2

我正在使用 simpleinjector 2.3.0.0 和 .net 4.5。

我一直在尝试注册一个依赖于 IEnumerable 的工厂、一个事物的实例以及一个工作单元装饰器。（除其他事项外）

这是我的工厂：

public class ThingFactory : IThingFactory
{
    private readonly IEnumerable<IThing> things;

    public ThingFactory (IEnumerable<IThing> things)
    {
        this.things= things;
    }

    public IThing GetThing(ThingType thingType)
    {
     return things.FirstOrDefault(t => t.IsApplicable(thingType));
    }
}

这是我对 IThing 的实现

 public class ThingOne: IThing
{
     private IThingFactory thingFactory;

    public ThingOne(IThingFactory thingFactory)
    {
        this.thingFactory= thingFactory;
    }

    public void Execute(MyDto myDto)
    {
       //do stuff
      //get the next approiate IThing out of the factory and execute
    }

    public bool IsApplicable(ThingType thingType)
    {
        return thingType == ThingType.ThingOne;
    }

}

我的注册是

  container.RegisterAll<IThing>(
            from tp in typeof (IThing).Assembly.GetExportedTypes()
            where !tp.IsAbstract
            where typeof (IThing).IsAssignableFrom(tp)
            select tp);

   container.Register<IThingFactory , ThingFactory>();

这工作得很好，我可以毫无例外地验证容器。但是，当我还将以下注册添加到容器时，我得到一个异常

 container.RegisterDecorator(typeof(ICommandHandler<,>),    
 typeof(UnitOfWorkDecorator<,>));

装饰器是一个 Nhibernate UnitOFWork，它管理一个 Nhibernate 事务（这并不重要）（遵循这种模式https://cuttingedge.it/blogs/steven/pivot/entry.php?id=91）

  public class UnitOfWorkDecorator<TCommand, TResult>
    : ICommandHandler<TCommand, TResult> 
    where TCommand : ICommand
{

    public UnitOfWorkDecorator(
        ICommandHandler<TCommand, TResult> decoratedCommandHandler)
    {
        this.currentSessionContextService = currentSessionContextService;
        this.decoratedCommandHandler = decoratedCommandHandler;
    }

    public void Handle(TCommand command)
    {
          //start my nhibernate transaction
          decoratedCommandHandler.Handle(command);

          //commit the transaction                       
    }

所以无论如何，当我添加装饰器时，我得到以下异常。当我打电话时

  container.Verify();

然而，当我删除装饰器注册时，一切又好了。

Topshelf v3.1.107.0, .NET Framework v4.0.30319.18052
Topshelf.Hosts.ConsoleRunHost Error: 0 : An exception occurred, System.Reflectio
n.TargetInvocationException: Exception has been thrown by the target of an invoc
ation. ---> System.InvalidOperationException: The configuration is invalid. Crea
ting the instance for type IThingManager failed. The registered delegate for t
ype IThingManager threw an exception. The registered delegate for type IThingFa
ctory threw an exception. The registered delegate for type IEnumerable<IThing> th
rew an exception. No registration for type ThingOne could be found a
nd an implicit registration could not be made.  ---> SimpleInjector.ActivationEx
ception: The registered delegate for type IThingManager threw an exception. Th
e registered delegate for type IThingFactory threw an exception. The registered d
elegate for type IEnumerable<IThing> threw an exception. No registration for type
ThingOne could be found and an implicit registration could not be m
ade.  ---> SimpleInjector.ActivationException: The registered delegate for type
IThingFactory threw an exception. The registered delegate for type IEnumerable<IThing>     
threw an exception. No registration for type ThingOne could be
found and an implicit registration could not be made.  ---> SimpleInjector.Activ
ationException: The registered delegate for type IEnumerable<IThing> threw an exc
eption. No registration for type ThingOne could be found and an impl
icit registration could not be made.  ---> SimpleInjector.ActivationException: N
o registration for type ThingOne could be found and an implicit regi
stration could not be made.

