select<Notifier, Result> method

@override Result select<Notifier, Result>(Target<Notifier, Result> target)

read a Notifier from one provider and subscribe the widget to the changes of this Notifier.

target is a value gotten from .select or .when

the widget only will be rebuilded depending of the condition of each method.

Implementation

@override
Result select<Notifier, Result>(Target<Notifier, Result> target) {
  // if the widget was rebuilded
  if (_isExternalBuild) {
    _clearDependencies();
  }
  _isExternalBuild = false;
  final notifier = target.notifier;

  final insideDependencies = _dependencies.containsKey(notifier);
  // if there is not a listener for the current provider
  if (!insideDependencies) {
    target.rebuild = _rebuild;
    if (notifier is StateNotifier) {
      if (target.filter == Filter.select) {
        createStateSelectListener(target);
      } else {
        throw FlutterError('.when filter only is allowed with ref.watch');
      }
    } else {
      createSimpleSelectListener(target);
    }

    final listener = target.listener;
    // add the listener to the current notifier
    _dependencies[notifier as BaseNotifier] = listener;
    _targets[notifier] = target;
    (notifier as ListeneableNotifier).addListener(listener);
  }
  return _targets[notifier]!.selectValue; // coverage:ignore-line
}