Unity Application Block, How pass a parameter to Injection Factory?

Question

Here what I have now

  Container.RegisterType<IUserManager, UserManagerMock>();
  Container.RegisterType<IUser, UserMock>(
                new InjectionFactory(
                    (c) => c.Resolve<IUserManager>().GetUser("John")));

and get it

Container.Resolve<IProfile>();

I want to pass a name as parameter to Factory so that I will be able to resolve user object with name; Something like this:

 Container.Resolve<IProfile>("Jonh");

How can I change the type registration for this case?

Answer 1

While most DI frameworks have advanced features to do these types of registrations, I personally rather change the design of my application to solve such a problem. This keeps my DI configuration simple and makes the code easier to understand. Especially for the creation of objects that depend on some context (thread, request, whatever) or have a lifetime that must be managed explicitly, I like to define factories. Factories make these things much more explicit.

In your situation, you want to fetch a profile for a certain user. This is typically something you would like to have a factory for. Here's an example of this:

// Definition
public interface IProfileFactory
{
    IProfile CreateProfileForUser(string username);
}

// Usage
var profile = Container.Resolve<IProfileFactory>()
    .CreateProfileForUser("John");

// Registration
Container.RegisterType<IProfileFactory, ProfileFactory>();

// Mock implementation
public class ProfileFactory : IProfileFactory
{
    public IProfile CreateProfileForUser(string username)
    {
        IUser user = Container.Resolve<IUserManager>()
            .GetUser(username);

        return new UserProfile(user);
    }
}

I hope this helps.