unity ResolveAll 泛型接口

Question

我正在使用 Unity IoC，我想注册非通用 class 到通用接口的映射。之后，我想使用 ResolveAll 方法来检索与通用接口关联的所有注册。这是示例代码：

interface ISample<out T> { }
class Ca : ISample<int> { }
class Cb : ISample<string> { }

class Program
{
    static void Main(string[] args)
    {

        var container = new UnityContainer();
        container.RegisterType<ISample<int>,Ca>();
        container.RegisterType<ISample<string>, Cb>();

        var classList = container.ResolveAll(typeof(ISample<>));
    }
}

在我的代码中这一行：

var classList = container.ResolveAll(typeof(ISample<>));

出现此错误：

Resolution of the dependency failed, type = "ConsoleApplication1Unity.ISample`1[T][]", name = "(none)". Exception occurred while: while resolving. Exception is: InvalidOperationException - Could not execute the method because either the method itself or the containing type is not fully instantiated.
----------------------------------------------- At the time of the exception, the container was:
  Resolving ConsoleApplication1Unity.ISample`1[T][],(none)

Answer 1

ISample<> 不是 Unity 的有效类型；您无法注册它，也无法使用 ResolveAll 来获取所有使用它的类型。如果您查看 ResolveAll returns，这有助于说明问题。在这种情况下，它将 return 一个无效的 IEnumerable>。

我不太确定你想做什么，所以我不知道推荐尝试什么。

Answer 2

ResolveAll 用于查找特定类型的所有命名解析，它不适用于您正在使用的开放泛型。要得到你想要的，你需要做

var registrations = container.Registrations
                   .Where(x => x.RegisteredType.IsGenericType && 
                               x.RegisteredType.GetGenericTypeDefinition() == typeof(ISample<>))
                   .ToList();

这将为您提供所有注册的列表。要获取 class 对象的集合，您只需在每次返回的注册时调用 Resolve。

var classList = new List<object>();
foreach (var registration in registrations)
{
    var classObject = container.Resolve(registration.RegisteredType, registration.Name);
    classList.Add(classObject);
}

唯一可以同时容纳 ISample<int> 和 ISample<string> 的 List<T> 类型是 object。 List<ISample<object>> 是行不通的。如果您将界面重写为

interface ISample { }
interface ISample<out T> : ISample { }

它使代码更简单，并且您在列表中得到一个更好的对象，它可以让您访问不依赖于 T.[=25 的 ISample 的属性和方法=]

var registrations = container.Registrations
                   .Where(x => typeof(ISample).IsAssignableFrom(x.RegisteredType));

var classList = new List<ISample>();
foreach (var registration in registrations)
{
    var classObject = container.Resolve(registration.RegisteredType, registration.Name);
    classList.Add((ISample)classObject);
}

P.S. 只是为了弄清楚内置的 ResolveAll 在做什么，它基本上是

public IEnumerable<object> ResolveAll(Type t, params ResolverOverride[] resolverOverrides)
{
    var registrations = this.Registrations.Where(x => x.RegisteredType == t);
    foreach (var registration in registrations)
    {
        if(registration.Name != null)
            yield return this.Resolve(registration.RegisteredType, registration.Name, resolverOverrides)
    }
}

Answer 3

我已经完成创建以下 ExtensionMethod 的任务

public static IEnumerable<object> ResolveAllOpenGeneric(this IUnityContainer container, Type openGenericType)
{
    if (!openGenericType.IsGenericTypeDefinition)
        throw new ArgumentNullException("argument must be open generic type");

    return container.Registrations.Where(c =>
                                            c.RegisteredType.IsGenericType
                                            && c.RegisteredType.GetGenericTypeDefinition() == openGenericType
                                        )
                                        .Select(r =>
                                                    container.Resolve(r.RegisteredType, r.Name)
                                        );
}

public static IEnumerable<T> ResolveAllOpenGeneric<T>(this IUnityContainer container, Type openGenericType)
{
    if (!openGenericType.IsGenericTypeDefinition)
        throw new ArgumentNullException("argument must be open generic type");

    return container.Registrations.Where(c =>
                                             c.RegisteredType.IsGenericType
                                             && c.RegisteredType.GetGenericTypeDefinition() == openGenericType
                                         )
                                         .Select(r =>
                                                     (T)container.Resolve(r.RegisteredType, r.Name)
                                         );
}

unity ResolveAll 泛型接口

Unity ResolveAll Generics Interface

c#

generics

ioc-container

unity-container