Collection on an inherited class is not included

[heyadamhey]

I have a class called BonusMatch that inherits from an abstract class called Bonus. When I save a BonusMatch entity, Detached.Mappers will see the Composition collections on Bonus but not see the collection on the BonusMatch class.

The Bonus class uses an enum Discriminator.

The entity is:

public abstract class Bonus
{
....
	private IList<BonusAlert> _alerts;
        public virtual IList<BonusAlert> Alerts
        {
            get { return _alerts; }
            set { _alerts = value; }
        }
...

}

public partial class BonusMatch : Bonus
{
...
	private IList<BonusMatchTier> _tiers;
        public virtual IList<BonusMatchTier> Tiers
		{
			get { return _tiers; }
			set { _tiers = value; }
		}
...
}

My EF mapping is

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
            modelBuilder.ApplyConfiguration(new Configurations.BonusConfiguration());
            modelBuilder.Entity<BonusMatch>()
				.HasMany(b => b.Tiers)
				.WithOne(t => t.Bonus)
				.HasConstraintName("FK_BonusMatchTier_Bonus")
				.OnDelete(DeleteBehavior.Cascade);
}

...

public void Configure(EntityTypeBuilder<Bonus> modelBuilder)
{
            modelBuilder.ToTable("Bonus");
            modelBuilder.HasDiscriminator(d => d.SecondaryBonusType)
				.HasValue<BonusMatch>(BonusTypes.Match)
				.HasValue<BonusNoDeposit>(BonusTypes.NoDeposit)
				.HasValue<BonusFreeplay>(BonusTypes.Freeplay)
				.HasValue<BonusPostWager>(BonusTypes.PostWager)
				.HasValue<BonusCashback>(BonusTypes.Cashback)
				.HasValue<BonusSportsbookCashback>(BonusTypes.SportsbookCashback)
				.HasValue<BonusSportsbookFreeBet>(BonusTypes.SportsbookFreeBet)
				.HasValue<BonusSportsbookMatch>(BonusTypes.SportsbookMatch);

            modelBuilder
                .HasMany(b => b.Alerts)
                .WithOne()
                .HasConstraintName("FK_BonusAlert_Bonus")
                .OnDelete(DeleteBehavior.Cascade);
}

My Detached.Mappers configuration is as follows:

                        profileOptions.Type<Bonus>() // Not sure if this block is necessary
                            .Abstract(true)
                            .Discriminator(b => b.SecondaryBonusType)
                            .HasValue<BonusMatch>(BonusTypes.Match)
                            .HasValue<BonusNoDeposit>(BonusTypes.NoDeposit)
                            .HasValue<BonusFreeplay>(BonusTypes.Freeplay)
                            .HasValue<BonusPostWager>(BonusTypes.PostWager)
                            .HasValue<BonusCashback>(BonusTypes.Cashback)
                            .HasValue<BonusSportsbookCashback>(BonusTypes.SportsbookCashback)
                            .HasValue<BonusSportsbookFreeBet>(BonusTypes.SportsbookFreeBet)
                            .HasValue<BonusSportsbookMatch>(BonusTypes.SportsbookMatch);

                        profileOptions.Type<Bonus>()
				.Member(b => b.DateUpdated).Exclude()
                            .Member(b => b.DateAdded).Exclude()
                            .Member(b => b.Guid).Exclude()
                            .Member(b => b.Casino).Parent()
                            .Member(b => b.SpecificCountries).Aggregation()
                            .Member(b => b.ProhibitedCountries).Aggregation()
                            .Member(b => b.SpecificWebsiteClients).Aggregation()
                            .Member(b => b.AllowedUSStates).Aggregation()
                            .Member(b => b.SpecificUSStates).Aggregation()
                            .Member(b => b.BonusCasinoCurrencies).Composition()
                            .Member(b => b.Alerts).Composition()
                            .Member(b => b.TrackerLinks).Composition()
                            .Member(b => b.GameEligibilities).Composition()
                            .Member(b => b.BonusSignificantTerms).Composition();
							
                        // This composition appears to be ignored
                        profileOptions.Type<BonusMatch>()
                            .Member(b => b.Tiers).Composition();

When I save a BonusMatch and call _context.Map<TDomainEntity>(dto); (where TDomainEntity is a BonusMatch) I step through the Detached.Mappers code until I reach the Load method in the Loader class. The query.Load gets all of the collections on Bonus (e.g. Alerts ) but it does not generate a query to return the Tiers collection on BonusMatch so the Tiers collection is empty in the target object below:

var target = Loader.Load(dbContext, typeof(TEntity), entityOrDto);

As a result, EF's change tracker always sees the Tiers items as Added and not Unchanged or Modified

