Use Ninject to bind legacy types

Question

I have a legacy application that I want to modify to use Ninject to reduce coupling.

I have a number of classes in the data layer that share a base type:

public abstract class BaseData { }

public class Child1Data : BaseData { }

public class Child2Data : BaseData { }

I also have a number of classes that use/manage these:

public abstract class BaseManager { }
public class Child1Manager : BaseManager { }
public class Child2Manager : BaseManager { }

I have to create a function that maps one to another:

BaseManager GetManager(BaseData dataObject)
{
    //Want to use Ninject to do this
    if (dataObject is Child1Data)
       return new Child1Manager(dataObject);
    //...etc
}

I created a NinjectModule with the following bindings:

Bind<BaseManager>().To<Child1Manager>.Named(typeof(Child1Data).FullName);

Then in my GetManager() function I can do:

BaseManager GetManager(BaseData dataObject)
{
    return ServiceLocator.Get<BaseManager>(dataObject.GetType().FullName);
}

Is there an easier and more proper way to bind service to specific type?

I can modify children of BaseManager, but unfortunately I have to preserve BaseData and the signature of GetManager() function.

Thank you in advance for your ideas and suggestions. This is my first exposure to Ninject and dependency injection.

Jan Muncinsky Jan Muncinsky · Accepted Answer · 2017-08-16T13:37:35

You can achieve this with a factory:

public interface IManagerFactory
{
    BaseManager GetManager(BaseData dataObject);
}


public class UseFirstArgumentTypeAsNameInstanceProvider : StandardInstanceProvider
{
    protected override string GetName(System.Reflection.MethodInfo methodInfo, object[] arguments)
    {
        return arguments[0].GetType().FullName;
    }
}

Bind<IManagerFactory>().ToFactory(() => new UseFirstArgumentTypeAsNameInstanceProvider());
Bind<BaseManager>().To<Child1Manager>().Named(typeof(Child1Data).FullName);
Bind<BaseManager>().To<Child2Manager>().Named(typeof(Child2Data).FullName);

Then inject your IManagerFactory where you want.

Use Ninject to bind legacy types

1 Answers