fromAncestor<D, DAncestor> static method

Creates an InitialData that produces its initial value by calling initialValue with a value of type DAncestor, obtained by from an ancestor state in the state tree.

class ParentData {
  String value = '';
  ParentData(this.value);
}
var parentState = StateKey('parent');
var childState = StateKey('child');
var builder = StateTreeBuilder(initialState: parentState);

builder.dataState<ParentData>(
  parentState,
  InitialData.value(ParentData('parent value')),
  (_) {},
  initialChild: childState);

builder.dataState<int>(
  childState,
  // Initialize the state data for the child state from the state data of
  // the parent state
  InitialData.fromAncestor((ParentData ancestorData) => ancestorData.length),
  (_) {},
  parent: parentState
);