存储库不能用作方法的通用类型中的类型参数

Question

I recently came across a problem which I haven't met before about dependencies and looked it up and found Ninject. I have followed a guide on how to use it and have reached a point where I receive and error which I do not understand. I very generally wrote down the error in the title but the full error is as follows:

'Error 1 The type 'MyDBFirstAP.Repository.SQLAPRepository' cannot be used as type parameter 'TImplementation' in the generic type or method 'Ninject.Syntax.IBindingToSyntax.To()'. There is no implicit reference conversion from 'MyDBFirstAP.Repository.SQLAPRepository' to 'MyDBFirstAP.Repository.IAPRepository'.'

It occurs here:

public class NinjectControllerFactory : DefaultControllerFactory{
    private IKernel ninjectKernel;

    public NinjectControllerFactory() {
        ninjectKernel = new StandardKernel();
        AddBindings();
    }
    protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType) {
        return controllerType == null
            ? null
            : (IController)ninjectKernel.Get(controllerType);
    }
    private void AddBindings()
    {
        ninjectKernel.Bind<IAPRepository>().To<SQLAPRepository>(); // On this line
    }
}

The beginning of my controller is as:

 public class ClientsController : Controller
    {
        IAPRepository repository;

        // GET: Clients
        public ClientsController(IAPRepository repository) {
            this.repository = repository;
        }

Here is the requested SQLRepository code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using MyDBFirstAP.Models;
using MyDBFirstAP.DI;

namespace MyDBFirstAP.Repository {
    public class SQLAPRepository {
        ApplicationDbContext Database = new ApplicationDbContext();

        #region Client
        public IQueryable<Client> GetAllClients() {
            return Database.Clients;
        }    

        public Client GetClientByID(int id) {
            return Database.Clients.FirstOrDefault(c => c.ClientID == id);
        }

        public IQueryable<Client> GetClientByName(string ClientName) {

            return (from clients in Database.Clients
                    where clients.ClientName.Contains(ClientName)
                    select clients);

        }

        public void AddClient(Client client) {
            Database.Clients.Add(client);
            Database.SaveChanges();
        }

        public void UpdateClient(Client client) {
            var tmpClient = Database.Clients.FirstOrDefault(c => c.ClientID == client.ClientID);
            tmpClient.ClientName = client.ClientName;
            tmpClient.ClientAddress = client.ClientAddress;
            Database.SaveChanges();
        }
        public void DeleteClient(Client client) {
            Database.Clients.Remove(client);
            Database.SaveChanges();
        }
#endregion

        #region Supplier
        public IQueryable<Supplier> GetAllSuppliers() {
            return Database.Suppliers;
        }

        public Supplier GetSupplierByID(int id) {
            return Database.Suppliers.FirstOrDefault(s => s.SupplierID == id);
        }

        public IQueryable<Supplier> GetSupplierByName(string SupplierName) {
            return(from suppliers in Database.Suppliers
                       where suppliers.SupplierName.Contains(SupplierName)
                       select suppliers);
        }

        public void AddSupplier(Supplier supplier) {
            Database.Suppliers.Add(supplier);
            Database.SaveChanges();
        }

        public void UpdateSupplier(Supplier supplier) {
            var tmpSupplier = Database.Suppliers.FirstOrDefault(s => s.SupplierID == supplier.SupplierID);
            tmpSupplier.SupplierName = supplier.SupplierName;
            tmpSupplier.SupplierAddress = supplier.SupplierAddress;
            Database.SaveChanges();
        }

        public void DelteSupplier(Supplier supplier) {
            Database.Suppliers.Remove(supplier);
            Database.SaveChanges();
        }
        #endregion

        #region Claim
        public IQueryable<Claim> GetAllClaims() {
            return Database.Claims;
        }

        public Claim GetClaimByID (int id) {
            return Database.Claims.FirstOrDefault(c => c.ClaimID == id);
        }

        public void AddClaim(Claim claim) {
            Database.Claims.Add(claim);
            Database.SaveChanges();
        }
        public void UpdateClaim(Claim claim) {
            var tmpClaim = Database.Claims.FirstOrDefault(c => c.ClaimID == claim.ClaimID);
            tmpClaim.ClaimTotal = claim.ClaimTotal;
            tmpClaim.ClaimWIP = claim.ClaimWIP;
            tmpClaim.FK_ClientID = claim.FK_ClientID;
            tmpClaim.FK_SupplierID = claim.FK_SupplierID;
            Database.SaveChanges();
        }
        public void DeleteClaim(Claim claim) {
            Database.Claims.Remove(claim);
            Database.SaveChanges();
        }
        #endregion
    }
}

Can someone please help me understand this error and also help my fix it please. Thank you.

Answer 1

SQLAPRepository must implement IAPRepository.

public class SQLAPRepository : IAPRepository
{
     ....
}

Answer 2

as Radin said it must implement the IAPRepository interface. When you do dependency injection you're allowing any implementation of an interface to be used at runtime. For production code there is either an explicit configuration mapping or some kind of interrogation of available implementations at runtime.

In NancyFX TinyIoC is used, and it does not require explicit type mapping. For other solutions like Unity there is an explicit type mapping done for many implementations container.RegisterType<IMyInterface,MyImplementation>();