EF Core - Added element of relation isnt being saved by EF

Question

I have problem with adding new object's to collection inside user class (relation) one-to-many, one user can have many items

But for some reason context is not saving it properly inside User.

Result of this code:

• User is added to the _context.UsersTable and can be read from other controllers

• Item is added to the _context.ItemsTable (and can be read from other controllers), but there's no connection between User and Item.

• Items collection at user is always empty.

  public class User
  {
      [Key]
      public Guid Id { get;  set; }
      public virtual ICollection<Item> Items { get; set; } = new HashSet<Items>();
      protected User()
      {
  
      }
      public User(string login, string password)
      {
          (...)
      }
  }
  
  public class Item
  {
      [Key]
      public virtual User User { get; set; }
      public string ItemName { get; set; }
  
      protected Item()
      {
  
      }
  
      public Item(string name, User user)
      {
          Id = new Guid();
          this.User = user;
          ItemName = name;
      }
  }
  
  public class AppContext : DbContext
  {
      public AppContext(DbContextOptions<AppContext> options) : base(options)
      {
          Database.SetCommandTimeout(35000);
      }
  
      public DbSet<User> UsersTable { get; set; }
      public DbSet<Items> ItemsTable { get; set; }
  }
  
  
  
  public IActionResult register([FromBody]Register command)
  {
      var newUser = new User(command.login, password);
      var newItem = new Item("TEST", newUser);
  
      _context.Entry(newUser).State = EntityState.Modified;
  
      newUser.Items.Add(newItem);
  
      _context.UsersTable.Add(newUser);
  
      _context.ItemsTable.Add(newItem);
  
      _context.SaveChanges();
  }
  

Answer 1

Your Item class is wrong, you need this :

public class Item
{
    [Key]
    public Guid Id { get; set; }

    public string ItemName { get; set; }

    // Relation to User
    public Guid UserId { get; set; }
    public virtual User User { get; set; }

    protected Item()
    {    }

    public Item(string name, User user)
    {
        Id = Guid.NewGuid();
        UserId = user.Id;
        ItemName = name;
    }
}

And the register method :

public IActionResult register([FromBody]Register command)
{
    var newUser = new User(command.login, password);
    var newItem = new Item("TEST", newUser);

    newUser.Items.Add(newItem);
    _context.UsersTable.Add(newUser);
    _context.ItemsTable.Add(newItem); // Edit : I'm not sure, but try it without this line, it should work
    _context.SaveChanges();
}