1. @override
Future onInvoke(Map<String, dynamic> params)

This is called when this node is invoked. You can return the following types from this method:

  • Iterable
  • Map
  • Table
  • Stream
  • SimpleTableResult
  • AsyncTableResult

You can also return a future that resolves to one (like if the method is async) of the following types:

  • Stream
  • Iterable
  • Map
  • Table

Source 

@override
onInvoke(Map<String, dynamic> params) async {
  TimeRange tr = parseTimeRange(params["timeRange"]);
  if (tr == null) {
    return;
  }

  WatchGroupNode watchGroupNode = _link[new Path(path).parentPath];
  await watchGroupNode.db.database.purgeGroup(
    watchGroupNode._watchName,
    tr
  );
}