I’ve been using StructureMap 2.5x for some time, and I have been quite pleased with it. I’d read a bit about 2.6x, and the improvements to the registry DSL seemed cool but not quite cool enough to give me the motivation I needed to make upgrading the version used in my project a priority.

A week or two ago, I found what proved to be my compelling reason. It’s a method called

ObjectFactory.ReleaseAndDisposeAllHttpScopedObjects();

And it does just what it says it does. This could really help in one particular situation encountered in my application (using StructureMap for NHibernate session management in a web context). I need to cache the session factory as a singleton, but the sessions themselves should be unique per request. Before coming across this method I was using a filter to clean up sessions at the end of the request:

public class SessionPerRequest : ActionFilterAttribute
{
	public override void OnActionExecuted (ActionExecutedContext filterContext)
	{
		// for when session doesn't need to remain open for view rendering
		//StructureMap.ObjectFactory.GetInstance<NHibernate.ISession>().Dispose();
	}

	public override void OnResultExecuted (ResultExecutedContext filterContext)
	{
		StructureMap.ObjectFactory.GetInstance<NHibernate.ISession>().Dispose();
	}
}

This was working fine, but I did need to decorate every controller method where I wanted to apply it. In addition to not really being my idea of a good time, this leaves the door open for me to forget to decorate a method somwhere, causing the app to leak sessions all over the place. Also, if I put it someplace it’s not needed, a session will be created only to be disposed of!

So today, I finally got around to upgrading. I made the slight improvements to Registry code that were now possible, but I was most excited to get rid of the filter above, and replace it with this method (in Global.asax.cs):

protected void Application_EndRequest()
{
    ObjectFactory.ReleaseAndDisposeAllHttpScopedObjects();
}

While there was certainly some pain involved in removing the filter I had used previously, this approach will make my life much easier in the long run. I already trust StructureMap to cache these different instances for me correctly, why not trust it to clean up afterwards as well? It’s also nice to know that if I end up needing any other objects to be unique per http context, I won’t need to write any more code to clean up after myself. This is a great feature added to the library, and I wish I’d read about it sooner!

EDIT: I saw a thread today mentioning another method called

HttpContextBuildPolicy.DisposeAndClearAll();

that’s been available since StructureMap 2.3.5 that seems to do the exact same thing. So I didn’t really need to upgrade after all, but I guess its nice to stay current. I don’t want to make excuses for my ignorance, but I’ve gotta say accessing it through the ObjectFactory makes a bit more sense to me. In a way I’m more impressed that it showed up there, because its’ often a harder decision to relocate code when refactoring than to add it in the first place!