c# - MVC 4 Web Api Controller 没有默认构造函数？

Question

这是痕迹:

<Error>
   <Message>An error has occurred.</Message>

   <ExceptionMessage>
      Type 'ProjectName.Web.Api.Controllers.ContinentsController' 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>
</Error>

我觉得这很奇怪 public class UsersController : ApiController { ... }工作正常。我比较了两个 Controller ，所有设置和结构都相似。

我正在使用 Ninject我的系统设置类似于 Jamie Kurtz Asp.Net Mvc 4 and the Web Api: Building a REST Service from Start to Finish .

从堆栈跟踪中，是否有人能够发现问题以及如何解决？谢谢!

根据要求。

大陆 Controller

[LoggingNHibernateSession]
public class ContinentsController : ApiController
{
    private readonly ISession _session;
    private readonly IContinentMapper _continentMapper;
    private readonly IHttpContinentFetcher _httpContinentFetcher;
    private readonly IDateTime _dateTime;

    public ContinentsController(ISession session, IContinentMapper continentMapper, IHttpContinentFetcher continentFetcher, IDateTime dateTime)
    {
        _session = session;
        _continentMapper = continentMapper;
        _httpContinentFetcher = continentFetcher;
        _dateTime = dateTime;
    }

    public IEnumerable<Continent> Get()
    {
        var continents = _session
            .Query<Data.Model.Continent>()
            .Select(_continentMapper.CreateContinent)
            .ToList();

        return continents;
    }

    public Continent Get(long id)
    {
        var modelContinent = _httpContinentFetcher.GetContinent(id);
        var continent = _continentMapper.CreateContinent(modelContinent);

            return continent;
        }
  }

UsersController:工作正常。

    public class UsersController : ApiController
    {
        private readonly ISession _session;
        private readonly IUserManager _userManager;
        private readonly IUserMapper _userMapper;
        private readonly IHttpUserFetcher _userFetcher;

        public UsersController(
            IUserManager userManager,
            IUserMapper userMapper,
            IHttpUserFetcher userFetcher,
            ISession session)
        {
            _userManager = userManager;
            _userMapper = userMapper;
            _userFetcher = userFetcher;
            _session = session;
        }

        [Queryable]
        public IQueryable<Data.Model.User> Get()
        {
            return _session.Query<Data.Model.User>();
        }

        [LoggingNHibernateSession]
        public User Get(Guid id)
        {
            var user = _userFetcher.GetUser(id);
            return _userMapper.CreateUser(user);
        }
    }

我正在使用 NinjectWebCommon.cs在其中，我有这个和其他一些默认方法。:

        private static void RegisterServices(IKernel kernel)
        {
            var containerConfigurator = new NinjectConfigurator();
            containerConfigurator.Configure(kernel);

            GlobalConfiguration.Configuration.MessageHandlers.Add(kernel.Get<BasicAuthenticationMessageHandler>());
        }

然后我有NinjectConfigurator.cs :

public class NinjectConfigurator
{
    ......
    private void AddBindings(IKernel container)
        {
            .....
            container.Bind<IDateTime>().To<DateTimeAdapter>();
            container.Bind<IDatabaseValueParser>().To<DatabaseValueParser>();

            //HttpFetchers
            container.Bind<IHttpUserFetcher>().To<HttpUserFetcher>();
            container.Bind<IHttpContinentFetcher>().To<HttpContinentFetcher>();                                

            //TypeMappers
            container.Bind<IUserManager>().To<UserManager>();
            container.Bind<IMembershipInfoProvider>().To<MembershipAdapter>();
            container.Bind<IUserMapper>().To<UserMapper>();
            container.Bind<IContinentMapper>().To<ContinentMapper>();    
            .........
        }
     .......
}

两者都是 NinjectWebCommon.cs和 NinjectConfigurator.cs位于 App_Start文件夹。

container.Bind<ISession>().ToMethod(CreateSession);是NHibernate .在NinjectConfigurator.cs内里面private void ConfigureNHibernate(IKernel container) { ... }

Answer 1

您需要告诉 Ninject 如何正确解析 Web API 依赖项。

您可以使用 Felipe Oriani 的答案，但如果您愿意，可以使用名为 WebApiContrib.IoC.Ninject 的 NuGet 包来为您完成此操作。

1. 在 Visual Studio 中转到:工具 > NuGet 包管理器 > 管理解决方案的 NuGet 包

2. 安装WebApiContrib.IoC.Ninject包

3. 编辑:NinjectWebCommon.cs 并更新 CreateKernel() 方法以包括:GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);

   private static IKernel CreateKernel()
   {
       var kernel = new StandardKernel();
   
       try
       {
           kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
           kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
   
           RegisterServices(kernel);
   
           //Note: Add the line below:
           GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);
   
           return kernel;
       }
       catch
       {
           kernel.Dispose();
           throw;
       }
   }