Core API usage.
 
+                // principal entity was replaced with a different derived type (e.g. TPH),
+                // no need to do any json-specific processing
+                if (currentEntry == null)
+                {
+                    return null;
+                }
+
                 if (processedEntries.Contains(currentEntry))
                 {
                     return null;

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

@@ -200,6 +200,38 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
             b.Property(x => x.Name);
         });
 
+        modelBuilder.Entity<JsonEntityTphItem>(b =>
+        {
+            b.Property(x => x.Id).ValueGeneratedNever();
+            b.HasMany(x => x.Attributes).WithOne().HasForeignKey(x => x.JsonEntityTphItemId);
+        });
+
+        modelBuilder.Entity<JsonEntityTphItemAttribute>(b =>
+        {
+            b.HasKey(x => new { x.JsonEntityTphItemId, x.Key });
+            b.HasDiscriminator<string>("Discriminator")
+                .HasValue<JsonEntityTphStringAttribute>("string")
+                .HasValue<JsonEntityTphLocaleAttribute>("locale-value");
+        });
+
+        modelBuilder.Entity<JsonEntityTphStringAttribute>(b =>
+        {
+            b.Property(x => x.Value).HasColumnName("StringValue");
+        });
+
+        modelBuilder.Entity<JsonEntityTphLocaleAttribute>(b =>
+        {
+            b.OwnsOne(x => x.Value, bc =>
+            {
+                bc.ToJson("LocaleValue");
+                bc.OwnsMany(x => x.Entries, v =>
+                {
+                    v.Property(x => x.Locale).IsRequired();
+                    v.Property(x => x.Value);
+                });
+            });
+        });
+
         base.OnModelCreating(modelBuilder, context);
     }
 
@@ -209,11 +241,13 @@ protected override Task SeedAsync(JsonQueryContext context)
         var jsonEntitiesInheritance = JsonQueryData.CreateJsonEntitiesInheritance();
         var jsonEntitiesAllTypes = JsonQueryData.CreateJsonEntitiesAllTypes();
         var jsonEntitiesConverters = JsonQueryData.CreateJsonEntitiesConverters();
+        var jsonEntitiesTphItems = JsonQueryData.CreateJsonEntitiesTphItems();
 
         context.JsonEntitiesBasic.AddRange(jsonEntitiesBasic);
         context.JsonEntitiesInheritance.AddRange(jsonEntitiesInheritance);
         context.JsonEntitiesAllTypes.AddRange(jsonEntitiesAllTypes);
         context.JsonEntitiesConverters.AddRange(jsonEntitiesConverters);
+        context.JsonEntitiesTphItems.AddRange(jsonEntitiesTphItems);
 
         return context.SaveChangesAsync();
     }

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

@@ -3732,6 +3732,34 @@ public virtual Task Replace_json_reference_root_preserves_nested_owned_entities_
                 Assert.NotNull(result.OwnedReferenceRoot.OwnedReferenceBranch.OwnedReferenceLeaf);
             });
 
+    [ConditionalFact]
+    public virtual Task Replace_derived_entity_with_json_to_different_derived_type_with_same_key()
+        => TestHelpers.ExecuteWithStrategyInTransactionAsync(
+            CreateContext,
+            UseTransaction,
+            async context =>
+            {
+                var item = await context.JsonEntitiesTphItems.Include(x => x.Attributes).SingleAsync();
+
+                item.Attributes.RemoveAll(attr => attr.Key == "TextValue");
+                item.Attributes.Add(new JsonEntityTphStringAttribute
+                {
+                    Key = "TextValue",
+                    Value = "World"
+                });
+
+                ClearLog();
+                await context.SaveChangesAsync();
+            },
+            async context =>
+            {
+                var item = await context.JsonEntitiesTphItems.Include(x => x.Attributes).SingleAsync();
+                var attribute = Assert.Single(item.Attributes);
+                var stringAttribute = Assert.IsType<JsonEntityTphStringAttribute>(attribute);
+                Assert.Equal("TextValue", stringAttribute.Key);
+                Assert.Equal("World", stringAttribute.Value);
+            });
+
     public void UseTransaction(DatabaseFacade facade, IDbContextTransaction transaction)
         => facade.UseTransaction(transaction.GetDbTransaction());
 

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonEntityTphItem.cs

@@ -0,0 +1,13 @@
+// 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.JsonQuery;
+
+#nullable disable
+
+public class JsonEntityTphItem
+{
+    public int Id { get; set; }
+    public string Name { get; set; }
+    public List<JsonEntityTphItemAttribute> Attributes { get; set; }
+}

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonEntityTphItemAttribute.cs

@@ -0,0 +1,12 @@
+// 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.JsonQuery;
+
+#nullable disable
+
+public abstract class JsonEntityTphItemAttribute
+{
+    public int JsonEntityTphItemId { get; set; }
+    public string Key { get; set; }
+}

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonEntityTphLocaleAttribute.cs

@@ -0,0 +1,11 @@
+// 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.JsonQuery;
+
+#nullable disable
+
+public class JsonEntityTphLocaleAttribute : JsonEntityTphItemAttribute
+{
+    public JsonOwnedTphLocaleValue Value { get; set; }
+}

