Object structure, problems with updating related objects

Question

I am currently working on a project using the latest version of the Entity Framework, and I ran into a problem that I seem to be unable to solve.

When it comes to updating existing objects, I can pretty easily update the properties of the ok object until I get to a property that is a reference to another class.

In the example below, I have a class Foo that stores various properties, and 2 of them are instances of other classes

public class Foo { public int Id {get; set;} public string Name {get; set;} public SubFoo SubFoo {get; set} public AnotherSubFoo AnotherSubFoo {get; set} } 

When I use the Edit() method below, I go through the object I would like to update, and I can manage to get the Name to update correctly, however I could not find a way in which to get the SubFoo property into change. For example, if the SubFoo class has a Name property, and it has been changed and differs from my DB and newFoo , it is not updated.

 public Foo Edit(Foo newFoo) { var dbFoo = context.Foo .Include(x => x.SubFoo) .Include(x => x.AnotherSubFoo) .Single(c => c.Id == newFoo.Id); var entry = context.Entry<Foo>(dbFoo); entry.OriginalValues.SetValues(dbFoo); entry.CurrentValues.SetValues(newFoo); context.SaveChanges(); return newFoo; } 

Any help or pointers would be greatly appreciated.

UPDATE: Based on Slauma's comment, I changed my method to

 public Foo Edit(Foo newFoo) { var dbFoo = context.Foo .Include(x => x.SubFoo) .Include(x => x.AnotherSubFoo) .Single(c => c.Id == newFoo.Id); context.Entry(dbFoo).CurrentValues.SetValues(newFoo); context.Entry(dbFoo.SubFoo).CurrentValues.SetValues(newFoo.SubFoo); context.SaveChanges(); return newFoo; } 

When you run this now, I get an error message:

The object type Collection'1 is not part of the model for the current context.

To try to get around this, I added code to try to subclass newFoo in the context, but this is with an error saying that the ObjectManager already had an entity:

An object with the same key already exists in the ObjectStateManager. ObjectStateManager cannot track multiple objects with the same key

Answer 1

CurrentValues.SetValues only updates scalar properties, but has no related objects, so you should do the same for each related object:

 public Foo Edit(Foo newFoo) { var dbFoo = context.Foo .Include(x => x.SubFoo) .Include(x => x.AnotherSubFoo) .Single(c => c.Id == newFoo.Id); context.Entry(dbFoo).CurrentValues.SetValues(newFoo); context.Entry(dbFoo.SubFoo).CurrentValues.SetValues(newFoo.SubFoo); context.Entry(dbFoo.AnotherSubFoo).CurrentValues.SetValues(newFoo.AnotherSubFoo); context.SaveChanges(); return newFoo; } 

If the connection could be completely deleted or was created, you also need to explicitly handle these cases:

 public Foo Edit(Foo newFoo) { var dbFoo = context.Foo .Include(x => x.SubFoo) .Include(x => x.AnotherSubFoo) .Single(c => c.Id == newFoo.Id); context.Entry(dbFoo).CurrentValues.SetValues(newFoo); if (dbFoo.SubFoo != null) { if (newFoo.SubFoo != null) { if (dbFoo.SubFoo.Id == newFoo.SubFoo.Id) // no relationship change, only scalar prop. context.Entry(dbFoo.SubFoo).CurrentValues.SetValues(newFoo.SubFoo); else { // Relationship change // Attach assumes that newFoo.SubFoo is an existing entity context.SubFoos.Attach(newFoo.SubFoo); dbFoo.SubFoo = newFoo.SubFoo; } } else // relationship has been removed dbFoo.SubFoo = null; } else { if (newFoo.SubFoo != null) // relationship has been added { // Attach assumes that newFoo.SubFoo is an existing entity context.SubFoos.Attach(newFoo.SubFoo); dbFoo.SubFoo = newFoo.SubFoo; } // else -> old and new SubFoo is null -> nothing to do } // the same logic for AnotherSubFoo ... context.SaveChanges(); return newFoo; } 

Ultimately, you also need to set the state of the attached objects to Modified if the relation has been changed and scalar properties as well.

Edit

If - according to your comment - Foo.SubFoo is actually a compilation, not just a link, you will need something similar to update related objects:

 public Foo Edit(Foo newFoo) { var dbFoo = context.Foo .Include(x => x.SubFoo) .Include(x => x.AnotherSubFoo) .Single(c => c.Id == newFoo.Id); // Update foo (works only for scalar properties) context.Entry(dbFoo).CurrentValues.SetValues(newFoo); // Delete subFoos from database that are not in the newFoo.SubFoo collection foreach (var dbSubFoo in dbFoo.SubFoo.ToList()) if (!newFoo.SubFoo.Any(s => s.Id == dbSubFoo.Id)) context.SubFoos.Remove(dbSubFoo); foreach (var newSubFoo in newFoo.SubFoo) { var dbSubFoo = dbFoo.SubFoo.SingleOrDefault(s => s.Id == newSubFoo.Id); if (dbSubFoo != null) // Update subFoos that are in the newFoo.SubFoo collection context.Entry(dbSubFoo).CurrentValues.SetValues(newSubFoo); else // Insert subFoos into the database that are not // in the dbFoo.subFoo collection dbFoo.SubFoo.Add(newSubFoo); } // and the same for AnotherSubFoo... db.SaveChanges(); return newFoo; } 

Answer 2

Just thought I'd post the link below, as it really helped me understand how to update related objects.

Updating entity infrastructure related data in an asp net mvc application

NOTE. I slightly changed the logic that is shown in the UpdateInstructorCourses function according to my needs.

Answer 3

You can also call tables yourself

 MyContext db = new MyContext // I like using asynchronous calls in my API methods var OldFoo = await db.Foo.FindAsync(id); var OldAssociateFoo = db.AssociatedFoo; var NewFoo = OldFoo; var NewAssociatedFoo = OldAssociatedFoo; NewFoo.SomeValue = "The Value"; NewAssociatedFoo.OtherValue = 20; db.Entry(OldFoo).CurrentValues.SetValues(NewFoo); db.Entry(OldAssociatedFoo).CurrentValues.SetValues(NewAssociatedFoo); await db.SaveChangesAsync();