OnWillChangeCallback<ViewModel> typedef

OnWillChangeCallback<ViewModel> = void Function(ViewModel? previousViewModel, ViewModel newViewModel)

A function that will be run on State change, before the build method.

This function is passed the previous and current ViewModel, and if distinct is true, it will only be called when the ViewModel changes.

This is useful for making calls to other classes, such as a Navigator or TabController, in response to state changes. It can also be used to trigger an action based on the previous state.

StoreConnector<String, String>(
  converter: (store) => store.state,
  onWillChange: (prev, vm) {
    if (prev != vm) {
      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
        content: Text(vm),
      ));
    }
  },
  builder: (context, vm) {
    return Text(vm);
  },
);

Implementation

typedef OnWillChangeCallback<ViewModel> = void Function(
  ViewModel? previousViewModel,
  ViewModel newViewModel,
);