Unity - Inject an object to Constructor by calling a Method of a Class

Question

I have the following interface and its implementation

public class DummyProxy : IDummyProxy
{
    public string SessionID { get; set; }
    public DummyProxy(string sessionId)
    {
        SessionId = sessionId;
    }
}

public interface IDummyProxy
{
}

Then I have another class to get a session id

public class DummySession
{
    public string GetSessionId()
    {
        Random random = new Random();
        return random.Next(0, 100).ToString();
    }
}

Now, in my Unity container, I would like to inject 'session id' to DummyProxy every time the container is trying to resolve IDummyProxy. But this 'session id' must be generated from DummySession class.

container.RegisterType<IDummyProxy, DummyProxy>(
    new InjectionConstructor(new DummySession().GetSessionId()));

Is this even possible?

Lukazoid · Accepted Answer · 2014-07-27 21:59:47Z

7

Your best approach for this would be to make use of an InjectionFactory, i.e.

container.RegisterType<IDummyProxy, DummyProxy>(new InjectionFactory(c => 
{
    var session = c.Resolve<DummySession>() // Ideally this would be IDummySession
    var sessionId = session.GetSessionId();

    return new DummyProxy(sessionId);
}));

An InjectionFactory allows you to execute additional code when creating the instance.

The c is the IUnityContainer being used to perform the resolve, we use this to resolve the session and then obtain the session id, from that you can then create your DummyProxy instance.

edited Jul 27, 2014 at 21:59

answered Jul 27, 2014 at 21:34

Lukazoid

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1 Comment

stack247 Over a year ago

Nice.. this is exactly what I want to do. Thanks!

Cameron · Accepted Answer · 2014-07-26 01:37:37Z

0

You can do this. It's possible. It will only create the Session Id once (which is what I'd assume you'd want to do.)

I would personally rather give the DummyProxy a dependency on the DummySession (or better yet, an abstraction like IDummyProxy) and make it call DummySession.GetSessionID().

answered Jul 26, 2014 at 1:37

Cameron

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2 Comments

stack247 Over a year ago

Well, I actually need the SessionId be called every time, so each resolve for DummyProxy will have new SessionId.

stack247 Over a year ago

I could modify DummyProxy to depend on IDummySession, but I thought there might be a simpler way to do this..

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