Question

I build a model as below. The relationship between Recycler and Account is 1:1.

public class MyContext : DbContext
{
    public DbSet<Quoter> Quoters { get; set; }
    public DbSet<Account> Accounts { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Account>()
            .HasRequired(a => a.RecyclerRef)
            .WithRequiredDependent(r => r.AccountRef);
    }
}

public class Quoter
{
    public int QuoterId { get; set; }
    public string Text { get; set; }

}

public class Recycler : Quoter
{
    public string Description { get; set; }
    public virtual Account AccountRef { get; set; }
}

public class Account
{
    public int AccountId { get; set; }
    public Recycler RecyclerRef { get; set; }
}

But, I get exceptions when I do the either of these queries:

var query1 = context.Quoters
    .OfType<Recycler>()
    .Include(r => r.AccountRef)
    .Where(r => r.QuoterId == 1)
    .ToList();

var query2 = context.Set<Recycler>()
    .Include(r => r.AccountRef)
    .Where(r => r.QuoterId == 1)
    .ToList();

Exception shows that ResultType is “Transient.reference[POCOFirst.Quoter]”，but recommanded is “Transient.reference[POCOFirst.Recycler]”

If I remove the ToList(), it works well. But I need a list as the return value of method.

Why can’t I do ToList()? Thanks

Answer 1

It looks like you have stumble upon this bug in EF. Another reference to the bug.

Workaround would be to remove the Include method.