Failed to update foreign key in Entity Framework 6

Question

I am trying to do a simple foreign key update, but the script will never be sent.

Here is the code I'm using:

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

EF6 updates the rest of the column in the Persons table, but does not update the Contact_Id in Persons table.

Personality:

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

The contact person:

 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!

Answer 1

Because you are working with an independent association. You can either

• Adding and removing relationships from ContactList , but you need to get from 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 a disabled 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 may need to reconsider adding the foreign key value, make it easier, update the foreign key by simply specifying Id.

See this post for more details.

Answer 2

This is what I finished building until late in the morning, chould / should be reorganized yet ...

  protected static async Task<int> SaveEntity<t>(t obj) where t : BaseModel { try { using (DatabaseContext db = GetDbContext()) { //get the basemodel/fk reference properties IEnumerable<PropertyInfo> props = obj.GetType().GetProperties().Where(p => p.PropertyType.BaseType == typeof(BaseModel)); if (obj.Id <= 0) {//insert db.Entry(obj).State = EntityState.Added; //set fk reference props to unchanged state foreach (PropertyInfo prop in props) { Object val = prop.GetValue(obj); if (val != null) { db.Entry(val).State = EntityState.Unchanged; } } //do insert return await db.SaveChangesAsync(); } else {//update //get the posted fk values, and set them to null on the obj (to avaid dbContext conflicts) Dictionary<string, int?> updateFKValues = new Dictionary<string, int?>(); foreach (PropertyInfo prop in props) { BaseModel val = (BaseModel)prop.GetValue(obj); if (val == null) { updateFKValues.Add(prop.Name, null); } else { updateFKValues.Add(prop.Name, val.Id); } prop.SetValue(obj, null); } //dbContext creation may need to move to here as per below working example t dbObj = (t)db.Set(typeof(t)).Find(new object[] { obj.Id }); //this also differs from example //update the simple values db.Entry(dbObj).CurrentValues.SetValues(obj); //update complex values foreach (PropertyInfo prop in props) { Object propValue = null; if (updateFKValues[prop.Name].HasValue) { propValue = (BaseModel)db.Set(prop.PropertyType).Find(new object[] { updateFKValues[prop.Name] }); } prop.SetValue(dbObj, propValue); if (propValue != null) { db.Entry(propValue).State = EntityState.Unchanged; } } //do update return await db.SaveChangesAsync(); } } } catch (Exception ex) { ExceptionHelper.Log(ex); throw; } } 

Answer 3

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

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