在EF中，通过删除子行克隆中首先引用它的子行来删除父行是否有效？

Question

        public void Delete(Dinner dinner)
        {
            List<RSVP> rsvps = dinner.RSVPs.ToList();// This clone looks inefficient.

            foreach (RSVP rsvp in rsvps)
                entities.RSVPs.DeleteObject(rsvp);

            entities.Dinners.DeleteObject(dinner);
        }

QUESTION:

Deleting a parent row by deleting the child rows referencing it first through the child row clones looks inefficient.

Duplicating the child rows will consume huge resources I think.

If so, what is the better way?

EDIT 1:

namespace NerdDinner.Models
{
    public class DinnerRepository
    {
        private NerdDinnerEntities entities = new NerdDinnerEntities();

        public IQueryable<Dinner> FindAllDinners()
        {
            return entities.Dinners;
        }

        public IQueryable<Dinner> FindUpcomingDinners()
        {
            return from dinner in entities.Dinners
                   where dinner.EventDate > DateTime.Now
                   orderby dinner.EventDate
                   select dinner;
        }

        public Dinner GetDinnerByID(int DinnerID)
        {
            return entities.Dinners.FirstOrDefault(d => d.DinnerID == DinnerID);
        }

        public void Add(Dinner dinner)
        {
            entities.Dinners.AddObject(dinner);
        }

        public void Delete(Dinner dinner)
        {
            //List<RSVP> rsvps = dinner.RSVPs.ToList();

            //foreach (RSVP rsvp in dinner.RSVPs)
            //    entities.RSVPs.DeleteObject(rsvp);

            entities.Dinners.DeleteObject(dinner);
        }

        public void Save()
        {
            entities.SaveChanges();
        }
    }
}

Answer 1

Set the delete rule to cascade on the foreign key, then when you delete the dinner object the database will automatically remove all child records.

Keep in mind, this probably won't be reflected down to EF so any objects already in memory will not be marked as deleted.