Deleting a list of objects

[TheShihan]

Hi, I try to delete a list of objects (all reservations for a given user). I've got problems with iterating the list, here's my code so far:

    public void DeleteReservationsByUserId(int userId)
    {
        using (AppEntities context = new AppEntities())
        {
            var reservations = from u in context.Users.Include("Reservations")
                               where u.UserId == userId
                               select u.Reservations;

            foreach (Reservation res in reservations.ToList())
            {
                context.DeleteObject(res);
            }

            context.SaveChanges();
        }
    }

The problem lies in the "foreach (Reservation res in reservations)" part.. it throws an exception, tell me that it cannot convert from one type to another.. but I don't understand, normally I can directly cast to eg. "IList" with ToList(). But normally I don't user a navigation property, so maybe they behave different than "normal" results? Any ideas? Shi

[Adam Maras]

Here's your problem:

var reservations = from u in context.Users.Include("Reservations")
where u.UserId == userId
select u.Reservations;

The Reservations members in your User object is actually a collection of entities; what your select clause actually creates is an IQueryable<EntitySet<Reservation>> collection, not an IQueryable<Reservation> like you would expect. If you're trying to aggregate/concatenate the Reservations collections from multiple User objects, you need to look into using LINQ's Enumerable.SelectMany[^] extension method.

[TheShihan]

Ok, that was it. Thank you! For more information see: http://weblogs.asp.net/zeeshanhirani/archive/2008/03/26/select-many-operator-part-1.aspx[^]