NHibernate，代理和平等

Question

I'm using NHibernate 3.3.1 and found very interesting problem. In my domain model I defined two classes: Carriage and CarriageRequest, referencing each other. Because lazy loading is turned on, when I access carriage.CarriageRequest - it points to a proxy object. That is okay. But when I invoke any method, defined in CarriageRequest class, 'this' references to a third object instance.

Example:

class CarriageRequest
{
  public virtual void Test(CarriageRequest instance)
  {
    Debug.WriteLine(Object.ReferenceEquals(this, instance)); // prints FALSE
  }
}

class Carriage
{ 
  public virtual CarriageRequest CarriageRequest { get; set; }
}

...
var carriage = session.Get<Carriage>(123);
carriage.CarriageRequest.Test(carriage.CarriageRequest);

So it looks like NHibernate proxies wrap original objects and forward all method invocations to wrapped objects. How can I use "==" in this case? I need to do something like this:

var shipment = (from sh in Carriage.Shipments where sh.CarriageRequest == this & sh.Warehouse == waybill.Warehouse select sh).FirstOrDefault();

This code is executed inside proxied object, so 'shipment' is always null, because 'sh.CarriageRequest == this' is always false. Because sh.CarriageRequest is a proxy, and this is a wrapped original instance.

Answer 1

Okay, NHibernate guarantees reference equality for loaded objects within the same session. And if using lazy-loading, it wraps real object with a proxy and every method invocation on a proxy is forwarded to the wrapped object. So, inside this object every reference comparison between 'this' and the same object, loaded from session, will fail (because it will be a different, proxy, object).

So, the only way to resolve this issue is to use Equals method or compare by primary keys.