Question

This should be simple, but I’m getting confused.

I have a parent/child tables – and all I want to do, is select from the parent table, depending on filtering of the child table.

So the parent table, Rooms, is linked one to many to the clients table – I want to select rooms, where there are no linked records in the Clients table, where the clients.Departure date is before a specific date:

  public class Room
    {
        public int RoomId { get; set; }
        public string RoomName { get; set; }
        public List<Client> Clients { get; set; }
    }

  public class Client
    {
        public int ClientId { get; set; }
        public int RoomId { get; set; }
        public string Name { get; set; }
        public DateTime Arrival { get; set; }
        public DateTime Departure { get; set; }
        public Room Room { get; set; }
    }

In my controller I have been trying:

 public ActionResult Avail()
        {
            DateTime dteFrom = DateTime.Parse("2012-07-01");  //hard coded for testing
            Room room = db.Rooms.Where(r => r.Clients.Any(c => c.Departure <= dteFrom));

But I get the error message:

Cannot implicitly convert type 'System.Linq.IQueryable<ttp.Models.Room>' to 'ttp.Models.Room'. An explicit conversion exists (are you missing a cast?)

Can anyone suggest do I need to change my model classes, or my Where statement?

Answer 1

Room room represents a single room whereas db.Rooms.Where(r => r.Clients.Any(c => c.Departure <= dteFrom)) returns a list of rooms.

If you expect your query will only return one result, you could do the following:

Room room = db.Rooms.SingleOrDefault(r => r.Clients.Any(c => c.Departure <= dteFrom));

Or if you would like to return all the rooms that match the query, you could do the following:

IQueryable<Room> rooms = db.Rooms.Where(r => r.Clients.Any(c => c.Departure <= dteFrom));