Question

Using Castle.Windsor in ASP.NET MVC (3.0) is there any way I can appropriately handle if one of my dependencies resolves null? For instance, say I have a IMembershipService.

class ServiceInstaller
{
 // ... 
 void Install( // .. )
 { 
  container.Register(
  Component
  .For<IMembershipService>()
  .ImplementedBy<MembershipService>()
  .LifeStyle.PerWebRequest
  );
 }
}

Okay, this works great. Now, perhaps not all of my site requires a user to be logged in. Let’s assume that maybe my web host’s database server crashes for a few hours. In that event, things that looked into the database, or tried to call on my ISession might return null.

What can I do in this case? I can write if(membershipService == null) a hundred times over, but that seems pretty dumb. Is there a built-in solution to say “Hey, if we have an error, do this..?”

Answer 1

I think that the service should never be null. If the database is down, the service should be returned nevertheless, but its methods should throw an exception, return null or some default value, depending on the semantic of the service.