EF 5.0 not removing optional one to one navigation property - entity-framework

Question

Setting an optional one to one navigation property to null in Entity Framework 5 does not seem to make it to the database. Is this expected behavior?
In the example below, Person is a proxy object. I would expect setting the address to null will cause the address to be removed from the database.
The code below works if I lazy load the address before setting it null. But loading the address before
Any help will be greatly appreciated.
namespace ConsoleApplication2
{
using System;
using System.Data.Entity;
internal class Program
{
private static void Main(string[] args)
{
using (PersonContext context = new PersonContext())
{
// Make sure person with Id = 1 exists with an address.
Person person = context.People.Find(1) ?? context.People.Add(new Person { Id = 1 });
if (person.Address == null)
{
person.Address = new Address
{
Street = "123 Main Street",
City = "SomeCity",
State = new State
{
Code = "NY",
Name = "New York"
},
Zip = "11771"
};
}
context.SaveChanges();
}
// Setting address to null should remove relationship
using (PersonContext context = new PersonContext())
{
Person person = context.People.Find(1);
Console.WriteLine("Person is a " + person.GetType());
person.Address = null;
context.SaveChanges();
if (person.Address == null)
{
Console.WriteLine("Success: Person.Address is null.");
}
else
{
Console.WriteLine("Failure: Person.Address is not null.");
}
}
}
}
public class Person
{
public int Id { get; set; }
public virtual Address Address { get; set; }
}
public class Address
{
public int Person_Id { get; set; }
public string Street { get; set; }
public string City { get; set; }
public int StateId { get; set; }
public State State { get; set; }
public string Zip { get; set; }
}
public class State
{
public int Id { get; set; }
public string Code { get; set; }
public string Name { get; set; }
}
public class PersonContext : DbContext
{
public DbSet<Person> People { get; set; }
public DbSet<State> States { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Address>()
.HasKey(x => x.Person_Id);
modelBuilder.Entity<Person>()
.HasOptional<Address>(x => x.Address)
.WithRequired()
.WillCascadeOnDelete();
}
}
}

Answer 1

Where you are not using lazy loading, the related properties such as Address will not be loaded and so will already be null.
To ensure it is always loaded use eager loading :
Person person = context.People.Include(x => x.Address).Single(x => x.Id == 1);