A complex ActiveRecord find through a lot of models.. I think there must be a better way to do it

Rails test

@operadores = User.find(:all, :conditions => 
    { :id => 
        EventoTrabajosUser.find(:all, :conditions =>
        {    :evento_trabajo_id =>  
                EventoTrabajo.find(:all, :conditions => 
                    { :evento_id =>  @planificacion.eventos.collect{ |b| b.id }  } 
                ).collect { |c| c.id }
        }).collect { |d| d.user_id }
    })