Autofac：使用Web API 2进行设置

Question

我正在一个隔离的C＃解决方案中测试Autofac，我想向家庭控制器中注入一个测试管理器，其设置如下：

一个非常简单的界面

public interface ITestManager
{
    IEnumerable<string> Get();
}

实施者

public class TestManager : ITestManager
{
    public IEnumerable<string> Get()
    {
        return new List<string>
        {
            "Lorem ipsum dolor sit amet, consectetur adipiscing elit, ",
            "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. ",
            "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut ",
            "aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in ",
            "voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint ",
            "occaecat cupidatat non proident, sunt in culpa qui officia ",
            "deserunt mollit anim id est laborum."
        };
    }
}

这将由TestController接收

public class TestController : Controller
{
    private ITestManager TestManager { get; set; }

    public TestController(ITestManager testManager)
    {
        TestManager = testManager;
    }
}

这样就建立了依赖关系

public static class Autofac
{
    public static void Register(HttpConfiguration config)
    {
        // Base set-up
        var builder = new ContainerBuilder();

        // Register your Web API controllers.
        builder.RegisterApiControllers(Assembly.GetExecutingAssembly());

        // OPTIONAL: Register the Autofac filter provider.
        builder.RegisterWebApiFilterProvider(config);

        // Register dependencies

        SetUpRegistration(builder);

        // Build registration.
        var container = builder.Build();

        // Set the dependency resolver to be Autofac.
        config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
    }

    private static void SetUpRegistration(ContainerBuilder builder)
    {
        builder.RegisterType<TestManager>()
            .As<ITestManager>()
            .InstancePerLifetimeScope();
    }
}

这是从global.asax内部链接的

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    GlobalConfiguration.Configure(WebApiConfig.Register);
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    BundleConfig.RegisterBundles(BundleTable.Bundles);

    IoC.Autofac.Register(GlobalConfiguration.Configuration);
}

运行此命令将导致以下错误：

“ /”应用程序中的服务器错误。

没有为此对象定义无参数构造函数。

说明：执行当前Web请求期间发生未处理的异常。 请查看堆栈跟踪，以获取有关错误及其在代码中起源的更多信息。

异常详细信息：System.MissingMethodException：没有为此对象定义无参数构造函数。

我想念什么？

完整堆栈跟踪：

堆栈跟踪

[MissingMethodException: No parameterless constructor defined for this object.]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +119
   System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +232
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +83
   System.Activator.CreateInstance(Type type) +11
   System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +55

[InvalidOperationException: An error occurred when trying to create a controller of type 'AutofacWebApi.Controllers.HomeController'. Make sure that the controller has a parameterless public constructor.]
   System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +178
   System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +76
   System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +88
   System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +191
   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +50
   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +48
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +16
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +103
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

Answer 1

很简单，我从HomeController复制了控制器类信息，该信息是Controller类型，而不是ApiController类型！

所以正确的实现是这样的：

public class TestController : ApiController
{
    private ITestManager TestManager { get; set; }

    public TestController(ITestManager testManager)
    {
        TestManager = testManager;
    }

    // GET: api/Test
    public IEnumerable<string> Get()
    {
        return this.TestManager.Get();
    }
}

我正在使用builder.RegisterApiControllers(Assembly.GetExecutingAssembly())注册控制器，但这仅适用于API控制器，并且由于我的TestController属于Controller类型（这是MVC的核心控制器类型），因此未进行接线正确起来。

如果您还希望使用（普通的）MVC，则应使用以下代码：

builder.RegisterControllers(Assembly.GetExecutingAssembly())

荣誉对沃尔玛指着我在正确的方向。