MVC5和Ninject依赖注入失败 [英] Dependency Injection fails with MVC5 and Ninject
问题描述
我试图在控制器中注入几个类,但是失败了.
I'm trying to inject a couple of classes in a controller, but I'm failing.
这就是我所做的:
- 添加了
Ninject.Web.WebApi.WebHost
和WebActivatorEx
NuGet软件包 - 在
App_Start
下创建了以下类:
- Added
Ninject.Web.WebApi.WebHost
andWebActivatorEx
NuGet packages - Created the following class under
App_Start
:
NinjectWebCommon.cs
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();
}
}
}
- 创建了我的课程:
MyContext.cs:
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
}
}
-
创建一个控制器
Created a Controller
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());
}
}
}
但是当我运行应用程序时,我仍然收到关于缺少无参数构造函数的声名狼藉的错误.这对我说DI无效.
But when I run the application I still get the infamous error about the missing of parameterless constructor. This says to me that DI is not working.
推荐答案
我相信您在RegisterServices
中的注册调用是错误的-无法绑定接口.ToSelf()
-您需要将接口绑定到混凝土类来实现它-像这样:
I believe your registration calls in RegisterServices
are wrong - you cannot bind an interface .ToSelf()
- you need to bind the interface to the concrete class that implements it - something like this:
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<IMyContext>().To<MyContext>().InRequestScope();
kernel.Bind<IErp>().To<Erp>().InRequestScope();
}
有了这个,您告诉DI容器在代码中每当需要IMyContext
依赖项时就实例化MyContext
类
With this, you tell the DI container to instantiate an MyContext
class whenever in your code you're expecting an IMyContext
dependency
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