MVC5 和 Ninject 的依赖注入失败

我试图在控制器中注入几个类，但失败了。

这就是我所做的：

1. Added Ninject.Web.WebApi.WebHost and WebActivatorExNuGet 包
2. 在下面创建了以下类App_Start:

NinjectWebCommon.cs

using Microsoft.Web.Infrastructure.DynamicModuleHelper;
using Ninject;
using Ninject.Web.Common;
using Ninject.Web.Common.WebHost;
using MyProject;
using MyProject.Models;
using MyProject.Classes;
using System;
using System.Web;

[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(NinjectWebCommon), "Start")]
[assembly: WebActivatorEx.ApplicationShutdownMethodAttribute(typeof(NinjectWebCommon), "Stop")]

namespace MyProject
{
    public static class NinjectWebCommon
    {
        private static readonly Bootstrapper bootstrapper = new Bootstrapper();

        public static void Start()
        {
            DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
            DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
            bootstrapper.Initialize(CreateKernel);
        }

        public static void Stop()
        {
            bootstrapper.ShutDown();
        }

        private static IKernel CreateKernel()
        {
            var kernel = new StandardKernel();
            kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
            kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

            RegisterServices(kernel);
            return kernel;
        }

        private static void RegisterServices(IKernel kernel)
        {
            kernel.Bind<IMyContext>().ToSelf().InRequestScope();
            kernel.Bind<IErp>().ToSelf().InRequestScope();
        }
    }
}

3. 创建了我的课程：

MyContext.cs：

using MyProject.Models;
using System;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;
using System.Threading.Tasks;

namespace MyProject.Models
{
    public interface IMyContext : IDisposable
    {
        DbSet<Operator> Operators { get; set; }
        Task<int> SaveChangesAsync();
    }

    public class MyContext : DbContext, IMyContext
    {
        public MyContext () : base("MyContext ") { }
        public DbSet<Operator> Operators { get; set; }
        public async override Task<int> SaveChangesAsync()
        {
            return await SaveChangesAsync(CancellationToken.None);
        }
    }
}

Erp.cs

public interface IErp
{
    Task ImportListAsync();
}

public class Erp : IErp
{
    private readonly IMyContext _context;
    public Erp(IMyContext context)
    {
        _context = context;
    }

    public async Task ImportListAsync()
    {
        // do something
    }
}

4. 创建了一个控制器

   using MyProject.Classes;
   using MyProject.Models;
   using System.Data.Entity;
   using System.Threading.Tasks;
   using System.Web.Mvc;
   
   namespace MyProject.Controllers
   {
       public class OperatorsController : Controller
       {
           private readonly IMyContext _context;
           private readonly IErp _erp;
   
           public OperatorsController(IMyContext context, Erp Ierp)
           {
               _context = context;
               _erp = erp;
           }
   
           // GET: Operators
           public async Task<ActionResult> Index()
           {
               return View(await _context.Operators.ToListAsync());
           }
   
           // GET: Operators/Import
           public async Task<ActionResult> Import()
           {
               await _erp.ImportListAsync();
               return View("Index", await _context.Operators.ToListAsync());
           }
       }
   }
   

但是当我运行该应用程序时，我仍然收到有关缺少无参数构造函数的臭名昭著的错误。这对我来说 DI 不起作用。

我相信您的注册电话RegisterServices是错误的 - 你不能绑定接口.ToSelf()- 您需要将接口绑定到具体类实现它 - 像这样：

private static void RegisterServices(IKernel kernel)
{
    kernel.Bind<IMyContext>().To<MyContext>().InRequestScope();
    kernel.Bind<IErp>().To<Erp>().InRequestScope();
}

这样，您就可以告诉 DI 容器实例化一个MyContext每当你的代码中你期望一个类IMyContext依赖性