crizant / change_notifier_builder

A widget builder whose content stays synced with one or more `ChangeNotifier`s.

DEPRECATED

Please migrate to ListenableBuilder or MultiListenableBuilder instead.

change_notifier_builder

A widget builder whose content stays synced with one or more ChangeNotifiers.

What is this?

Many of us flutter developers use ChangeNotifier for state management, but there is no such thing as ChangeNotifierBuilder.

This is basically an AnimatedBuilder provided by flutter sdk, with a few minor modifitcations. Actually you might use AnimatedBuilder instead.

Why you created this?

I created this package for 4 reasons.

1. For the purpose of state management, ChangeNotifierBuilder is a more reasonable and readable name than AnimatedBuilder, for a builder widget.

2. Sometimes our model is not yet ready (i.e. equals null). In this case if you use AnimatedBuilder it throws "animation cannot be null" exception. However if you use ChangeNotifierBuilder, the runtime value of notifier can be null.

3. The builder method provides you the T notifier object as a parameter, which is a bit more user-friendly.

4. You can’t listen to multiple ChangeNotifiers with AnimatedBuilder, so I created MultiChangeNotifierBuilder for this purpose.

Example

Let's say you have a model of ChangeNotifier like this:

class CounterModel extends ChangeNotifier {
  int _count = 0;

  void increment() {
    _count++;
    notifyListeners();
  }

  int get count => _count;
}

Then in the build method of your widget:

ChangeNotifierBuilder(
  // supply the instance of `ChangeNotifier` model,
  // whether you get it from the build context or anywhere
  notifier: _counterModel,
  // this builder function will be executed,
  // once the `ChangeNotifier` model is updated
  builder: (BuildContext context, CounterModel? counter, _) {
    return Text(
      '${counter?.count ?? ''}',
      style: Theme.of(context).textTheme.headline4,
    );
  },
)

Want to listen to a list of ChangeNotifiers?

Use MultiChangeNotifierBuilder instead!

Contributions

Feel free to contribute to this project.

If you find a bug or want a feature, but don't know how to fix/implement it, please fill an issue. If you fixed a bug or implemented a feature, please send a pull request.