Fetching lazy loaded component causes n + 1 query when querying a subclass abstraction #3289
Description
I've found that when doing a LINQ query and fetching a component it seems to work fine when querying a class, but if I try to query the interface the class implements then the fetch doesn't appear to work.
For example say I have the following:
public class Entity : IEntity
{
public virtual int Id { get; set;
public virtual string Name { get; set; }
public virtual Component Component { get; set; }
}
public class SubEntity : Entity, ISubEntity
{
public virtual bool SomeProperty { get; set; }
}
public class Component
{
public virtual string Field { get; set; }
}
public interface IEntity
{
int Id { get; set; }
string Name { get; set; }
Component Component { get; set; }
}
public interface ISubEntity : IEntity
{
public bool SomeProperty { get; set; }
}Which is mapped like so:
protected override HbmMapping GetMappings()
{
var mapper = new ModelMapper();
mapper.Class<Entity>(rc =>
{
rc.Id(x => x.Id, m => m.Generator(Generators.Identity));
rc.Property(x => x.Name);
rc.Component(x => x.Component);
});
mapper.JoinedSubclass<SubEntity>(rc =>
{
rc.EntityName(typeof(ISubEntity).FullName);
rc.Key(k => k.Column("Id"));
rc.Property(x => x.SomeProperty);
});
mapper.Component<Component>(rc =>
{
rc.Property(x => x.Field);
rc.Lazy(true);
});
return mapper.CompileMappingForAllExplicitlyAddedEntities();
}Now if I was to say the following, the database would be hit once:
var result = session.Query<SubEntity>()
.Fetch(e => e.Component)
.ToList();
// Make sure the component field is executed.
foreach (var entity in result)
{
var foo = entity.Component?.Field;
}However if I say the following, the database would be hit for each entity in the result:
var result = session.Query<ISubEntity>()
.Fetch(e => e.Component)
.ToList();
// Make sure the component field is executed.
foreach (var entity in result)
{
var foo = entity.Component?.Field;
}Edit: See below for a test case.