using Microsoft.EntityFrameworkCore;
using System.Collections.Generic;
using System.Linq;

namespace EFCoreTest
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            using (var db = new MyDbContext())
            {
                var set = db.Set<User>();
                if (db.Database.EnsureCreated())
                {
                    set.Add(new User
                    {
                        UserName = "test",
                        UserRoles = new List<UserRole>
                        {
                            new UserRole
                            {
                                Role=new Role{
                                    Name="admin"
                                }
                            }
                        }
                    });
                    db.SaveChanges();
                }
                //foreach (var item in set.ToList())
                //{
                //    set.Remove(item);
                //    db.SaveChanges();
                //}
                var user = set.Include(o => o.UserRoles).ThenInclude(o => o.Role).FirstOrDefault();
                user.UserRoles.FirstOrDefault().Role.Name = "test";
                db.SaveChanges();
            }
        }
    }
}