堆栈跟踪：

at SimpleInjector.Container.ThrowNotConstructableException(Type concreteType)
at SimpleInjector.Container.ThrowMissingInstanceProducerException(Type servic
eType)at SimpleInjector.Container.GetRegistration(Type serviceType, Boolean throwOn
 Failure)   at SimpleInjector.Advanced.ContainerControlledCollection`1.   
 <>c__DisplayClass1
0.<ToLazyInstanceProducer>b__f()   at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()     at     
SimpleInjector.Advanced.ContainerControlledCollection`1.<SimpleInjector.Ad
vanced.IContainerControlledCollection.GetRelationships>b__1(Lazy`1 p)
at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
at System.Linq.Enumerable.<SelectManyIterator>d__31`3.MoveNext()
at System.Linq.Enumerable.<DistinctIterator>d__81`1.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at SimpleInjector.Advanced.ContainerControlledCollection`1.SimpleInjector.Adv
anced.IContainerControlledCollection.GetRelationships()
at SimpleInjector.Extensions.Decorators.DecoratorHelpers.ContainerControlledC
ollectionRegistration.GetRelationshipsCore()
at SimpleInjector.Registration.GetRelationships()
at SimpleInjector.InstanceProducer.GetRelationships()
at SimpleInjector.Container.OnExpressionBuilt(ExpressionBuiltEventArgs e, Ins
tanceProducer instanceProducer)
at SimpleInjector.InstanceProducer.BuildExpressionInternal()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at SimpleInjector.InstanceProducer.BuildExpression()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.BuildExpression()
at SimpleInjector.Advanced.DefaultConstructorInjectionBehavior.BuildParameter
Expression(ParameterInfo parameter)
at SimpleInjector.Registration.BuildParameterExpressionFor(ParameterInfo para
meter)
at SimpleInjector.Registration.<BuildNewExpression>b__1a(<>f__AnonymousTypef`
2 <>h__TransparentIdentifier18)
at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at SimpleInjector.Registration.BuildNewExpression(Type serviceType, Type impl
ementationType)
at SimpleInjector.Registration.BuildTransientExpression[TService,TImplementat
ion]()
at SimpleInjector.Lifestyles.TransientLifestyle.TransientLifestyleRegistratio
n`2.BuildExpression()
at SimpleInjector.InstanceProducer.BuildExpressionInternal()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at SimpleInjector.InstanceProducer.BuildExpression()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.BuildExpression()
at SimpleInjector.Advanced.DefaultConstructorInjectionBehavior.BuildParameter
Expression(ParameterInfo parameter)
at SimpleInjector.Registration.BuildParameterExpressionFor(ParameterInfo para
meter)
at SimpleInjector.Registration.<BuildNewExpression>b__1a(<>f__AnonymousTypef`
2 <>h__TransparentIdentifier18)
at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at SimpleInjector.Registration.BuildNewExpression(Type serviceType, Type impl
ementationType)
at SimpleInjector.Registration.BuildTransientExpression[TService,TImplementat
ion]()
at SimpleInjector.Lifestyles.TransientLifestyle.TransientLifestyleRegistratio
n`2.BuildExpression()
at SimpleInjector.InstanceProducer.BuildExpressionInternal()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at SimpleInjector.InstanceProducer.BuildInstanceCreator(Object& createdInstan
ce)
at SimpleInjector.InstanceProducer.GetInstance()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.GetInstance()
at SimpleInjector.InstanceProducer.Verify()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.Verify()
at SimpleInjector.Container.VerifyProducers(InstanceProducer[] producersToVer
ify)
at SimpleInjector.Container.ValidateRegistrations()
at SimpleInjector.Container.Verify()

谢谢你的帮助

编辑 - ThingManager 是入口点，如下所示：

   public class ThingManager : IThingManager
{
    private readonly IThingFactory thingFactory;

    public ThingManager(IThingFactory thingFactory)
    {
        this.thingFactory = thingFactory;
    }

    public void Run(MyDto myDto)
    {
        var firstThing = thingFactory.GetThing(ThingType.ThingOne);
        firstThing.Execute(myDto);
    }
}
4

1 回答 1

2

问题是由代码中的循环引用引起的：ThingFactory取决于IEnumerable<IThing>，取决于ThingOne，取决于ThingFactory，关闭循环。

不幸的是，由于Simple Injector 2.3 中的一个错误，描述循环引用的真正错误被隐藏了，并且抛出了一个表达性较差（在这种情况下甚至不正确）的消息。此错误已在Simple Injector 2.3.5中得到修复。

尽管循环引用存在于您的代码库中，但该Verify方法仅在注册装饰器时才会注意到此错误。内部ContainerControlledCollection<T>导致注册的元素被预编译，这允许InstanceProducer实例注意到循环。如果没有ContainerControlledCollection<T>集合，则更懒惰地评估该集合，这完全隐藏了此错误，即使在解析类型时也是如此。但是，您设计中的这种怪癖可能仍会在以后引起各种麻烦。

对于即将到来的 Simple Injector 2.4，ContainerControlledCollection<T>实际上会更懒惰地在Verify()未被调用的情况下提高性能（这对于具有深层对象图和具有许多项目的集合的应用程序是有意义的），但这意味着即使使用装饰器，验证器不会抛出异常。

Simple Injector 2.4 不抛出异常的行为实际上是正确的（并且 2.3 和 2.3.5 抛出异常的事实可以被认为是一个错误），因为 Simple Injector 的目标是在构建对象图时防止 stackoverflow 异常（当GetInstance叫做）。由于使用 an 后类型的创建被延迟IEnumerable<T>（解析 anIEnumerable<T>不会解析实例；仅迭代集合会），因此没有 stackoverflow 异常。

尽管在您的代码中使用循环引用可能是一种代码异味，但在您的代码中，它可能只会导致代码中的递归（但没有堆栈溢出），这可能是预期的行为。

您仍然可能需要重新考虑设计，因为递归深度为 10（假设您有 10 个东西并调用工厂以获取列表中的下一个东西），这将触发 55 个东西的创建（10x 第一个元素，9x第二个元素，8x 第三，... 1x 第十），这可能不是您所期望的。

于 2013-09-21T16:44:12.843 回答