统一接口，多工厂

Question

所以问题是我何时声明：

[Dependency]
public AuthenticationService _authenticationServices { get; set; }

_authenticationServices 将一直保持 null。它未被引用，这将引发 Null Reference Exception。我假设问题源于我的 Unity 配置文件：

container.RegisterType<ICrudFactory, ZNodeDataContextFactory>();
container.RegisterType<ICrudFactory, MincronDataContextFactory>();

因为它们都使用相同的接口，但是有一个单独的具体实现。实现如下：

public interface ICrud : IDisposable
{
     // Method's to be exposed, via general repository.
}

public interface ICrudFactory
{
     ICrud Create();
}

public ZNodeDataContext : DbContext, ICrud
{
     // Concrete implementation.
}

public MincronDataContext : DbContext, ICrud
{
     // Concrete implementation.
}

public ZNodeDataContextFactory : ICrudFactory
{
     ICrud ICrudFactory.Create()
     {
           return ZNodeDataContext();
     }
}

public MincronDataContextFactory : ICrudFactory
{
     ICrud ICrudFactory.Create()
     {
           return MincronDataContext();
     }
}

public class AuthenticationService
{
     private readonly ICrudFactory _factory;
     public AuthenticationService(ICrudFactory factory)
     {
         _factory = factory;
     }

     public void Sample()
     {
          using(var context = _factory.Create())
              context.Method(...);
     }
}

我想保留该结构，以避免代码重复。

Answer 1

您要将 ZNodeDataContextFactory 注入 AuthenticationService 吗？注入的一点是服务现在不应该与实现有关。但是如果你真的想要一个特定的实现，你可以创建一个命名实例。

public class AuthenticationService
{
     private readonly ICrudFactory _factory;
     public AuthenticationService([Dependency("ZNodeData")] ICrudFactory factory)
     {
         _factory = factory;
     }
}

并且在您的配置中：

container.RegisterType<ICrudFactory, ZNodeDataContextFactory>("ZNodeData");
container.RegisterType<ICrudFactory, MincronDataContextFactory>("MincronData");

或者：

    public class AuthenticationService
    {
         private readonly IEnumerable<ICrudFactory> _factories;
         public AuthenticationService(ICrudFactory[] factories)
         {
             // Now you got both...
             _factories = factories;
             var zNodeFactory = _factories.FirstOrDefault(x => x.Factory == ZNode);
         }
    }


    public interface ICrudFactory
    {
         ICrud Create();
         // Something to identify the type of data. Maybe an enum?
         FactoryType Factory {get;}
    }

public ZNodeDataContextFactory : ICrudFactory
{
     ICrud ICrudFactory.Create()
     {
           return ZNodeDataContext();
     }

     FactoryType ICrudFactory.Factory
     {
        {get {return FactoryType.ZNode;}
     }
}

Answer 2

我最终通过为每个通用存储库创建特定容器解决了这个问题。

public interface IZNodeContextFactory : ICrudFactory
{

}

public interface IMincronContextFactory : ICrudFactory
{

}

通过这种方式，我可以简单地做到：

container.RegisterType<IZNodeContextFactory, ZNodeContextFactory>();
container.RegisterType<IMincronContextFactory, MincronContextFactory>();

这允许自动依赖项解析器工作和实施，因为它们现在具有唯一的名称。

统一接口，多工厂

Unity with the same interface, multiple factories

c#

asp.net

dependency-injection

ioc-container

unity-container