How to register multiple implementations of the same interface in Asp.Net Core?

Question

I have services that are derived from the same interface.

public interface IService { }
public class ServiceA : IService { }
public class ServiceB : IService         


        

Answer 1

I have run into the same problem and I worked with a simple extension to allow Named services. You can find it here:

• https://www.nuget.org/packages/Subgurim.Microsoft.Extensions.DependencyInjection.Named/
• https://github.com/subgurim/Microsoft.Extensions.DependencyInjection.Named

It allows you to add as many (named) services as you want like this:

 var serviceCollection = new ServiceCollection();
 serviceCollection.Add(typeof(IMyService), typeof(MyServiceA), "A", ServiceLifetime.Transient);
 serviceCollection.Add(typeof(IMyService), typeof(MyServiceB), "B", ServiceLifetime.Transient);

 var serviceProvider = serviceCollection.BuildServiceProvider();

 var myServiceA = serviceProvider.GetService("A");
 var myServiceB = serviceProvider.GetService("B");

The library also allows you to easy implement a "factory pattern" like this:

    [Test]
    public void FactoryPatternTest()
    {
        var serviceCollection = new ServiceCollection();
        serviceCollection.Add(typeof(IMyService), typeof(MyServiceA), MyEnum.A.GetName(), ServiceLifetime.Transient);
        serviceCollection.Add(typeof(IMyService), typeof(MyServiceB), MyEnum.B.GetName(), ServiceLifetime.Transient);

        serviceCollection.AddTransient();

        var serviceProvider = serviceCollection.BuildServiceProvider();

        var factoryPatternResolver = serviceProvider.GetService();

        var myServiceA = factoryPatternResolver.Resolve(MyEnum.A);
        Assert.NotNull(myServiceA);
        Assert.IsInstanceOf(myServiceA);

        var myServiceB = factoryPatternResolver.Resolve(MyEnum.B);
        Assert.NotNull(myServiceB);
        Assert.IsInstanceOf(myServiceB);
    }

    public interface IMyServiceFactoryPatternResolver : IFactoryPatternResolver
    {
    }

    public class MyServiceFactoryPatternResolver : FactoryPatternResolver, IMyServiceFactoryPatternResolver
    {
        public MyServiceFactoryPatternResolver(IServiceProvider serviceProvider)
        : base(serviceProvider)
        {
        }
    }

    public enum MyEnum
    {
        A = 1,
        B = 2
    }

Hope it helps