用于属性注入的DryIOC容器配置

Question

我搜索了一个简单的示例，说明如何将DryIoc容器配置为将依赖项简单地注入属性，就像它注入构造函数args一样。

鉴于下面的工作示例..。

货柜登记：

    public static void Register(HttpConfiguration config)
    {
        var c = new Container().WithWebApi(config);

        c.Register<IWidgetService, WidgetService>(Reuse.Singleton);
        c.Register<IWidgetRepository, WidgetRepository>(Reuse.Singleton);
    }

小部件服务：

public class WidgetService : IWidgetService
{
    private readonly IWidgetRepository _widgetRepository;

    public WidgetService(IWidgetRepository widgetRepository)
    {
        _widgetRepository = widgetRepository;
    }

    public IList<Widget> GetWidgets()
    {
        return _widgetRepository.GetWidgets().ToList();
    }
}

小部件库：

public class WidgetRepository : IWidgetRepository
{
    private readonly IList<Widget> _widgets;

    public WidgetRepository()
    {
        _widgets = new List<Widget>
        {
            new Widget {Name = "Widget 1", Cost = new decimal(1.99), Description = "The first widget"},
            new Widget {Name = "Widget 2", Cost = new decimal(2.99), Description = "The second widget"}
        };
    }

    public IEnumerable<Widget> GetWidgets()
    {
        return _widgets.AsEnumerable();
    }
}

配置需要如何更改才能支持像这样的WidgetService，其中DryIoc将把WidgetRepository作为属性注入？

所需的Widget服务：

public class WidgetService : IWidgetService
{
    public IWidgetRepository WidgetRepository { get; set; }

    public IList<Widget> GetWidgets()
    {
        return WidgetRepository.GetWidgets().ToList();
    }
}

失败尝试

我尝试过这些配置更改，但它们似乎对在WidgetService上启用属性注入没有任何影响。

附录1：

public static void Register(HttpConfiguration config)
    {
        var c = new Container().WithWebApi(config);

        // Seems logical - no luck
        c.InjectPropertiesAndFields(PropertiesAndFields.Auto);

        c.Register<IWidgetService, WidgetService>(Reuse.Singleton);
        c.Register<IWidgetRepository, WidgetRepository>(Reuse.Singleton);
    }

附录2：

    public static void Register(HttpConfiguration config)
    {
        var c = new Container(Rules.Default.With(propertiesAndFields: PropertiesAndFields.Auto))
                    .WithWebApi(config);

        c.Register<IWidgetService, WidgetService>(Reuse.Singleton);
        c.Register<IWidgetRepository, WidgetRepository>(Reuse.Singleton);
    }

我也尝试了上面的PropertiesAndFields.All，也没有运气。

注意:我知道属性注入不是推荐的方法，构造函数注入是首选的原因很多。然而，我想知道如何正确地做这两件事。

更新

按照@dadhi的建议，我将尝试#2更改为初始化容器如下：

var c = new Container(Rules.Default.With(propertiesAndFields: PropertiesAndFields.All(withNonPublic: false,
                                                            withPrimitive: false,
                                                            withFields: false,
                                                            ifUnresolved: IfUnresolved.Throw)))
.WithWebApi(config);

但后来我收到了这个错误：

{
    "Message" : "An error has occurred.",
    "ExceptionMessage" : "An error occurred when trying to create a controller of type 'WidgetController'. Make sure that the controller has a parameterless public constructor.",
    "ExceptionType" : "System.InvalidOperationException",
    "StackTrace" : "   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n   at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
    "InnerException" : {
        "Message" : "An error has occurred.",
        "ExceptionMessage" : "Type 'IOCContainerTest.DryIOC.Controllers.WidgetController' does not have a default constructor",
        "ExceptionType" : "System.ArgumentException",
        "StackTrace" : "   at System.Linq.Expressions.Expression.New(Type type)\r\n   at System.Web.Http.Internal.TypeActivator.Create[TBase](Type instanceType)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)"
    }
}

