/// <summary>
/// Toggles the given nodes expanded state.
/// </summary>
/// <param name="node">The node to be expanded or collapsed.</param>
public async Task ToggleNodeIsExpandedAsync(TreeNode <TItem> node)
{
var wasExpanded = node.IsExpanded;
// if expanding and Nodes is null then request data
if (!node.Isleaf && !wasExpanded && node.Nodes == null)
{
// fetch direct child items
var key = node.Data is null ? null : KeyField !(node.Data !).ToString();
var items = await GetDataAsync(key).ConfigureAwait(true);
// add new nodes to existing node
node.Nodes = new List <TreeNode <TItem> >(); // indicates data fetched, even if no items returned
UpdateModel(items);
// notify any listeners that new data fetched
await NodeUpdated.InvokeAsync(node).ConfigureAwait(true);
}
// expand / collapse and notify
node.IsExpanded = !wasExpanded;
if (wasExpanded)
{
await NodeCollapsed.InvokeAsync(node).ConfigureAwait(true);
}
else
{
await NodeExpanded.InvokeAsync(node).ConfigureAwait(true);
}
}
protected void OnNodeExpanded()
{
NodesExpandedCount++;
NodeExpanded?.Invoke(null, null);
}
