Why is one of my reference properties not being included when using LINQ to Entities Include()?

问题

I have the following property declarations and mappings (abridged classes):

public class Consumer: AuditableEntity
{
    public virtual Consumer Parent { get; set; }
    public virtual User User { get; set; }
    public virtual Role Role { get; set; }
    public virtual ICollection<Consumer> Consumers { get; set; }
}

public ConsumerMap()
{
    HasRequired(t => t.Role)
        .WithMany(t => t.Consumers)
        .Map(a => a.MapKey("RoleId"))
        .WillCascadeOnDelete(false);
    HasRequired(t => t.User)
        .WithOptional(t => t.Consumer)
        .Map(a => a.MapKey("UserId"))
        .WillCascadeOnDelete(false);
}

A manual database query confirms all joins are successful and in fact, a manual execution of the query sent by EF is successful. Yet when I use the following query, the User property on the two Consumer objects returned is null:

return CurrentDbContext.Consumers.Include("User").Include("Role").Where(e => !e.IsDeleted);

来源：https://stackoverflow.com/questions/10494086/why-is-one-of-my-reference-properties-not-being-included-when-using-linq-to-enti