Expression could not be translated for one specific entity type

[ajcvickers]

Moved from discussion #22162

Question

From @andrejohansson

I have a set of entities, whom all fulfill an interface IOwnedEntity

    public interface IOwnedEntity
    {
        BookingSupplier Owner { get; set; }
    }

These entities get a query filter applied to them:

 builder.HasQueryFilter(x => this.UserContext.OwnedBookingSuppliers.Contains(x.Owner.Id));

This filter works well with about 60 different entities, except for one entity: Rule, when retrieving this entity I get the exception:

The LINQ expression 'DbSet<Rule>\r\n    .Where(r => __ef_filter__OwnedBookingSuppliers_1\r\n        .Contains(r.Owner.Id))' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information

I am wondering what is different with this entity that causes it not being able to evaluate the query server side since it´s a fairly simple query?

I am guessing that it is the fact that Rule is an abstract base class for a set of other entities that inherits Rule. In the modelbuilder I have no special configuration for Rule but there is configurations for descendants that look like this:

            modelBuilder.Entity<CompositeRule>()
                .HasOne(p => p.Owner)
                .WithMany(p => p.OwnedCompositeRules)
                .OnDelete(DeleteBehavior.NoAction);

Relevant parts of rule:

    public abstract class Rule : BaseEntity, IRule, IOwnedEntity
    {
        [Required] public virtual BookingSupplier Owner { get; set; }
        public Guid? BookingSupplierOwnerId { get; set; }

       /// ...
}

A class referencing rules can look like this:

    public class ServiceArticle :
        OwnedEntity,
        IUserModifyableEntity,
        IRulable<ServiceTranslation>
    {
        public virtual List<Rule> Rules { get; set; }

       /// ...
  }

Does anybody know the cause? or can anybody give me hints on how to debug this so that I can learn why it´s failing to translate?

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Replies

From @smitpatel

Can you share a stand-alone repro?

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From @ajcvickers

@smitpatel Based on this:

I am guessing that it is the fact that Rule is an abstract base class for a set of other entities that inherits Rule. In the modelbuilder I have no special configuration for Rule but there is configurations for descendants that look like this:

I'm guessing that Rule is an unmapped base type. Would this explain what is being seen?

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From @smitpatel

r.Owner.Id seems to not getting expanded. My guess is r.Owner navigation is not getting expanded.

About not being mapped - There is DbSet in expression tree which comes from UserContext.OwnedBookingSuppliers means there is some DbSet. Plus, CompositeRule is in the model and a collection navigation property of Rules. Not sure if Rule is unmapped. But I could not create a runnable code based on pieces here.

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From @andrejohansson

Managed to get this to work, but the error threw me of a bit. I had made two errrors:

1. The latest migration contained a small, but significant change to the table. Preventing null from the owner relation
2. My table contained null values (since they were previously allowed)
   Once I fixed these things worked out for me.