获取“MissingMethodException：无法创建接口的实例”当使用Ninject将通用接口绑定到存储库时 [英] Getting "MissingMethodException: Cannot create an instance of an interface" when binding generic interface to repository with Ninject

问题描述

按照指南这里 ，而不是StructureMap试图使用Ninject。

Following the guide here, but instead of StructureMap attempting to use Ninject.

它会抛出MissingMethodException：无法创建接口的实例错误，无论何时我尝试注入 IRepository< SomeEntityType> 添加到动作方法中的参数中。

It throws up the "MissingMethodException: Cannot create an instance of an interface" error any time I attempt to inject an IRepository<SomeEntityType> into a parameter in an action method.

更新：同样给出bootstrapper.cs， MVC3 Ninject Nuget包。

Update: Also giving bootstrapper.cs not found, I used the MVC3 Ninject Nuget package.

 public ActionResult Index(IRepository<SomeEntityType> repo)
        {


            return View();
        }

NinjectWebCommon.cs

NinjectWebCommon.cs

        private static void RegisterServices(IKernel kernel)
    {
        string Cname = "VeraDB";
        IDbContext context = new VeraContext("VeraDB");
        kernel.Bind<IDbContext>().To<VeraContext>().InRequestScope().WithConstructorArgument("ConnectionStringName", Cname);
        kernel.Bind(typeof(IRepository<>)).To(typeof(EFRepository<>)).WithConstructorArgument("context",context);

    }      

IRepository

IRepository

    public interface IRepository<T> where T : class
{
    void DeleteOnSubmit(T entity);
    IQueryable<T> GetAll();
    T GetById(object id);
    void SaveOrUpdate(T entity);
}

EFRepository

EFRepository

    public class EFRepository<T> : IRepository<T> where T : class, IEntity
{
    protected readonly IDbContext context;
    protected readonly IDbSet<T> entities;

    public EFRepository(IDbContext context)
    {
        this.context = context;
        entities = context.Set<T>();
    }

    public virtual T GetById(object id)
    {
        return entities.Find(id);
    }

    public virtual IQueryable<T> GetAll()
    {
        return entities;
    }

    public virtual void SaveOrUpdate(T entity)
    {
        if (entities.Find(entity.Id) == null)
        {
            entities.Add(entity);
        }

        context.SaveChanges();
    }

    public virtual void DeleteOnSubmit(T entity)
    {
        entities.Remove(entity);

        context.SaveChanges();
    }
}

IEntity只是作为一个泛型约束。

IEntity just acts as a generic constraint.

   public interface IEntity
{
    Guid Id { get; set; }
}

推荐答案

错误。 Ninject将参数注入到您的构造函数中，但是您向索引控制器操作添加了参数。

I made the same simple mistake. Ninject injects parameters into your constructor, but you added parameters to the Index Controller action.

它应该看起来像这样：

public class HomeController : Controller
{
    private IRepository<SomeEntityType> _repo;

    public HomeController(IRepository<SomeEntityType> repo)
    {
        _repo= repo;
    }

    public ActionResult Index()
    {
        ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application. " +
                          _repo.HelloWorld();

        return View();
    }
}

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