Material-tree displaying blank

[ouekalo]

I am looking why material-tree is displaying nothing. Here is my code

For Component

@Component( selector: 'tree-root', directives: [MaterialTreeComponent], templateUrl: 'tree_component.html', styleUrls: ['tree_component.css'], changeDetection: ChangeDetectionStrategy.OnPush, ) class TreeComponent {

final SelectionOptions nestedOptions = data.nestedOptions;

ItemRenderer childItemRenderer = (String childTitle)=>childTitle.toUpperCase();

String itemRenderer(item) =>childItemRenderer(item);

@ViewChild(MaterialTreeComponent) MaterialTreeComponent materialTree; }

For tree Options

final _commonParentChildrenMap = { 'Animated Feature Films': [ OptionGroup([ 'Cinderalla', 'Alice In Wonderland', 'Peter Pan', 'Lady and the Tramp', ]) ], 'Live-Action Films': [ OptionGroup( ['Treasure Island', 'The Littlest Outlaw', 'Old Yeller', 'Star Wars']) ], 'Documentary Films': [ OptionGroup(['Frank and Ollie', 'Sacred Planet']) ], 'Star Wars': [ OptionGroup(['By George Lucas']) ], 'By George Lucas': [ OptionGroup(['A New Hope', 'Empire Strikes Back', 'Return of the Jedi']) ] };

/// An example data set of hierarchical data. final SelectionOptions nestedOptions = _NestedSelectionOptions([ OptionGroup( ['Animated Feature Films', 'Live-Action Films', 'Documentary Films']) ], _commonParentChildrenMap);

/// A slight restructure of [nestedOptions] to separate "Animated Feature Films" /// with the other two option groups. final SelectionOptions nestedOptionsVariation = _NestedSelectionOptions([ OptionGroup(['Animated Feature Films']), OptionGroup(['Live-Action Films']), OptionGroup(['Documentary Films']), ], _commonParentChildrenMap);

/// An example implementation of [SelectionOptions] with [Parent]. class _NestedSelectionOptions extends SelectionOptions implements Parent<T, List<OptionGroup>> { final Map<T, List<OptionGroup>> _children;

_NestedSelectionOptions(List<OptionGroup> options, this._children) : super(options);

@override bool hasChildren(T item) => _children.containsKey(item);

@override DisposableFuture<List<OptionGroup>> childrenOf(T parent, [_]) { print("$_children"); return DisposableFuture<List<OptionGroup>>.fromValue(_children[parent]); } }

[TedSander]

Sorry going to need more information before we could even start looking at this. The examples for the tree are working that last time I checked.