Why does a Required IdentityUser property result in a nullable database field? - asp.net

Question

I want to require that all entities of a particular type have a corresponding user in my ASP.NET MVC app, and that this is enforced at the database level i.e. as a non-nullable field. However, when I set the Required attribute on the IdentityUser property in my model class, like so:
using Microsoft.AspNetCore.Identity;
using System.ComponentModel.DataAnnotations;
namespace Test.Models
{
public class Foo
{
public int Id { get; set; }
[Required]
public IdentityUser User { get; set; }
}
}
the corresponding migration that gets generated sets the UserId table field to nullable:
UserId = table.Column<string>(type: "TEXT", nullable: true)
I've read that Table Per Hierarchy can cause this, but I'm not using any kind of inheritance.
What am I missing? Is there a way to achieve what I want?

Answer 1

Try to fix your class
public class Foo
{
[Key]
public int Id { get; set; }
[Required]
public string UserId { get; set; }
[ForeignKey(nameof(UserId))]
public IdentityUser User { get; set; }
}
Net 5 automatically creates a shadow property UserId in order you could save your Foo class. Since you used [Required], EF automatically added that it is nullable. If this property was not able to be null (for example if it was int type ( not int? ! )) you would not need a [Required] attribute.

Answer 2

Also what you can do is to use Fluent API to configure your contraints.
public class Foo
{
public int Id { get; set; }
public string UserId { get; set; }
public IdentityUser User { get; set; }
}
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
public ApplicationDbContext()
: base("DefaultConnection", throwIfV1Schema: false)
{
}
public DbSet<Foo> Foos { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Foo>()
.HasRequired(c => c.User)
.WithMany(d => d.Foos)
.HasForeignKey(c => c.UserId);
}
}