Ninject：实体对象不能被IEntityChangeTracker的多个实例引用

我开始在我的MVC5代码优先应用程序中使用Ninject。 这是我的NinjectWebCommon.cs：

private static IKernel CreateKernel() { var kernel = new StandardKernel(); try { kernel.Bind<Func>().ToMethod(ctx => () => new Bootstrapper().Kernel); kernel.Bind().To(); kernel.Bind() .ToSelf() //.InSingletonScope(); .InRequestScope(); kernel.Bind() .To(); kernel.Bind() .To(); kernel.Bind() .To(); kernel.Bind() .To(); kernel.Bind() .To(); RegisterServices(kernel); return kernel; } catch { kernel.Dispose(); throw; } } 

我试过.InSingletonScope（）以及.InRequestScope（）但我仍然得到’ 实体对象不能被多个IEntityChangeTracker实例引用 ‘错误。 这是我的界面：

  public interface IExecutiveRepository : IDisposable { IEnumerable GetExecutives(); Executive GetExecutiveById(int executiveId); void InsertExecutive(Executive executive); void UpdateExecutive(Executive executive); void DeleteExecutive(int executiveId); void Save(); } 

这是我的具体内容：

  public class ExecutiveRepository : IExecutiveRepository, IDisposable { private CMSContext context; public ExecutiveRepository(CMSContext context) { this.context = context; } public IEnumerable GetExecutives() { return context.Executives.ToList(); } public Executive GetExecutiveById(int id) { return context.Executives.Find(id); } public void InsertExecutive(Executive executive) { context.Executives.Add(executive); } public void DeleteExecutive(int executiveId) { Executive executive = context.Executives.Find(executiveId); context.Executives.Remove(executive); } public void UpdateExecutive(Executive executive) { context.Entry(executive).State = EntityState.Modified; } public void Save() { context.SaveChanges(); } private bool disposed = false; protected virtual void Dispose(bool disposing) { if (!this.disposed) { if (disposing) { context.Dispose(); } } this.disposed = true; } public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } } 

这是控制器（顶部相关部分）：

  public class ExecutiveController : Controller { private IExecutiveRepository executiveRepository; private IUserRepository userRepository; private IExecutiveSectionRepository executiveSectionRepository; private IExecutiveSectionMappingRepository executiveSectionMappingRepository; private IContentRepository contentRepository; private Ninject.IKernel _kernel = new StandardKernel(); //[Inject] public ExecutiveController() { executiveRepository = _kernel.Get(); userRepository = _kernel.Get(); executiveSectionRepository = _kernel.Get(); executiveSectionMappingRepository = _kernel.Get(); contentRepository = _kernel.Get(); } ... 

不知道我做错了什么，但在添加一个新的’执行’它炸弹…我明白它试图使用单独的上下文，这是问题，但我只是不知道如何解决它。 显然，NinjectWebCommon.cs类中的行：

  kernel.Bind() .ToSelf() //.InSingletonScope(); .InRequestScope(); 

应该是修复，但它不是……任何想法/建议？

Answer 1

你应该使用NUGET包Ninject.Web.Mvc如果你还没有。 这会将您的应用程序配置为使用Ninject，而不是绑定。 看起来你已经熟悉了我在CreateKernel()方法中看到的东西的绑定方面。

绑定到位后，您不应该在控制器中创建内核，这是因为Ninject.Web.Mvc库配置Ninject为您创建控制器。 因此，应自动解决您添加到它们的任何依赖项。

因此，您可以使用构造函数注入来解决依赖关系：

 public class ExecutiveController : Controller { private IExecutiveRepository ExecutiveRepository; private IUserRepository UserRepository; private IExecutiveSectionRepository ExecutiveSectionRepository; private IExecutiveSectionMappingRepository ExecutiveSectionMappingRepository; private IContentRepository ContentRepository; public ExecutiveController( IExecutiveRepository executiveRepository, IUserRepository userRepository, IExecutiveSectionRepository executiveSectionRepository, IExecutiveSectionMappingRepository executiveSectionMappingRepository, IContentRepository contentRepository) { // Set the field values this.ExecutiveRepository = executiveRepository, this.UserRepository = userRepository, this.ExecutiveSectionRepository = executiveSectionRepository, this.ExecutiveSectionMappingRepository = executiveSectionMappingRepository, this.ContentRepository = contentRepository; } public ActionResult Index(int id) { // Use one of your dependencies... var executive = this.executiveRepository.GetExecutiveById(id); } } 

或者您可以使用具有相同效果的[Inject]属性：

 public class ExecutiveController : Controller { [Inject] public IExecutiveRepository executiveRepository { get; set; } [Inject] public IUserRepository userRepository { get; set; } [Inject] public IExecutiveSectionRepository executiveSectionRepository { get; set; } [Inject] public IExecutiveSectionMappingRepository executiveSectionMappingRepository { get; set; } [Inject] public IContentRepository contentRepository { get; set; } public ExecutiveController() { } public ActionResult Index(int id) { // Use one of your dependencies... var executive = this.executiveRepository.GetExecutiveById(id); } } 

Answer 2

您正在为每个控制器创建一个内核。

InRequestScope仅确保每个内核的每个请求一个实例。

所以你需要调整你的内核设置，这样每个web应用程序只有一个内核。 看到：

• Ninject.Web.Mvc
• 教程
• 的Youtube

Answer 3

这可能无法回答这个问题。 但我倾向于使用EF为您提供的IDbContextFactory并执行以下操作：

 public interface IDefaultContextFactory : IDbContextFactory {} public class DefaultContextFactory : IDefaultContextFactory { private readonly Lazy lazyContext = new Lazy(() => new CMSContext()); public CMSContext Create() { return lazyContext.Value; } } 

然后你只需绑定它，当你需要上下文时，你可以做这样的事情：

 public class ExecutiveRepository : IExecutiveRepository, IDisposable { private readonly CMSContext context; public ExecutiveRepository(IDefaultContextFactory contextFactory) { this.context = contextFactory.Create(); } } 

我相信@BatteryBackupUnit是正确的，我也会考虑将上述模式用于上下文。