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonEntityTphStringAttribute.cs

@@ -0,0 +1,11 @@
+// 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.JsonQuery;
+
+#nullable disable
+
+public class JsonEntityTphStringAttribute : JsonEntityTphItemAttribute
+{
+    public string Value { get; set; }
+}

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonOwnedTphLocaleValue.cs

@@ -0,0 +1,11 @@
+// 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.JsonQuery;
+
+#nullable disable
+
+public class JsonOwnedTphLocaleValue
+{
+    public List<JsonOwnedTphLocaleValueEntry> Entries { get; set; }
+}

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonOwnedTphLocaleValueEntry.cs

@@ -0,0 +1,12 @@
+// 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.JsonQuery;
+
+#nullable disable
+
+public class JsonOwnedTphLocaleValueEntry
+{
+    public string Locale { get; set; }
+    public string Value { get; set; }
+}

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonQueryContext.cs

@@ -16,6 +16,7 @@ public class JsonQueryContext(DbContextOptions options) : DbContext(options)
     public DbSet<JsonEntityInheritanceBase> JsonEntitiesInheritance { get; set; }
     public DbSet<JsonEntityAllTypes> JsonEntitiesAllTypes { get; set; }
     public DbSet<JsonEntityConverters> JsonEntitiesConverters { get; set; }
+    public DbSet<JsonEntityTphItem> JsonEntitiesTphItems { get; set; }
 
     public static Task SeedAsync(JsonQueryContext context)
     {

test/EFCore.Specification.Tests/TestModels/JsonQuery/JsonQueryData.cs

@@ -22,6 +22,7 @@ public JsonQueryData()
         JsonEntitiesInheritance = CreateJsonEntitiesInheritance();
         JsonEntitiesAllTypes = CreateJsonEntitiesAllTypes();
         JsonEntitiesConverters = CreateJsonEntitiesConverters();
+        JsonEntitiesTphItems = CreateJsonEntitiesTphItems();
     }
 
     public IReadOnlyList<EntityBasic> EntitiesBasic { get; }
@@ -33,6 +34,7 @@ public JsonQueryData()
     public IReadOnlyList<JsonEntityInheritanceBase> JsonEntitiesInheritance { get; set; }
     public IReadOnlyList<JsonEntityAllTypes> JsonEntitiesAllTypes { get; set; }
     public IReadOnlyList<JsonEntityConverters> JsonEntitiesConverters { get; set; }
+    public IReadOnlyList<JsonEntityTphItem> JsonEntitiesTphItems { get; set; }
 
     public static IReadOnlyList<JsonEntityBasic> CreateJsonEntitiesBasic()
     {
@@ -1470,6 +1472,30 @@ public static IReadOnlyList<JsonEntityConverters> CreateJsonEntitiesConverters()
         };
     }
 
+    public static IReadOnlyList<JsonEntityTphItem> CreateJsonEntitiesTphItems()
+        => new List<JsonEntityTphItem>
+        {
+            new()
+            {
+                Id = 1,
+                Name = "Product 1",
+                Attributes =
+                [
+                    new JsonEntityTphLocaleAttribute
+                    {
+                        Key = "TextValue",
+                        Value = new JsonOwnedTphLocaleValue
+                        {
+                            Entries =
+                            [
+                                new JsonOwnedTphLocaleValueEntry { Locale = "en-US", Value = "Hello" }
+                            ]
+                        }
+                    }
+                ]
+            }
+        };
+
     public IQueryable<TEntity> Set<TEntity>()
         where TEntity : class
     {
@@ -1523,6 +1549,11 @@ public IQueryable<TEntity> Set<TEntity>()
             return (IQueryable<TEntity>)JsonEntitiesBasicForCollection.AsQueryable();
         }
 
+        if (typeof(TEntity) == typeof(JsonEntityTphItem))
+        {
+            return (IQueryable<TEntity>)JsonEntitiesTphItems.AsQueryable();
+        }
+
         throw new InvalidOperationException("Invalid entity type: " + typeof(TEntity));
     }
 }

test/EFCore.SqlServer.FunctionalTests/Update/JsonUpdateJsonTypeSqlServerFixture.cs

@@ -68,5 +68,10 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
         });
 
         modelBuilder.Entity<JsonEntityConverters>().OwnsOne(x => x.Reference).ToJson().HasColumnType("json");
+
+        modelBuilder.Entity<JsonEntityTphLocaleAttribute>(b =>
+        {
+            b.OwnsOne(x => x.Value).ToJson().HasColumnType("json");
+        });
     }
 }

test/EFCore.SqlServer.FunctionalTests/Update/JsonUpdateJsonTypeSqlServerTest.cs

@@ -3299,6 +3299,11 @@ FROM [JsonEntitiesBasic] AS [j]
     protected override void ClearLog()
         => Fixture.TestSqlLoggerFactory.Clear();
 
+    public override async Task Replace_derived_entity_with_json_to_different_derived_type_with_same_key()
+    {
+        await base.Replace_derived_entity_with_json_to_different_derived_type_with_same_key();
+    }
+
     private void AssertSql(params string[] expected)
         => Fixture.TestSqlLoggerFactory.AssertBaseline(expected);
 }