EF6: How can I get navigation properties automatically updated?

Question

I've defined the following entities:
public abstract class EntityBase
public int Id { get; set; }
public string Name { get; set; }
public class Person : EntityBase
public virtual HashSet<Message> Messages { get; set; }
public int CountryId { get; set; }
public virtual Country Country { get; set; }
public class Message : EntityBase
public string Text { get; set; }
public int PersonId { get; set; }
public Person Person { get; set; }
public class Country : EntityBase
internal class TestContext : DbContext
public DbSet<Person> Persons { get; set; }
public DbSet<Country> Countries { get; set; }
Here's my problem: While the Messages.Person navigation property gets automatically updated according to the Messages.PersonId
foreign key property value when my changes get saved to the database, the Person.Country
navigation property remains null although the Person.CountryId
foreign key property is != 0.
Why is this happening? Why does the Messages.Person navigation property get aligned with the Messages.PersonId
foreign key property automatically while the Person.Country navigation property does not get aligned with the Person.CountryId
foreign key property?
These are the entity values before SaveChanges() is called:
person.CountryId = 1
person.Country = null
message.PersonId = 1
message.Person = null
And these are the entity values after SaveChanges() is called:
person.CountryId = 1
person.Country = null
message.PersonId = 1
message.Person = { Id = 1, Name = "Test" }
Your help is appreciated.
Still people out there alive using the keyboard?
Working with SQL Server/Office/Windows and their poor keyboard support they seem extinct...

Answer 1

Thank you for replying, Fred.
Here's the unit test code I'm using (it calls into a repository which more or less simply calls DbSet<Entity>::Add()
and SaveChanges();.
[TestMethod]
public void MessageDbTest()
using (Repository<Person> rp = new Repository<Person>(true))
Person p;
Message m;
BusinessLayer.TestContext.CreateNewDB();
rp.AddOrUpdate(p = new Person("Hello", 1));
Assert.AreEqual<int>(1, p.Id);
Assert.AreEqual<string>("Hello", p.Name);
m = new Message("Hello, too", p.Id, "This is a long test message.");
p.Messages.Add(m);
rp.AddOrUpdate(p);
Assert.AreSame(m, p.Messages.Single());
Assert.IsNotNull(m.Person);
Assert.AreEqual<int>(1, m.Id);
Assert.AreEqual<string>("Hello, too", m.Name);
Assert.AreEqual<string>("This is a long test message.", m.Text);
p = rp.GetItem(1);
p.Messages.Single().Name = "This works, too";
rp.AddOrUpdate(p);
[TestMethod]
public void CountryDbTest()
using (Repository<Person> rp = new Repository<Person>(true))
Person p;
Message m;
BusinessLayer.TestContext.CreateNewDB();
rp.AddOrUpdate(p = new Person("Hello", 1));
Assert.AreEqual<int>(1, p.Id);
Assert.AreEqual<string>("Hello", p.Name);
Assert.AreEqual<int>(1, p.CountryId);
Assert.IsNotNull(p.Country); // ** fails ! ***
Following is a number of screenshots, depicting the entities' properties.
Please notice the highlighted navigation property values in the Watch window on the right.
You will notice that while the Messages.Person navigation property gets aligned with the Messages.PersonId
foreign key property, the Person.Country navigation property does not get aligned with the Person.CountryId
foreign key property when TestContext::SaveChanges() is called:
Still people out there alive using the keyboard?
Working with SQL Server/Office/Windows and their poor keyboard support they seem extinct...