c# - EntityType 未定义键

Question

我正在创建一个应用程序，用户可以在其中通过 Facebook oAuth 登录，然后设置歌曲列表。我收到以下错误消息:

BandFinderCsharp.Models.IdentityUserLogin: : EntityType 'IdentityUserLogin' has no key defined. Define the key for this EntityType.

BandFinderCsharp.Models.IdentityUserRole: : EntityType 'IdentityUserRole' has no key defined. Define the key for this EntityType.

IdentityUserLogins: EntityType: EntitySet 'IdentityUserLogins' is based on type 'IdentityUserLogin' that has no keys defined.

IdentityUserRoles: EntityType: EntitySet 'IdentityUserRoles' is based on type 'IdentityUserRole' that has no keys defined.

---

错误消息出现在我的 SongsController 中:

`namespace BandFinder.Controllers.Bread
{
    public class SongsController : Controller
    {
        private SongDBContext db = new SongDBContext();

        // GET: Songs
        public ActionResult Index()
        {
            return View(db.Songs.ToList()); <--- This is where the error occurs
        }

        // GET: Songs/Details/5
        public ActionResult Details(long? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Song song = db.Songs.Find(id);
            if (song == null)
            {
                return HttpNotFound();
            }
            return View(song);
        }

        // GET: Songs/Create
        public ActionResult Create()
        {
            return View();
        }

        // POST: Songs/Create
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create([Bind(Include = "Id,UserId,BandId,Title,Artist,Genre,ListId,CreatedOn")] Song song)
        {
            if (ModelState.IsValid)
            {
                song.CreatedOn = DateTime.Now;
                db.Songs.Add(song);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            return View(song);
        }

        // GET: Songs/Edit/5
        public ActionResult Edit(long? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Song song = db.Songs.Find(id);
            if (song == null)
            {
                return HttpNotFound();
            }
            return View(song);
        }

        // POST: Songs/Edit/5
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
        // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Edit([Bind(Include = "Id,UserId,BandId,Title,Artist,Genre,ListId,CreatedOn")] Song song)
        {
            if (ModelState.IsValid)
            {
                db.Entry(song).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            return View(song);
        }

        // GET: Songs/Delete/5
        public ActionResult Delete(long? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Song song = db.Songs.Find(id);
            if (song == null)
            {
                return HttpNotFound();
            }
            return View(song);
        }

        // POST: Songs/Delete/5
        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public ActionResult DeleteConfirmed(long id)
        {
            Song song = db.Songs.Find(id);
            db.Songs.Remove(song);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                db.Dispose();
            }
            base.Dispose(disposing);
        }
    }
}`

我不明白的是，这个 Controller 与 IdentityUser 代码无关..

这是我的 ApplicationUser 模型:

namespace BandFinderCsharp.Models
{
    public class ApplicationUser : IdentityUser
    {
        public ApplicationUser()
        {
            CreatedOn = DateTime.Now;
            this.ProfileImage  = new byte[0];
            this.facebookImage = new byte[0];
        }

        public byte[] facebookImage { get; set; }

        [MaxLength(32)]
        public string FirstName { get; set; }

        [MaxLength(32)]
        public string LastName { get; set; }

        public byte[] ProfileImage { get; set; }

        //public virtual ICollection<Instrument> Instruments { get; set; }
        //public virtual ICollection<Song> Songs { get; set; }
        //public virtual ICollection<Band> Bands { get; set; }

        public string Zipcode { get; set; }

        [Index]
        public float Longitude { get; set; }

        [Index]
        public float Latitude { get; set; }

        [Required]
        [DatabaseGenerated(DatabaseGeneratedOption.None)]
        public DateTime CreatedOn { get; set; }
        //////////////

        public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager)
        {
            // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType
            var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);
            // Add custom user claims here
            return userIdentity;
        }
    }

    public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<IdentityUserLogin>().HasKey<string>(l => l.UserId);
            modelBuilder.Entity<IdentityRole>().HasKey<string>(r => r.Id);
            modelBuilder.Entity<IdentityUserRole>().HasKey(r => new { r.RoleId, r.UserId });
            base.OnModelCreating(modelBuilder);
        }

        public ApplicationDbContext()
            : base("DefaultConnection", throwIfV1Schema: false)
        {
        }

        public static ApplicationDbContext Create()
        {
            return new ApplicationDbContext();
        }
    }
}

---

为什么我在从歌曲 Controller 引用身份模型时收到错误消息？此时两者之间应该没有相关性。

IdentityUser 类是内置的 .NET 类，我认为我无法对其进行编辑:

namespace Microsoft.AspNet.Identity.EntityFramework
{
    //
    // Summary:
    //     Default EntityFramework IUser implementation
    public class IdentityUser : IdentityUser<string, IdentityUserLogin, IdentityUserRole, IdentityUserClaim>, IUser, IUser<string>
    {
        //
        // Summary:
        //     Constructor which creates a new Guid for the Id
        public IdentityUser();
        //
        // Summary:
        //     Constructor that takes a userName
        //
        // Parameters:
        //   userName:
        public IdentityUser(string userName);
    }
}

IdentityUserLogin

namespace Microsoft.AspNet.Identity.EntityFramework
{
    //
    // Summary:
    //     Entity type for a user's login (i.e. facebook, google)
    public class IdentityUserLogin : IdentityUserLogin<string>
    {
        public IdentityUserLogin();
    }
}

Answer 1

如果 ApplicationUser 类是您要保存在数据库中的对象，那么它必须包含一个名为 Id 的字段，默认情况下它是主键 Entity Framework 链接到的对象。

你的对象应该是这样的:

public class ApplicationUser
{
    public int Id { get; set; }
    public string Name { get; set; }
}

或者，如果您想将不同的属性设置为对象的主键，您应该在该字段上方添加 [Key] 属性 - 您还需要添加 System.ComponentModel.DataAnnotations 命名空间:

public class ApplicationUser
{
    public int Id { get; set; }
    [Key]
    public string Name { get; set; }
}