Saving related data in JSONB not performed automatically

[armanossiloko]

I noticed that if I have related data which is stored as JSONB, updating the related data through another entity will not performed unless I set context.Entry(entity).Property(u => u.Metadata).IsModified = true;. As an example, consider the scenario where I have a Person that has multiple addresses, like this:

public class Person
{
    public int Id { get; set; }
    public required string Name { get; set; }
    public List<Address> Addresses { get; set; } = [];
}
public class Address
{
    public int Id { get; set; }
    public string? StreetName { get; set; }
    public int PersonId { get; set; }
    public virtual Person? Person { get; set; }
    public Metadata Metadata { get; set; }
}
public class Metadata
{
    public int HouseNumber { get; set; }
    public string? Door { get; set; }
}

With a DbContext setup such as this:

public class MyDbContext(DbContextOptions<MyDbContext> options) : DbContext(options)
{
    public DbSet<Person> People { get; set; }
    public DbSet<Address> Addresses { get; set; }
    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);
        builder.Entity<Address>()
            .Property(e => e.Metadata)
            .HasColumnType("jsonb");
    }
}

Creating a Person would work just fine. All data would be inserted and nothing would be incorrect. However, in the /update endpoint, if I try to update an Address.Metadata through a Person, the Metadata properties won't be updated in the database unless I explicitly (for each address) declare that the Metadata has changes: context.Entry(address).Property(u => u.Metadata).IsModified = true;. Why is this the case

app.MapPost("/add", (MyDbContext context) =>
{
    Person person = new()
    { 
        Name = "Person 1", 
        Addresses = new()
        {
            new()
            {
                PersonId = 1,
                Metadata = new() { HouseNumber = 30, Door = "N/A" },
            }
        }
    };
    context.People.Add(person);
    context.SaveChanges();
    return Results.Ok();
});
app.MapPost("/update", (MyDbContext context) =>
{
    var person = context.People.Include(x => x.Addresses).FirstOrDefault(x => x.Id == 1);
    foreach (var address in person.Addresses)
    {
        address.Metadata.HouseNumber = 36;
        address.Metadata.Door = "John Doe";

        //context.Entry(address).Property(u => u.Metadata).IsModified = true;
        // Without the line above, the Metadata will remain as HouseNumber = 30, Door = "N/A" in the database even though they're changed here.
    }

    context.People.Update(person);
    context.SaveChanges();
    return Results.Ok();
});

I am interested in knowing why this is the case. Is it intentional that I have to mark the address as modified so that EF Core can include it in its UPDATE SQL statement or is it a bug where it does not track changes when in reality it should? Why is the .Property(u => u.Metadata).IsModified = true; line needed explicitly?

[roji]

This has been previously raised in #1228 and #1168; I just opened #3314 to give a more thorough explanation of the situation and to track doing this for DOM JSON mapping (not POCO). To summarize, consider switching to EF's ToJson() support rather than using the older-style POCO mapping with jsonb - that would fix this.

[roji]

Duplicate of #3314