I've read the Armen Shimoon's article ASP.NET Core: Factory Pattern Dependency Injection and I've decided to solve my ASP.NET Core DI problem using the technique suggested by him. I've got a generic interface:
public interface IItemRepository<out T> where T : BaseItem
and its generic implementation:
public class ItemRepository<T> : IItemRepository<T> where T : BaseItem
I register it with:
services.AddSingleton(typeof(IItemRepository<>), typeof(ItemRepository<>));
But for Currency I've got a specific implementation:
public class CurrencyRepository : ItemRepository<Currency>
(Curency is of the BaseItem type.) What I want is to register
CurrencyRepository
for
IItemRepository<Currency>
and
ItemRepository<T>
for all other items that implement BaseItem . I created a factory class to accomplish this:
public class ItemRepositoryFactory : IServiceFactory> where T : BaseItem
{
private readonly ApplicationDbContext _context;
public ItemRepositoryFactory(ApplicationDbContext context)
{
_context = context;
}
public ItemRepository Build()
{
if (typeof(T) == typeof(Currency))
return new CurrencyRepository(_context) as ItemRepository;
return new ItemRepository(_context);
}
}
but I don't know how to register it with IServiceCollection . Or maybe I'm not on the right way at all?
You can't register it explicitly. ASP.NET Core DI is meant to be simple and offer out of box DI/IoC experience and easy for other DI/IoC containers to plugin.
So the built-in IoC doesn't offer Auto-Registrations, Assembly scanning, Decorators or registration of all interfaces/sub types of the class.
For concrete implementations, there is a "workaround"
services.AddScoped<IMyService,MyService>();
services.AddScoped<MyService>(provider => provider.GetService<IMyService>());
Then both MyService
and IMyService
inside a constructor would receive the same instance of the class.
But this doesn't work with open generics and is a manuell process. For automatic discovery or registration you need a 3rd party IoC container, such as Autofac, StructureMap etc.
But in your concrete sample it should be enough to register IItemRepository<Currency>
inside your ConfigureServices
method
services.AddScoped<IItemRepository<Currency>,CurrencyRepository>();
But actually the open generic should cover this case already, if you inject IItemRepository<Currency>
into your services.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.