EF 10: Nullable complex property with PropertyValues.ToObject() creates instance instead of null

[alienwareone]

Bug description

When using a nullable complex type configured with ComplexProperty, calling OriginalValues.ToObject() when the original complex property value is null creates a complex type instance instead of returning null (same for CurrentValues.ToObject()).

Your code

#:package Npgsql.EntityFrameworkCore.PostgreSQL@10.0.0
#:property PublishAot=false

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

await using var context = new ProductContext();
await context.Database.EnsureDeletedAsync();
await context.Database.EnsureCreatedAsync();

context.Products.Add(new() { Name = "Product 1" });
await context.SaveChangesAsync();

context.ChangeTracker.Clear();
var product = await context.Products.FirstAsync();
var originalProduct = context.ChangeTracker.Entries().First().OriginalValues.ToObject();
;

public sealed class ProductContext : DbContext
{
    public DbSet<Product> Products { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder
            .UseNpgsql("Host=localhost;Username=postgres;Password=postgres;Database=Test")
            .LogTo(Console.WriteLine, LogLevel.Information)
            .EnableSensitiveDataLogging();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
        => modelBuilder.Entity<Product>().ComplexProperty(x => x.Price);
}

public sealed class Product
{
    public int Id { get; private set; }
    public required string Name { get; set; }
    public Price? Price { get; set; }
}

public sealed class Price
{
    public required decimal Amount { get; init; }
    public required int CurrencyId { get; init; }
}

Stack traces

Verbose output

EF Core version

10.0.0

Database provider

Npgsql.EntityFrameworkCore.PostgreSQL

Target framework

.NET 10.0

Operating system

Windows 11

IDE

VSCode

[alienwareone]

Seems like the problem only occurs when the first required complex-type property is a value-type. Tested with reference-types (like strings) and the problem is gone.

[roji]

@AndriySvyryd here's a minimal SQL Server repro (very close to the above), in case it helps:

Minimal repro with SQL Server

await using var context = new ProductContext();
await context.Database.EnsureDeletedAsync();
await context.Database.EnsureCreatedAsync();

context.Products.Add(new() { Name = "Product 1" });
await context.SaveChangesAsync();

context.ChangeTracker.Clear();
var product = await context.Products.FirstAsync();
var originalProduct = (Product)context.ChangeTracker.Entries().First().OriginalValues.ToObject();
Console.WriteLine("Original Product: " + originalProduct.Price?.Amount); // 0, should be null

public sealed class ProductContext : DbContext
{
    public DbSet<Product> Products { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder
            .UseSqlServer(Environment.GetEnvironmentVariable("Test__SqlServer__DefaultConnection"))
            .LogTo(Console.WriteLine, LogLevel.Information)
            .EnableSensitiveDataLogging();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
        => modelBuilder.Entity<Product>().ComplexProperty(x => x.Price);
}

public sealed class Product
{
    public int Id { get; private set; }
    public required string Name { get; set; }
    public Price? Price { get; set; }
}

public sealed class Price
{
    public required decimal Amount { get; init; }
    public required int CurrencyId { get; init; }
}