public override void Update <T>(IChangeTracker changeTracker, IEntityManager entityManager, T existing, T entity)
{
var innerElementType = GetCollectionElementType();
var updateValues = GetValue <IEnumerable>(entity) ?? new List <object>();
var dbCollection = GetValue <IEnumerable>(existing) ?? CreateMissingCollection(existing, innerElementType);
var dbHash = dbCollection.Cast <object>().ToDictionary(item => entityManager.CreateEntityKey(item));
// Iterate through the elements from the updated graph and try to match them against the db graph
var updateList = updateValues.OfType <object>().ToList();
for (int i = 0; i < updateList.Count; i++)
{
var updateItem = updateList[i];
var key = entityManager.CreateEntityKey(updateItem);
// try to find item with same key in db collection
object dbItem;
if (dbHash.TryGetValue(key, out dbItem))
{
UpdateElement(changeTracker, entityManager, existing, updateItem, dbItem);
dbHash.Remove(key);
}
else
{
updateList[i] = AddElement(changeTracker, entityManager, existing, updateItem, dbCollection);
}
}
// remove obsolete items
foreach (var dbItem in dbHash.Values)
{
RemoveElement(changeTracker, dbItem, dbCollection);
}
}