DryIoc现在似乎试图通过使用我没有的无arg构造函数来初始化WidgetController。我假设由于规则更改为PropertiesAndFields.All(...)，DryIoc试图对所有注册项使用属性注入。

public class WidgetController : ApiController
{
    private readonly IWidgetService _widgetService;

    public WidgetController(IWidgetService widgetService)
    {
        _widgetService = widgetService;
    }

    // GET api/<controller>
    public List<WidgetSummary> Get()
    {
        return _widgetService.GetWidgetSummaries();
    }
}

我试图使用属性注入初始化WidgetService (如上文所示)，但WidgetController使用构造函数注入。也许我不能兼而有之，但我在想，PropertiesAndFields.Auto规则会允许两者兼而有之。我还将WidgetController更改为属性注入的设置。然后，我从DryIoc中没有异常，但是WidgetService在WidgetController中以null结尾。这是更新的WidgetController。

public class WidgetController : ApiController
{
    public IWidgetService WidgetService { get; set; }

    // GET api/<controller>
    public List<WidgetSummary> Get()
    {
        return WidgetService.GetWidgetSummaries();
    }
}

自动属性注入似乎仍然难以捉摸。

更新2

经过多次尝试和错误(以及@dadhi的建议)，我决定在我的WidgetController中使用构造函数注入，并在注册其他服务时指定属性注入。这允许迁移代码，这些代码现在就将属性注入用于构造函数注入，但控制器除外。以下是我更新的集装箱注册：

    public static void Register(HttpConfiguration config)
    {
        var c = new Container(Rules.Default).WithWebApi(config);

        var autoInjectProps = Made.Of(propertiesAndFields: PropertiesAndFields.Auto);

        c.Register<IWidgetService, WidgetService>(Reuse.Singleton, autoInjectProps);
        c.Register<IWidgetRepository, WidgetRepository>(Reuse.Singleton, autoInjectProps);
    }

我很想最终找出适用于控制器和其他服务的黄金环境，但他们的行为似乎有所不同。但是，就目前而言，这是一个足够可行的解决方案。

更新3

根据@dadhi的建议更新容器配置如下，以便将所有东西(包括WidgetController)连接为属性注入：

    public static void Register(HttpConfiguration config)
    {
        var c = new Container(Rules.Default.With(propertiesAndFields: PropertiesAndFields.All(withNonPublic: false, withPrimitive: false, withFields: false, ifUnresolved: IfUnresolved.Throw)))
                    .WithWebApi(config, throwIfUnresolved: type => type.IsController());

        c.Register<IWidgetService, WidgetService>(Reuse.Singleton);
        c.Register<IWidgetRepository, WidgetRepository>(Reuse.Singleton);
    }

这似乎至少产生了一个有意义的异常，并解释了为什么当我设置容器使用PropertiesAndFields.All(..)时控制器被不同对待。

{
    "Message" : "An error has occurred.",
    "ExceptionMessage" : "An error occurred when trying to create a controller of type 'WidgetController'. Make sure that the controller has a parameterless public constructor.",
    "ExceptionType" : "System.InvalidOperationException",
    "StackTrace" : "   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n   at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
    "InnerException" : {
        "Message" : "An error has occurred.",
        "ExceptionMessage" : "Unable to resolve HttpConfiguration as property \"Configuration\"\r\n  in IOCContainerTest.DryIOC.Controllers.WidgetController.\r\nWhere no service registrations found\r\n  and number of Rules.FallbackContainers: 0\r\n  and number of Rules.UnknownServiceResolvers: 0",
        "ExceptionType" : "DryIoc.ContainerException",
        "StackTrace" : "   at DryIoc.Throw.It(Int32 error, Object arg0, Object arg1, Object arg2, Object arg3)\r\n   at DryIoc.Container.ThrowUnableToResolve(Request request)\r\n   at DryIoc.Container.DryIoc.IContainer.ResolveFactory(Request request)\r\n   at DryIoc.ReflectionFactory.InitPropertiesAndFields(NewExpression newServiceExpr, Request request)\r\n   at DryIoc.ReflectionFactory.CreateExpressionOrDefault(Request request)\r\n   at DryIoc.Factory.GetExpressionOrDefault(Request request)\r\n   at DryIoc.Factory.GetDelegateOrDefault(Request request)\r\n   at DryIoc.Container.ResolveAndCacheDefaultDelegate(Type serviceType, Boolean ifUnresolvedReturnDefault, IScope scope)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)"
    }
}

