How to specify constructor value on resolved concrete type using Unity IoC?

Question

I've seen a lot of posts asking about which overloaded constructor to select using Unity, but my question is a little different and I can't figure out the answer. I have the following class inheriting an Interface (partial code):

public class UnitOfWork : IUnitOfWork
{
    private DbContext _context;

    public UnitOfWork(DbContext context)
    {
        _context = context;
    }

}

So now I'm trying to use unity to resolve the concrete type to the interface like below:

container.RegisterType<IUnitOfWork, UnitOfWork>();

However, I need to pass in my Entity Framework context to that concrete type upon being resolved. I want to do something like this:

container.RegisterType<IUnitOfWork, UnitOfWork(new AdventureWorks2008R2Entities())>();

Of course I know the code above is incorrect, and have read about using the InjectionConstructor class, but I don't think that's applicable here.

So my question is, how do I define the value of that constructor on the UnitOfWork class when resolving the concrete type using Unity IoC?

Thanks!

Nick Nick · Accepted Answer · 2013-01-19T00:52:53

You need to add a registration for a DbContext: container.RegisterType<DbContext, AdventureWorks2008R2Entities>();

Remember, one major feature of an IoC container is to auto-wire. You don't need to tell each registration what instance to use. You just register interfaces/classes to implementations and let it put stuff in the right place (and override in the ideally rare occasions where you're doing something abnormal).

How to specify constructor value on resolved concrete type using Unity IoC?

2 Answers