OriginalValue access on ComplexCollections not working for Entites in Added State #38486

using Microsoft.EntityFrameworkCore;

// -------------------------------------------------------------------
// EF Core 10 – Bug repro: ComplexCollection does not support OriginalValues
// when the entity is in the 'Added' state, causing OriginalValues.ToObject()
// to throw InvalidOperationException.
// -------------------------------------------------------------------

using var db = new OrderContext();
db.Database.EnsureCreated();

var order = new Order
{
    Id = 1,
    Name = "Demo Order",
    LineItems =
    [
        new LineItem { Product = "Widget", Quantity = 2 },
        new LineItem { Product = "Gadget", Quantity = 5 },
    ]
};

db.Orders.Add(order);

var entry = db.Entry(order);
Console.WriteLine($"Entity state : {entry.State}");   // Added

// CurrentValues works fine.
Console.WriteLine($"CurrentValues[\"Name\"] : {entry.CurrentValues["Name"]}");

// OriginalValues on a plain scalar property also works for Added (EF copies it from current).
Console.WriteLine($"OriginalValues[\"Name\"] : {entry.OriginalValues["Name"]}");

// OriginalValues.ToObject() fails when a ComplexCollection is present on an Added entity.
// EF Core has no original-value snapshot for complex-collection elements yet, so it throws:
//   "The complex entry at the original ordinal '0' for the collection 'Order.LineItems'
//    cannot be accessed as the containing entry is in the added state."
Console.WriteLine();
Console.WriteLine("Calling entry.OriginalValues.ToObject() ...");
try
{
    var original = entry.OriginalValues.ToObject();   // <-- throws!
    Console.WriteLine($"Original object: {original}");
}
catch (InvalidOperationException ex)
{
    Console.ForegroundColor = ConsoleColor.Red;
    Console.WriteLine($"[InvalidOperationException] {ex.Message}");
    Console.ResetColor();
}

Console.WriteLine("\nDone.");

// ── Model ──────────────────────────────────────────────────────────

public class Order
{
    public int Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public List<LineItem> LineItems { get; set; } = [];
}

public class LineItem
{
    public string Product { get; set; } = string.Empty;
    public int Quantity { get; set; }
}

// ── DbContext ──────────────────────────────────────────────────────

public class OrderContext : DbContext
{
    public DbSet<Order> Orders => Set<Order>();

    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options.UseSqlite("Data Source=demo.db");

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        // ComplexCollection requires ToJson() for relational providers.
        modelBuilder.Entity<Order>()
            .ComplexCollection(o => o.LineItems, b => b.ToJson());
    }
}