没有为此对象定义无参数构造函数-MVC项目

Question

I am trying to create a MVC project without Entity framework and I get this error. No parameterless constructor defined for this object. I am pretty new in C# and I would like some help. Here is my code: First the model Movies.cs

    using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Web;

namespace MyMovies.Models
{
    public class Movie
    {
        public int ID { get; set; }
        public string Title { get; set; }
        public DateTime ReleaseDate { get; set; }
        public string Genre { get; set; }
        public decimal Price { get; set; }
        public string Rating { get; set; }
    }

    public interface IMovieRepository
    {
        IEnumerable<Movie> Get();

    }

    public class MovieDBRepository : IMovieRepository
    {
        public IEnumerable<Movie> Get()
        {
            string connectionString = "Connection";
            using (var conn = new SqlConnection(connectionString))
            using (var cmd = conn.CreateCommand())
            {
                conn.Open();
                cmd.CommandText = "SELECT ID, Title, Date, Genre, Rating";
                using (var reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        yield return new Movie
                        {
                            ID = reader.GetInt32(reader.GetOrdinal("ID")),
                            Title = reader.GetString(reader.GetOrdinal("name")),
                            ReleaseDate = reader.GetDateTime(reader.GetOrdinal("ReleaseDate")),
                            Genre = reader.GetString(reader.GetOrdinal("Genre")),
                            //Price = reader.GetFloat(reader.GetOrdinal.("Price")),
                            Rating = reader.GetString(reader.GetOrdinal("Rating"))
                        };
                    }
                }
            }
        }
    }
}

and this is the controller

using MyMovies.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace MyMovies.Controllers
{
    public class MovieController : Controller
    {



        private readonly IMovieRepository repository;
            public MovieController(IMovieRepository repository)
            {
                this.repository = repository;
            }
            // GET: Movie
            public ActionResult Index()
            {
                var movie = this.repository.Get();
                return View(movie);
            }


            }
    }

Answer 1

You cannot specify a parameter in the constructor for a controller if you do not have a dependency injection framework registered.

Either change this:

        public MovieController(IMovieRepository repository)
        {
            this.repository = repository;
        }

to

        public MovieController()
        {
            this.repository = new MovieDBRepository();
        }

or set up a dependency injection engine such as Unity, Ninject, or fFastInjector.