Deleting a list of objects

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.NET3.0

.NET3.5

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)<br />        {<br />            using (AppEntities context = new AppEntities())<br />            {<br />                var reservations = from u in context.Users.Include("Reservations")<br />                                   where u.UserId == userId<br />                                   select u.Reservations;<br /><br />                foreach (Reservation res in reservations.ToList())<br />                {<br />                    context.DeleteObject(res);<br />                }<br /><br />                context.SaveChanges();<br />            }<br />        }

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<reservation>" with ToList(). But normally I don't user a navigation property, so maybe they behave different than "normal" results?

Any ideas?

Shi

Posted 14-Jul-09 13:06pm

TheShihan

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Adam Maras · Answer 1 · 2009-07-14T14:00:00

Here's your problem:

var reservations = from u in context.Users.Include("Reservations")<br />                   where u.UserId == userId<br />                   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.