Question

我经过长时间的努力搜寻，却发现没有任何帮助。我哪里错了？我真的不知道该怎么办。我在下面写了所有细节。我尝试过但没有成功。

尝试创建类型的控制器时发生错误 'TypeNewsController'。确保控制器有一个无参数公共构造函数。

 public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            WebApiConfig.Register(GlobalConfiguration.Configuration);
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
            Bootstrapper.Run();
        }
    }

我的apicontroller：

public class TypeNewsController : ApiController
    {
        private readonly ITypeNewsService _typeNewsService;

        public TypeNewsController(ITypeNewsService typeNewsService)
        {
            _typeNewsService = typeNewsService;
        }
        [HttpGet]
        public TypeNewsResponse Get([ModelBinder] PageRequest model)
        {
            model = model ?? new PageRequest();
            var output = _typeNewsService.GetTypeNewss().ToList();
            return new TypeNewsResponse
            {
                Page = model.PageIndex,
                Records = model.PageSize,
                Rows = output.ToList(),
                Total = output.Count() / model.PageSize,
            };
        }
    }

错误：

<Error>
<Message>An error has occurred.</Message>
<ExceptionMessage>
An error occurred when trying to create a controller of type 'TypeNewsController'. Make sure that the controller has a parameterless public constructor.
</ExceptionMessage>
<ExceptionType>System.InvalidOperationException</ExceptionType>
<StackTrace>
at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType) at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request) at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncCore(HttpRequestMessage request, CancellationToken cancellationToken) at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__0.MoveNext()
</StackTrace>
<InnerException>
<Message>An error has occurred.</Message>
<ExceptionMessage>
Type 'JuventusNewsSiteApk.Controllers.TypeNewsController' does not have a default constructor
</ExceptionMessage>
<ExceptionType>System.ArgumentException</ExceptionType>
<StackTrace>
at System.Linq.Expressions.Expression.New(Type type) at System.Web.Http.Internal.TypeActivator.Create[TBase](Type instanceType) at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator) at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)
</StackTrace>
</InnerException>
</Error>

Bootstrapper类：

public static class Bootstrapper
    {
        public static void Run()
        {
            SetAutofacContainer();
            //Configure AutoMapper
            AutoMapperConfiguration.Configure();
        }

        private static void SetAutofacContainer()
        {
            var builder = new ContainerBuilder();
            builder.RegisterControllers(Assembly.GetExecutingAssembly());
            builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
            builder.RegisterType<UnitOfWork>().As<IUnitOfWork>().InstancePerRequest();
            builder.RegisterType<DatabaseFactory>().As<IDatabaseFactory>().InstancePerRequest();
            builder.RegisterAssemblyTypes(typeof(NewsRepository).Assembly)
                .Where(t => t.Name.EndsWith("Repository"))
                .AsImplementedInterfaces().InstancePerRequest();
            builder.RegisterAssemblyTypes(typeof(NewsService).Assembly)
                .Where(t => t.Name.EndsWith("Service"))
                .AsImplementedInterfaces().InstancePerRequest();

            builder.RegisterAssemblyTypes(typeof(DefaultFormsAuthentication).Assembly)
                .Where(t => t.Name.EndsWith("Authentication"))
                .AsImplementedInterfaces().InstancePerRequest();

            builder.Register(
                c => new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(new JuventusNewsApkEntities())))
                .As<UserManager<ApplicationUser>>().InstancePerRequest();

            builder.RegisterFilterProvider();
            IContainer container = builder.Build();
            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
        }
    }

更新：

 public class TypeNewsService : ITypeNewsService
    {
        private readonly ITypeNewsRepository _typeNewsRepository;
        private readonly IUnitOfWork _unitOfWork;
        public TypeNewsService(ITypeNewsRepository typeNewsRepository,
            IUnitOfWork unitOfWork)
        {
            _typeNewsRepository = typeNewsRepository;
            _unitOfWork = unitOfWork;
        }

        #region ITypeNewsService Member

        public void AddTypeNews(TypeNews typeNews)
        {
            _typeNewsRepository.Add(typeNews);
            SaveTypeNews();
        }

        public void DeleteTypeNews(int id)
        {
            _typeNewsRepository.DeleteById(id);
            SaveTypeNews();
        }

        public IEnumerable<TypeNews> GetTypeNewss()
        {
            var output = _typeNewsRepository.GetAll();
            return output;
        }

        public void SaveTypeNews()
        {
            _unitOfWork.Commit();
        }

        #endregion

    }

    public interface ITypeNewsService
    {
        void AddTypeNews(TypeNews typeNews);
        void DeleteTypeNews(int id);
        IEnumerable<TypeNews> GetTypeNewss();
        void SaveTypeNews();
    }

Answer 1

您的控制器是WebApi控制器，Autofac的注册与MVC注册不同。 WebApi不使用DependencyResolver，因此您需要告诉WebApi专门使用Autofac解析器。

您需要将其添加到SetAutofacContainer代码中：

// Create the depenedency resolver.
var resolver = new AutofacWebApiDependencyResolver(container);

// Configure Web API with the dependency resolver.
GlobalConfiguration.Configuration.DependencyResolver = resolver;

有关详细信息，请参阅https://code.google.com/p/autofac/wiki/WebApiIntegration。

Answer 2

在我的情况下，原因是解析器无法找到映射。也就是说，假设HomeController依赖于IDumb，解析器无法找到实现IDumb的Dumb的具体实现。

换句话说错误信息

**No parameterless constructor defined for this object
An error occurred when trying to create a controller of type 'ToDoListT1.WebApp.Controllers.HomeController'. Make sure that the controller has a parameterless public constructor**

完全是误导。

在我的情况下，我刚刚通过添加对Dumb类的项目的引用来解决。应该是＆＃34;没有找到IDumb的映射。＆＃34;。我不确定问题是否与NInject或MS有关。无论如何，我花了几个小时才找到它。

Answer 3

请确保您使用相同的通话类型，我的意思是Get，Post，Put以及您在控制器方法中使用的类型。

您是否需要为控制器添加有效的存储库到NijectConfig.cs。

kernel.Bind的百分比抑制率iRepo] GT;（）到＆lt; [回购] GT;（）InRequestScope（）;

Answer 4

对于控制器，您应该使用参数较少的构造函数。如果您想使用参数化构造函数，请使用如下代码。

传递Type NewsService类的对象

private readonly ITypeNewsService _typeNewsService;
public TypeNewsController():this(new TypeNewsService ())
{
} 
public TypeNewsController(ITypeNewsService typeNewsService)
{
   _typeNewsService = typeNewsService;
}

尝试创建“TypeNewsController”类型的控制器时发生错误

4 个答案: