Unable to update Foreign Key in Entity Framework 6

c# entity-framework entity-framework-6.1 foreign-keys

Question

I am trying to do a simple update to the foreign key but the script never get sent over.

Here is the code I am using:

using (var db = new MyContext())
{
      db.Entry<Contact>(newContact).State = EntityState.Modified;
      newContact.ContactOwner = db.Person.Find(3);
      db.SaveChanges();
}

EF6 update the rest of the column in the Persons table but it is not updating the Contact_Id in Persons table.

Person entity:

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<Contact> ContactList { get; set; }
}

Contact entity:

public class Contact
{
    public int Id { get; set; }
    public string Email { get; set; }
    public string TelNo { get; set; }
    public Person ContactOwner { get; set; }
}

What am I missing here?

Please help!

1
6
8/21/2014 4:11:37 AM

Accepted Answer

Since you are working with independent association. You can either

  • Adding and removing the relationship from ContactList, but you need to retrieve from both Person.

    db.Entry(newContact).State = EntityState.Modified;
    
    var p1 = db.Set<Person>().Include(p => p.ContactList)
        .FirstOrDefault(p =>p.Id == 1);
    p1.ContactList.Remove(newContact);
    
    var p3 = db.Set<Person>().Include(p => p.ContactList)
        .FirstOrDefault(p => p.Id == 3);
    p3.ContactList.Add(newContact);
    
    db.SaveChanges();
    
  • Or you can use disconnected object, but you need to manually manage the relationship.

    db.Entry(newContact).State = EntityState.Modified;
    
    var p1 = new Person { Id = 1 };
    db.Entry(p1).State = EntityState.Unchanged;
    var p3 = new Person { Id = 3 };
    db.Entry(p3).State = EntityState.Unchanged;
    
    var manager = ((IObjectContextAdapter)db).ObjectContext.ObjectStateManager;
    manager.ChangeRelationshipState(newContact, p1, item => item.ContactOwner,
         EntityState.Deleted);
    manager.ChangeRelationshipState(newContact, p3, item => item.ContactOwner,
         EntityState.Added);
    
    db.SaveChanges();
    

PS

You might need to reconsider adding foreign key value, to make everything easier, updating foreign key just by mentioning the Id.

See this post for more information.

8
5/23/2017 12:02:36 PM

Popular Answer

Basically this happens because EntryState.Modified just looks for scalar properties (primitive types) and with independent association (your case) you don't have it.

There is a several ways to achieve this, @Yuliam has pointed some of them and here you can find more.



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