Entity Framework won't detect changes of navigation properties

Question

I\'m having trouble with detecting changes of a navigation property:

My testing model looks like this:

public class Person
{
    public int Id { get;         


        

Answer 1

You need to include the Address nav. prop. in your query, otherwise EF won't consider changes to it when you save :

using (var ctx = new EFContext())
{
    Person p = ctx.People.Include(x => x.Address).First();
    //p.Address IS NOT NULL!
    p.Address = null;
    var entry = ctx.Entry(p);
}

You could also use foreign keys in your model, which I like very much :

public class Person
{
    public int Id { get; set; }

    public string Name { get; set; }

    public virtual Address Address { get; set; }

    public int? AddressId {get; set;}
}

...

using (var ctx = new EFContext())
{
    Person p = ctx.People.First();
    p.AddressId = null;
    var entry = ctx.Entry(p);
}