using System;

using System.Collections.Generic;

​

using Microsoft.Data.Sqlite;

using Microsoft.EntityFrameworkCore;

​

public class Program

{

    public static void Main()

    {

        using (var connection = new SqliteConnection("DataSource=:memory:"))

        {

            connection.Open();

            var options = new DbContextOptionsBuilder<TestDatabaseContext>()

                //.UseInMemoryDatabase(databaseName: "Test")

                .UseSqlite(connection)

                .Options;

            using (var db = new TestDatabaseContext(options))

            {

                db.Database.EnsureCreated();

            }

​

            using (var db = new TestDatabaseContext(options))

            {

                db.Devices.Add(new Device { Id = 1, OperatingSystem = "Android" });

                db.Devices.Add(new Device { Id = 2, OperatingSystem = "iOS" });

                db.Devices.Add(new Device { Id = 3, OperatingSystem = "Windows10"});

                db.Devices.Add(new Device { Id = 4, OperatingSystem = "Windows11"});

                db.SaveChanges();

            }

​

​

            using (var db = new TestDatabaseContext(options))

            {

                foreach (Device device in db.Devices)

                {

                    Console.WriteLine("Device Id: " + device.Id + ", name: '" + device.OperatingSystem + "'.");

                }

            }

​

​

            using (var db = new TestDatabaseContext(options))

            {

                var user1 = new User() { Name = "TestUser1" };

                var device1 = db.Devices.FirstOrDefaultAsync(d => d.Id == 1).Result;

                user1.Devices.Add(device1);

​

                db.Users.Add(user1);

                db.SaveChanges();

​

                var user2 = new User() { Name = "TestUser2" };

                user2.Devices.Add(db.Devices.FirstOrDefaultAsync(d => d.Id == 1).Result);

                user2.Devices.Add(db.Devices.FirstOrDefaultAsync(d => d.Id == 3).Result);

​

                db.Users.Add(user2);

                db.SaveChanges();   

            }

​

​

            using (var db = new TestDatabaseContext(options))

            {

                foreach (User user in db.Users.Include(d => d.Devices))

                {

​

​

                    foreach (Device device in user.Devices)

                    {

                        Console.WriteLine("User Id: " + user.Id + ", username: '" + user.Name + "', Device Id: " + device.Id + ", name: '" + device.OperatingSystem + "'.");

                    }

                }

            }

        }

    }

    internal class TestDatabaseContext : DbContext

    {

        public DbSet<User> Users

        {

            get;

            set;

        }

        public DbSet<Device> Devices

        {

            get;

            set;

        }

        public TestDatabaseContext()

        {

        }

        public TestDatabaseContext(DbContextOptions<TestDatabaseContext> options) : base(options)

        {

        }

    }

    internal class User

    {

        public int Id

        {

            get;

            set;

        }

        public string Name

        {

            get;

            set;

        }

        public List<Device> Devices

        {

            get;

            set;

        } = new();

    }

    internal class Device

    {

        public int Id

        {

            get;

            set;

        }

        public string OperatingSystem

        {

            get;

            set;

        }

        public List<User> Users

        {

            get;

            set;

        } = new();

    }

}