Unity with asp.net mvc, passing parameters with property injection

Question

I am currently inserting a dependency in my mvc controller as shown below:

public class HomeController : Controller
{
    [Dependency]
    public IProxyService ProxyService { get; set; }
}

In global.asax, the type is registered using

UnityContainer _container = new UnityContainer();
_container.RegisterType<IProxyService, SystemProxyServiceEx>();

Now, I need to pass a few parameters to the SystemProxyServiceEx constructor. These include some values stored in the session variable(HttpSessionStateBase Session) that are stored during authentication. How do I make this happen?

Why don't you use constructor injection in your HomeController? This way you can remove the dependency on the Unity container from within your application. — Steven
– Steven, Commented May 11, 2011 at 12:54

Rocklan · Accepted Answer · 2018-05-18 02:52:31Z

2

The common thing to do is to wrap those in a class and inject it based on an interface. For instance:

// This interface lives in a service or base project.
public interface IUserContext
{
    string UserId { get; }

    // Other properties
}

// This class lives in your Web App project 
public class AspNetUserContext : IUserContext
{
    public string UserId
    {
        get { return (int)HttpContext.Current.Session["Id"]; }
    }

    // Other properties
}

Now you can make your SystemProxyServiceEx take a dependency on IUserContext. Last step is to register it, which of course will be easy:

_container.RegisterType<IUserContext, AspNetUserContext>();

edited May 18, 2018 at 2:52

Rocklan

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answered May 11, 2011 at 12:29

Steven

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2 Comments

user748526 Over a year ago

thanks! i tried this but there is still a problem. Some of the session variables such as loggedinuser,etc are actually initialized in my account controller that performs the authentication. The _container.RegisterType called is currently in the Application_Start() event of global.asax so the problem i get it when unity tries to resolve the dependency right at the start,in the AspNetUserContext class, the HttpContext.Current.Session is null at this point. Is there any way i can do a delay load here so that this call is made after the authentication has been done.

Steven Over a year ago

@user748526: Unity will not call the properties on the AspNetUserContext class, so as long as you don't use the properties when the user is not authenticated, there should not be a problem. You could even add a IsUserAuthenticated property.

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