Jul 16, 2009

What's wrong with this code(Part XI) ?

Since I joined db4o I'm actively following our forums and trying to help developers to get their questions / issues answered.

Starting with this post I want to present the most recurring topics (don't know exactly how many) in the format of "What's wrong with this code".

But before we start you may be wondering where are the other parts (since this is titled as Part XI, where are parts from I to X). Well, they do exists in the portuguese posts (titled as "O que esta errado com este código (Parte ?)") so I decided to continue with the numbering schema ;)

Ok, for this first one, take a look in the following code:
using Db4objects.Db4o;
using Db4objects.Db4o.Linq;
using System.Linq;

class Item 
{
 public string Name { get; set; }
 public Item Father { get; set ; }
}

public class Test
{
    private const string DatabaseFile = "wwwtc1.odb";
    private static void Main()
    {
        Item item1 = new Item { Name = "Adriano" };
        using (var db = Db4oEmbedded.OpenFile(DatabaseFile))
        {
           db.Store(item1);
        }
  
        using (var db = Db4oEmbedded.OpenFile(DatabaseFile))
        {
          Item item2 = new Item {Name = "Carol",  Father = item1 };
          db.Store(item2);
        }  
    }
}
If you have done some work with db4o you probably will easily spot the problem.

I'll provide the answer in a future post.

Have fun!

1 comment:

tehlike said...

Adriano will be saved twice, as the second object container doesn't know that it was already in the db.