Update and Add Child Rows at same time with Entity Framework

Question

i´m having some troubles when it comes to modify and add child rows at the same time. I´m using the technique from the answer: stackoverflow.com/questions/5557829/....

The problem is in the following code:

public void EditReport(tbl_inspection inspection)
{
    foreach (var roll in inspection.tbl_inspection_roll)
    {                    
        container.tbl_inspection_roll.Attach(roll);
        container.ObjectStateManager.ChangeObjectState(roll, (roll.id_inspection_roll == 0) ? EntityState.Added : EntityState.Modified);
    }

    container.SaveChanges();
}

I always have at least 1 row to update. When I have 1 row to add, it works fine, the problem is when I try to add more than 1 row at the same time, shows the well-known error:

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

Feels like I´m missing something here...

Answer 1

I think that you need to split off the modified from the added. In the question that you linked to Ladislav had the following code as an example of this:

if (myEntity.Id != 0)
{
    context.MyEntities.Attach(myEntity);
    context.ObjectStateManager.ChangeObjectState(myEntity, EntityState.Modified);
}
else
{
    context.MyEntities.AddObject(myEntity);
}

context.SaveChanges();

I think that using Attach specifically, instead of using AddObject is what's causing the error.

EDIT: Try the following for the Attach part instead:

var r = new tbl_inspection_roll { id_inspection_roll = roll.id_inspection_roll };
container.tbl_inspection_roll.Attach(r);
container.Entry(r).CurrentValues.SetValues(roll);