fx_rx

A tiny reactive state management library for Flutter.

Features

• Rx<T>: reactive value for any type
• RxView(() => Widget): rebuilds automatically when Rx values used inside change
• RxList, RxMap, RxSet: reactive collections
• computed(() => ...): derived reactive values that update automatically
• select(() => ...): distinct derived values (notifies only when selected value changes)
• RxAsync<T>: simple async state (loading / data / error)
• Effects: ever(rx, ...), once(rx, ...), debounce(rx, ...), interval(rx, ...)
• batch(() { ... }): group multiple writes into a single notify wave

Install

Add to your pubspec.yaml:

dependencies:
  fx_rx: ^0.0.1

Quick start

import 'package:fx_rx/fx_rx.dart';

final count = Rx(0);

RxView(() => Text("Count: ${count.value}"));

void increment() => count.value++;

Extensions

final name = "John".rx; // Rx<String>
final age  = 30.rx;      // Rx<int>

Derived state (computed)

final first = "John".rx;
final last  = "Cena".rx;

final fullName = computed(() => "${first.value} ${last.value}");

RxView(() => Text(fullName.value));

Async state (RxAsync)

final users = RxAsync<List<String>>();

Future<void> load() async {
  await users.run(() async {
    await Future.delayed(const Duration(seconds: 1));
    return ["A", "B", "C"];
  });
}

RxView(() => users.when(
  idle: () => const Text("Idle"),
  loading: () => const CircularProgressIndicator(),
  data: (d) => Text("Users: ${d.length}"),
  error: (e) => Text("Error: $e"),
));

Reactive collections

final items = RxList<String>();

items.add("A");

RxView(() => Text("Total: ${items.length}"));

Effects

final disposer = ever(count, (v) {
  // do something when count changes
});

disposer.dispose(); // stop listening

Batch

batch(() {
  a.value = 1;
  b.value = 2;
});

License

MIT. See LICENSE.

Select (distinct derived)

final user = Rx({"name": "A", "age": 1});

// Only rebuild when "age" changes:
final age = select(() => user.value["age"]);

RxView(() => Text("Age: ${age.value}"));

More effects

once

final d = once(count, (v) {
  // runs once on first change
});
d.dispose();

debounce

final d = debounce(query, const Duration(milliseconds: 300), (v) => search(v));
d.dispose();

interval

final d = interval(scroll, const Duration(milliseconds: 200), (v) => log(v));
d.dispose();

Example app

A runnable Flutter example is included in example/.

cd example
flutter run