Circular References in RavenDB

Question

I'm using RavenDB with models like:

public class Cart {
    List<Item> Items = new List<Item>();
}

public class Item {
    public Cart Cart;
}

When I add an Item to a Cart, I wire up both sides of the relationship.

How does RavenDB handle serializing & deserializing this? Will the reference to Cart be assigned automatically or is there a way to manually wire it on load?

Answer 1

If you save cart you will get an exception 'Self referencing loop detected...' when you call SaveChanges().

The fix is easy. You add the [JsonObject(IsReference = true)] attribute to Cart. This tells the serializer to store Item's Cart as a reference instead of as a new object.

[JsonObject(IsReference = true)] 
public class Cart
{
    public List<Item> Items = new List<Item>();
}

public class Item
{
    public Cart Cart;
}

I also wanted to mention that it IS property deserialized. In other words, Cart is re-assigned to Item when it is loaded.

var cart = new Cart();
cart.Items.Add(new Item { Cart = cart });
session.Store(cart);
session.SaveChanges();

...

var cart = session.Query<Cart>().First();
Assert.ReferenceEquals(cart, cart.Items.First().Cart); //this works