c# - 在将 OnModelCreating 与 ApplicationDbContext 一起使用时解决 'No key Defined' 错误？

Question

我一直在尝试为我的集合类型创建导航属性，我发现了 this example一个人如何使用 OnModelCreating 完成它。我在我的 MVC 5 应用程序中试了一下，在尝试更新我的数据库时收到此错误:

One or more validation errors were detected during model generation:

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

如何解决这些“未定义 key ”错误？

我做了一些搜索，找到了 this solution对于一个用户问题，但他的需求与我的不同。这些解决方案对于我正在尝试做的事情来说似乎相当复杂。

这是导致问题的代码:

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        public ApplicationDbContext()
            : base("DefaultConnection", throwIfV1Schema: false)
        {

        }
        //public DbSet<Image> Images { get; set; }

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

        public DbSet<Post> Posts { get; set; }
        public DbSet<Image> Images { get; set; }
        public DbSet<Album> Albums { get; set; }
        public DbSet<Tag> Tags { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            modelBuilder.Entity<Post>().
                 HasOptional(e => e.Tags).
                 WithMany().
                 HasForeignKey(m => m.Tags_Id);

            modelBuilder.Entity<Tag>().
                 HasOptional(e => e.Posts).
                 WithMany().
                 HasForeignKey(m => m.Posts_Id);
        }

    }

这是我的多对多关系模型:

Post.cs model on Gist

Tag.cs model on Gist

---

更新以显示 IdentityUser:

public class ApplicationUser : IdentityUser
    {
        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;
        }
    }

Answer 1

您可能需要向 OnModelCreating 添加如下内容

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 });

另请参阅:

• Map tables using fluent api in asp.net MVC5 EF6?
• User in Entity type MVC5 EF6