Resolving 'No key Defined' errors while using OnModelCreating with ApplicationDbContext?

问题

I've been trying to create navigation properties for my collection types and I found this example of how one person accomplished it using OnModelCreating. I gave it a try in my MVC 5 application and I recieved this error when trying to update my database:

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.

How do I resolve these 'No key Defined' errors?

I did some searching and I found this solution for one users problem, but his needs were different than mine. The solutions seemed pretty convoluted for what I am trying to do.

This is the code that causes the issue:

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);
        }

    }

Here are my to models with the many to many relationship:

Post.cs model on Gist

Tag.cs model on Gist

---

Update to show 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;
        }
    }

回答1:

You might have to add something like the following to OnModelCreating

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 });

See also:

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

回答2:

I think the issue is that you have removed the calling of base class from OnModelCreating. Try adding that also as shown below

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

        //Your configuration goes here
    }

回答3:

I know this is a late response, and this may only work for people working off tutorials or school projects!

For me, just deleting the database, .mdf, and migrations folder fixed it. Now, I don't know if you are using migrations, but this worked for me.

I'm a novice, but what I've noticed is that Identity is very finicky with keys. Deleting the migration has helped with every (godforsaken) migration problem I've hit with my project.

来源：https://stackoverflow.com/questions/30315968/resolving-no-key-defined-errors-while-using-onmodelcreating-with-applicationdb