Answer 1

第一次会议应改为：

public static void Register(HttpConfiguration config)
{
    var c = new Container().WithWebApi(config);

    c.Register<IWidgetService, WidgetService>(Reuse.Singleton);
    c.Register<IWidgetRepository, WidgetRepository>(Reuse.Singleton);

    // Resolve service first then inject properties into it.
    var ws = c.Resolve<IWidgetService>();
    c.InjectPropertiesAndFields(ws);
}

来自代码的第二次尝试应该是有效的，但可能是另外一种情况。要找到答案，您可以将规则更改为：

PropertiesAndFields.All(withNonPublic: false, withPrimitives: false, withFields: false, ifUnresolved: IfUnresolved.Throw)

不过，更好的选择是为精确服务指定确切的属性：

c.Register<IWidgetService, WidgetService>(Reuse.Singleton, 
     made: PropertiesAndFields.Of.Name("WidgetRepository"));

或强类型：

c.Register<IWidgetService, WidgetService>(
    Made.Of(() => new WidgetService { WidgetRepository = Arg.Of<IWidgetRepository>() }),
    Reuse.Singleton);

更新：

DryIoc的缺省值为“最小惊喜”：类型为DI的单个构造函数，且不使用属性注入。但是，您可以选择--在默认值中简化迁移：

IContainer c = new Container(Rules.Default.With(
    FactoryMethod.ConstructorWithResolvableArguments, 
    propertiesAndFields: PropertiesAndFilds.Auto);

可能对你的案子来说已经足够了。

如果没有，您可以添加规则：

    .WithFactorySelector(Rules.SelectLastRegisteredFactory())
    .WithTrackingDisposableTransients()
    .WithAutoConcreteTypeResolution()

更新2：

这个测试对我有效。

[Test]
public void Controller_with_property_injection()
{
    var config = new HttpConfiguration();
    var c = new Container()
        .With(rules => rules.With(propertiesAndFields: PropertiesAndFields.Auto))
        .WithWebApi(config, throwIfUnresolved: type => type.IsController());

    c.Register<A>(Reuse.Singleton);

    using (var scope = config.DependencyResolver.BeginScope())
    {
        var propController = (PropController)scope.GetService(typeof(PropController));
        Assert.IsNotNull(propController.A);
    }
}

public class PropController : ApiController
{
    public A A { get; set; }
}

public class A {}

但是将PropertiesAndFields.Auto改为

PropertiesAndFields.All(false, false, false, IfUnresolved.Throw)从更新3中产生了错误。

更新3：

谢谢你上传样品回购，它帮助发现了问题。

DryIoc PropertiesAndFields.Auto规则将注入所有声明的和基类的属性，这将导致基类中定义的某些属性的错误。好的是，Auto只是一个预定义的规则，您可以定义自己的规则来排除基类属性：

private static IEnumerable<PropertyOrFieldServiceInfo> DeclaredPublicProperties(Request request)
{
    return (request.ImplementationType ?? request.ServiceType).GetTypeInfo()
        .DeclaredProperties.Where(p => p.IsInjectable())
        .Select(PropertyOrFieldServiceInfo.Of);
}

然后像这样创建容器：

var c = new Container()
    .With(rules => rules.With(propertiesAndFields: DeclaredPublicProperties))
    .WithWebApi(config, throwIfUnresolved: type => type.IsController());

我已经提交了带有补丁的按下。

BTW在未来/下一个DryIoc版本中，我将提供该API以简化基本或仅声明属性选择。

Answer 2

好吧，忽略我最后的评论，可能与此无关。查看异常堆栈跟踪，WebAPI似乎回到了使用Activator.CreateInstance作为控制器，这是因为DryIoc无法解决它。但退路掩盖了实际的DryIoc错误。要找到它，请尝试：

container.WithWebApi(throwIfUnresolved: type => type.IsController());