Dependency injection resolving by name

Question

How can I inject different implementation of object for a specific class?

For example, in Unity, I can define two implementations of IRepository

container.RegisterType<IRepository, TestSuiteRepositor("TestSuiteRepository"); container.RegisterType<IRepository, BaseRepository>();  

and call the needed implementation

public BaselineManager([Dependency("TestSuiteRepository")]IRepository repository) 

Answer 1

In addition to @adem-caglin answer I'd like to post here some reusable code I've created for name-based registrations.

UPDATE Now it's available as nuget package.

In order to register your services you'll need to add following code to your Startup class:

        services.AddTransient<ServiceA>();         services.AddTransient<ServiceB>();         services.AddTransient<ServiceC>();         services.AddByName<IService>()             .Add<ServiceA>("key1")             .Add<ServiceB>("key2")             .Add<ServiceC>("key3")             .Build(); 

Then you can use it via IServiceByNameFactory interface:

public AccountController(IServiceByNameFactory<IService> factory) {     _service = factory.GetByName("key2"); } 

Or you can use factory registration to keep the client code clean (which I prefer)

_container.AddScoped<AccountController>(s => new AccountController(s.GetByName<IService>("key2"))); 

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Full code of the extension is in github.

Answer 2

As @Tseng pointed, there is no built-in solution for named binding. However using factory method may be helpful for your case. Example should be something like below:

Create a repository resolver:

public interface IRepositoryResolver {     IRepository GetRepositoryByName(string name); }  public class RepositoryResolver : IRepositoryResolver  {     private readonly IServiceProvider _serviceProvider;     public RepositoryResolver(IServiceProvider serviceProvider)     {         _serviceProvider = serviceProvider;     }     public IRepository GetRepositoryByName(string name)     {          if(name == "TestSuiteRepository")             return _serviceProvider.GetService<TestSuiteRepositor>();          //... other condition          else            return _serviceProvider.GetService<BaseRepositor>();     }  } 

Register needed services in ConfigureServices.cs

services.AddSingleton<IRepositoryResolver, RepositoryResolver>(); services.AddTransient<TestSuiteRepository>(); services.AddTransient<BaseRepository>();  

Finally use it in any class:

public class BaselineManager {     private readonly IRepository _repository;      public BaselineManager(IRepositoryResolver repositoryResolver)     {         _repository = repositoryResolver.GetRepositoryByName("TestSuiteRepository");     } }