Screenshots
DTO object has two Tiers

Loaded object has no Tiers. No SQL query is generated to select them

Expected behavior
I expected the Composition attribute on Tiers would include the collection from the database for the change tracking, but it is not I suspect this is due to the inheritance in some way.
This configuration appears to be ignored

Desktop (please complete the following information):

• OS: Windows 11
• Browser: Chrome
• Version: 135

[leonardoporro]

Hi @heyadamhey !
Sorry for the delay ... I'm starting a new job, and trying to handle normal life issues!
At a first glance, if the base properties work and the inherited ones does't it could be because the class is boxed and the mapper factory selected is for the base class. Maybe if you try to pass it as object, the mapper picks the right factory.
I'll build a solution using the code and config you provided but i don't have time to do that before next Wednesday. I'm sorry, Will come back with more info.

[heyadamhey]

Thanks for getting back to me @leonardoporro .
I'm not quite sure what you mean by "pass it as object" but I'm happy to wait until you have time.

I really appreciate you taking the time to put some code together for me

[heyadamhey]

I found the solution to be the following:
Remove the configuration for the base object Bonus and have a full configuration for each derived type e.g.

Remove this code:

                        profileOptions.Type<Bonus>() // Not sure if this block is necessary. Removing it made no apparent difference
                            .Abstract(true)
                            .Discriminator(b => b.SecondaryBonusType)
                            .HasValue<BonusMatch>(BonusTypes.Match)
                            .HasValue<BonusNoDeposit>(BonusTypes.NoDeposit)
                            .HasValue<BonusFreeplay>(BonusTypes.Freeplay)
                            .HasValue<BonusPostWager>(BonusTypes.PostWager)
                            .HasValue<BonusCashback>(BonusTypes.Cashback)
                            .HasValue<BonusSportsbookCashback>(BonusTypes.SportsbookCashback)
                            .HasValue<BonusSportsbookFreeBet>(BonusTypes.SportsbookFreeBet)
                            .HasValue<BonusSportsbookMatch>(BonusTypes.SportsbookMatch);

                        profileOptions.Type<Bonus>()
				.Member(b => b.DateUpdated).Exclude()
                            .Member(b => b.DateAdded).Exclude()
                            .Member(b => b.Guid).Exclude()
                            .Member(b => b.Casino).Parent()
                            .Member(b => b.SpecificCountries).Aggregation()
                            .Member(b => b.ProhibitedCountries).Aggregation()
                            .Member(b => b.SpecificWebsiteClients).Aggregation()
                            .Member(b => b.AllowedUSStates).Aggregation()
                            .Member(b => b.SpecificUSStates).Aggregation()
                            .Member(b => b.BonusCasinoCurrencies).Composition()
                            .Member(b => b.Alerts).Composition()
                            .Member(b => b.TrackerLinks).Composition()
                            .Member(b => b.GameEligibilities).Composition()
                            .Member(b => b.BonusSignificantTerms).Composition();

                        profileOptions.Type<BonusMatch>()
                            .Member(b => b.Tiers).Composition();

New config:

profileOptions.Type<BonusMatch>()
	.Member(b => b.DateAdded).Exclude()
	.Member(b => b.Guid).Exclude()
	.Member(b => b.Casino).Exclude()
	.Member(b => b.SpecificCountries).Aggregation()
	.Member(b => b.ProhibitedCountries).Aggregation()
	.Member(b => b.SpecificWebsiteClients).Aggregation()
	.Member(b => b.AllowedUSStates).Aggregation()
	.Member(b => b.SpecificUSStates).Aggregation()
	.Member(b => b.BonusCasinoCurrencies).Composition()
	.Member(b => b.Alerts).Composition()
	.Member(b => b.TrackerLinks).Composition()
	.Member(b => b.GameEligibilities).Composition()
	.Member(b => b.Tiers).Composition();

profileOptions.Type<BonusMatchTier>()
    .Member(b => b.Bonus).Parent()
    .Member(b => b.FreeSpinsGames).Composition();

I have another object that does not have derived types and was not having this mapping issue, so it seems derived types were not being mapped correctly. Not sure whether this is a bug or incorrect configuration on my side

[leonardoporro]

@heyadamhey I'm sorry I wasn't able to help with this one, I've been away for a long time.
(Half of my family underwent a surgery and/or long hospitalization in the last 5 months, crazy)
I've seen that the library is useful, but it's incredibly hard to debug for most of the people. So I was thinking about moving it to a source generator, something similar to https://github.com/riok/mapperly.
So you'll be able to inspect the source code before even running the app, override specific mapping parts and/or creating your own templates.
For the first version I think I won't be able to support fluent, so annotations (attributes) would be a must to simplify the job.
And won't be able to get the model automatically from the DbContext as DbContext generates it in runtime.
There are tradeoffs...

What do you think?