Create Standalone Entity-Framework Model-Test

Demo-Entity-Framework.cs

class Program
{
    static void Main(string[] args)
    {
        Database.SetInitializer(new DropCreateDatabaseAlways<PeopleContext>());
        
        var context = new PeopleContext();
        context.Database.Log = Console.WriteLine; // so we can inspect SQL statements

        AddOnePerson(context);

        var people = context.Persons.Include(x => x.Address).ToList();
        Console.WriteLine("We have " + people.Count + " people in db.");

        Console.WriteLine("done.");
        Console.ReadKey();
    }

    private static void AddOnePerson(PeopleContext context)
    {
        // We need to create new Person without AddressId, save that to db to get its Id
        // and then create Address and fill both ends of relationship (PersonId and AddressId)
        // That's why Person.AddressId is nullable.

        var john = new Person {Name = "john"};
        context.Persons.Add(john);
        context.SaveChanges();

        var address = new Address() {StreetName = "street", PersonId = john.Id};
        john.Address = address;
        context.Addresses.Add(address);
        context.SaveChanges();
    }
}

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int? AddressId { get; set; } // notice nullabe foreign key!
    public virtual Address Address { get; set; }
}

public class Address
{
    public int Id { get; set; }
    public string StreetName { get; set; }
    public int PersonId { get; set; }
    public virtual Person Person { get; set; }
}

public class PeopleContext : DbContext
{
    public IDbSet<Person> Persons { get; set; }
    public IDbSet<Address> Addresses { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // one to many Person - Address
        modelBuilder.Entity<Person>()
            .HasOptional(x => x.Address).WithMany()
            .HasForeignKey(x => x.AddressId);

        // one to many Address - Person
        modelBuilder.Entity<Address>()
            .HasRequired(x => x.Person).WithMany()
            .HasForeignKey(x => x.PersonId);
    }
}