MVC 5 / UnityConfig - Same Interface - Multiple Implementations

Question

So I have this basic Interface:

public interface ISearchable
{
    List<AutocompleteResult> Search(string term);
}

And two classes which implement this interface:

First Class:

public class LandlordReader :ISearchable
{
    public List<AutocompleteResult> Search(string term)
    {
        ....
    }
}

Second Class:

public class CityReader : ISearchable
{
    public List<AutocompleteResult> Search(string term)
    {
       ....
    }
}

From this point on, I'm in the dark... In UnityConfig.cs I tried to register them by giving them a name:

public static void RegisterTypes(IUnityContainer container)
{
    container.RegisterType<ISearchable, CityReader>("City");
    container.RegisterType<ISearchable, LandlordReader>("Landlord");
}

In the MVC Controller I have no idea on what to specify (IN THE CONSTRUCTOR) - to tell it that I want one or another:

public LandlordController(ISearchable searcher)
{
    // I want the LandlordReader here, but in the CityController, I want the CityReader....
    this.searcher = searcher;
}

I'm quite a noob, regarding DI and UnityInjector, so a full working example would be good. I got lots of advices up to this point (use generic interface, use unity factory) - but trying them myself, none worked.

I know in ASP.NET Core there's an attribute you can directly specify in the constructor's parameter list, but I am currently working in MVC5.

Thanks. Finished a long post. Phew.

Answer 1

You can try one of these options if suitable in your scenario.

1

Using Named Serivce Injection

public static void RegisterTypes(IUnityContainer container)
{
    container.RegisterType<ISearchable, CityReader>("City");
    container.RegisterType<ISearchable, LandlordReader>("Landlord");
}

public LandlordController([Dependency("Landlord")]ISearchable searcher)
{
    this.searcher = searcher;
}

2

public interface ISearchable<T> where T : class
{
//..............
}

public class LandlordReader : ISearchable<LandlordReader>
{
    public List<AutocompleteResult> Search(string term)
    {
        ....
    }
}

public class CityReader : ISearchable<CityReader>
{
    public List<AutocompleteResult> Search(string term)
    {
       ....
    }
}
public static void RegisterTypes(IUnityContainer container)
{
        container.RegisterType<ISearchable, CityReader>("City");
        container.RegisterType<ISearchable, LandlordReader>("Landlord");
}

and then when using in the constructor do this

    private readonly ISearchable<CityReader> _cityReadersearcher;
    private readonly ISearchable<LandlordReader> _landLordsearcher;
    public LandlordController(ISearchable<CityReader> cityReadersearcher, 
     ISearchable<LandlordReader> landLordsearcher)
    {
         _cityReadersearcher= _cityReadersearcher;
        _landLordsearcher = landLordsearcher;
    }