Static repository... can't use DI, what to do?

Question

I am in a situation where we need to modify what is being returned from the static repository in a 3rd party open-source application (NopCommerce). The problem is that they use static repositories, so I can't merely inherit an interface and DI my own repository. I'm trying to do this without modifying the NopCommerce code-base... any fresh ideas?

Edit: I want NopCommerce to use my repos, rather than have my code use theirs.

Thanks! Josh

Answer 1

You could abstract away their stuff by creating an interface of your own and a class implementation that delegates to NopCommerce. Then have your code use the interface instead of directly accessing NopCommerce's classes. You can modify the output of NopCommerce inside your class before the result is returned to your application.

And as an added bonus you could also mock the interface to do some tests that didn't require the full-blown repository implementations.

Something like this, in code:

public interface IRepository 
{
   MyItem GetItem(int id);
}

public class MyNopCommerceWrapper : IRepository
{
   public MyItem GetItem(int id)
   {
       // I have no idea what NopCommerce API looks like, so I made this up.
       var myItem = NopCommerce.GetItem(id);

       ModifyMyItem(myItem);

       return myItem;
   }
}

Answer 2

Sounds like a job for Facade.

Answer 3

We are currently on a really, really tight deadline, and this problem was not forseen. So I am thinking of first starting with a poor man's static interface/poor man's DI like the following (so I don't have to modify the entire solution). Then at a later time, when we are not-so-pressed for time, change over to use an interface and dependency injection and submit a patch to NopCommerce:

// Poor-man's static interface (DI).
public static class OriginalBuiltInStaticClass {
    private static IMyNewClass _myNewClass;

    public static void Inject(IMyNewClass myNewClass) {
        _myNewClass = myNewClass;
        A = _myNewClass.A;
        B = _myNewClass.B;
        C = _myNewClass.C;
    }

    public static Action A = CopySimpleRenameBuiltInStaticClass.A;
    public static Func<int, string> B = CopySimpleRenameBuiltInStaticClass.B;
    public static Action C = CopySimpleRenameBuiltInStaticClass.C;
}

// Original vendor class which was copied and renamed.
public static class CopySimpleRenameBuiltInStaticClass {
    public static void A() {
        Console.WriteLine("OriginalBuiltInStaticClass.A()");
    }

    public static string B(int id) {
        Console.WriteLine("OriginalBuiltInStaticClass.B()");
        return id.ToString();
    }

    public static void C() {
        Console.WriteLine("OriginalBuiltInStaticClass.C()");
    }
}

// Creating an interface to merge into trunk of NopCommerce (convert static repositories)
public interface IMyNewClass {
    void A();
    string B(int id);
    void C();
}

// Implementation of interface.
public class MyNewClass : IMyNewClass {
    public void A() {
        Console.WriteLine("MyNewClass.A()");
    }

    public string B(int id) {
        Console.WriteLine("MyNewClass.B()");
        return id.ToString();
    }

    public void C() {
        CopySimpleRenameBuiltInStaticClass.C();
    }

}

Any thoughts?