/// <summary>
/// Creates the or update array map.
/// </summary>
protected virtual void CreateOrUpdateArrayMap(object viewModel, PropertyInfo parentProperty, ref ViewModelMapNode map)
{
if (map == null)
{
map = new ViewModelMapArrayNode();
}
if (map is ViewModelMapArrayNode)
{
var itemValues = ((IEnumerable)viewModel).OfType<object>().ToList();
var typedMap = (ViewModelMapArrayNode)map;
// if the collection can be compared and updated by some property key, do it, otherwise replace the collection contents;
// the synchronization can only occur when there is a key map or when the collection is empty
var keyName = ResolveCollectionKeyName(parentProperty);
if (!string.IsNullOrEmpty(keyName) && typedMap.Items.Count == typedMap.KeyMap.Count)
{
SynchronizeCollections(typedMap, itemValues, keyName);
}
else
{
// replace collection contents
typedMap.Items.Clear();
typedMap.Items.AddRange(itemValues.Select(i => CreateMap(i, null)));
typedMap.KeyMap.Clear();
}
}
else
{
throw new Exception(string.Format("The viewModel is a collection or array but the {0} was expected.", map.GetType()));
}
}
/// <summary>
/// Synchronizes the collections using specified key property.
/// </summary>
private void SynchronizeCollections(ViewModelMapArrayNode targetArray, IEnumerable<object> sourceItems, string keyName)
{
var sourceKeyMap = sourceItems.ToDictionary(i => i.GetType().GetProperty(keyName).GetValue(i).ToString());
var targetKeyMap = targetArray.KeyMap;
// detect changes
var newItems = sourceKeyMap.Keys.Except(targetKeyMap.Keys).ToList();
var updatedItems = targetKeyMap.Keys.Intersect(sourceKeyMap.Keys).ToList();
var removedItems = targetKeyMap.Keys.Except(sourceKeyMap.Keys).ToList();
// add items
foreach (var newItem in newItems)
{
var item = CreateMap(sourceKeyMap[newItem], null);
targetArray.Items.Add(item);
targetKeyMap[newItem] = item;
}
// update items
foreach (var updatedItem in updatedItems)
{
var sourceItem = sourceKeyMap[updatedItem];
var targetItem = targetKeyMap[updatedItem];
CreateOrUpdateMap(sourceItem, null, ref targetItem);
}
// remove items
foreach (var removedItem in removedItems)
{
var item = targetKeyMap[removedItem];
targetArray.Items.Remove(item);
targetKeyMap.Remove(removedItem);
}
}