Ninject constructor argument

I have this interface:

public interface IUserProfileService
{
    // stuff
}

Implemented by:

public class UserProfileService : IUserProfileService
{
    private readonly string m_userName;

    public UserProfileService(string userName)
    {
        m_userName = userName;
    }
}

I need this injected into a controller like this:

public class ProfilesController : BaseController
{
    private readonly IUserProfileService m_profileService;

    public ProfilesController(IUserProfileService profileService)
    {
        m_profileService = profileService;
    }
}

I don't know how I can register this interface and its implementation into Ninject 开发者_开发问答container so that userName param is passed in when the Ninject inits an instance of this service.

Any ideas how I can achieve this?

---

The technical ninject answer is to use constructor arguments like so:

Bind<IUserProfileService>().To<UserProfileService>().WithConstructorArgument("userName", "karl");

Of course you need to figure out where "karl" comes from. It really depends on your app. Maybe its a web app and it's on the HttpContex? I don't know. If it gets rather complicated then you might want to write a IProvider rather than doing a regular binding.

---

One alternative is to inject a factory and create your dependency using Create(string userName).

public class UserProfileServiceFactory
{
    public IUserProfileService Create(string userName)
    {
        return new UserProfileService(userName);
    }
}

It might seem off to have to create another class but the benefits mostly comes when UserProfileService takes in additional dependencies.

---

The trick is to not inject the username in that class. You call this class a service so it would probably work transparantly with multiple users. I see two solutions:

1. Inject an abstraction into the service that represents the current user:

   public class UserProfileService : IUserProfileService
   {
       private readonly IPrincipal currentUser;
   
       public UserProfileService(IPrincipal currentUser)
       {
           this.currentUser = currentUser;
       }
   
       void IUserProfileService.SomeOperation()
       {
           var user = this.currentUser;
   
           // Do some nice stuff with user
       }
   }
   

2. Create an implementation that is specific to the technology you are working with, for instance:

   public class AspNetUserProfileService : IUserProfileService
   {
       public AspNetUserProfileService()
       {
       }
   
       void IUserProfileService.SomeOperation()
       {
           var user = this.CurrentUser;
   
           // Do some nice stuff with user
       }
   
       private IPrincipal CurrentUser
       {
           get { return HttpContext.Current.User; }
       }
   }
   

If you can, go with option one.