Custom IdentityRole<TKey, TUserRole> fails when hiding the Id property

Question

Question in relation to this, here...

UserManager.AddToRole not working - Foreign Key error

In my application I have a custom Role implementation

public class Role : IdentityRole<Guid, UserRole>
{
    public const string Admininstrator = "Administrator";

    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public new Guid Id { get; set; }
}

but when used causes this error

The INSERT statement conflicted with the FOREIGN KEY constraint "FK_dbo.AspNetUserRoles_dbo.AspNetRoles_RoleId". The conflict occurred in database "TestDatabase", table "dbo.AspNetRoles", column 'Id'.

The culprit is this...

[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public new Guid Id { get; set; }

removing this from the class and manually creating a unique ID works...

public Role()
{
    Id = Guid.NewGuid();
}

I would prefer the database did this for me - any ideas why this is failing?

Answer 1

Remove

[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public new Guid Id { get; set; }

just

   public class Role : IdentityRole<Guid, UserRole>{ }

and add DatabaseGeneratedOption.Identity with fluent api! In custom IdentityDbContext class add

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
     base.OnModelCreating(modelBuilder);
     // identity
     modelBuilder.Entity<Role>().Property(r => r.Id)
         .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
}

When you add-migration you will see (Id = c.Guid(nullable: false, identity: true))

CreateTable(
    "dbo.AspNetRoles",
     c => new
          {
                Id = c.Guid(nullable: false, identity: true),
                Name = c.String(nullable: false, maxLength: 256),
          })
    .PrimaryKey(t => t.Id)
    .Index(t => t.Name, unique: true, name: "RoleNameIndex");