使用BinaryFormatter序列化复杂对象

Question

I am trying to serialize a complex object which contains 2 lists of complex objects using the code below

public static byte[] SerializeObject(object obj)
{
    BinaryFormatter formatter = new BinaryFormatter();
    MemoryStream stream = new MemoryStream();
    formatter.Serialize(stream, obj);
    return stream.ToArray();
}

When I deserialize though I get NHibernate exceptions that my list objects failed to initialize, so I suspect that they haven't been serialized correctly in the first place. The error I receive is failure to lazily initialize a collection of some object, no session or session was closed.

But if they were properly serialized then there would not be a need to lazily initialize, they would already be there, right?

Answer 1

What may be happening here is that you are serializing NHibernate proxies for the collections. Depending on your mapping, for performance reasons, NHibernate will not load a collection up until the point you explicitly access its elements.
It's also able to do this for associations of various kinds (it's called 'lazy loading') and the way it works is that NHibernate actually instantiates and uses a proxy object that implements the correct interface (or derives from your classes in case of other associations).

You may already know all that, but I'm explaining it for context in case you don't. If you need to know more about lazy loading check out this article: http://nhibernate.info/doc/howto/various/lazy-loading-eager-loading.html

In this case, NHibernate may be using a proxy for your lists and as the BinaryFormatter is accessing them in a non-conventional way that is what you end up serializing.

If this is the case, there are many ways in which you could go ahead and fix it and they depend on how you are structuring your project.

A quick way to confirm if this takes care of your issues is, before serializing your object go ahead and initialize its lazy properties (note that you need to do this for each one or recursively as the Initialize method will only load data for the proxy you give to it):

NHibernateUtil.Initialize(yourObject);
NHibernateUtil.Initialize(yourObject.List1);
NHibernateUtil.Initialize(yourObject.OtherList);
...etc...
SerializeObject(yourObject);