MobX is a state management library that makes it simple to connect the reactive data of your application with the UI. This article explores how to use MobX effectively in Flutter applications.

Why MobX?

MobX provides a simple and scalable approach to state management based on three core concepts:

• Observables — the reactive state of your application
• Actions — anything that modifies state
• Reactions — the observers that notify you when state changes

Getting Started

Add the required dependencies to your pubspec.yaml:

dependencies:
  mobx: ^2.0.0
  flutter_mobx: ^2.0.0

dev_dependencies:
  build_runner: ^2.0.0
  mobx_codegen: ^2.0.0

Defining a Store

import 'package:mobx/mobx.dart';

part 'counter_store.g.dart';

class CounterStore = _CounterStore with _$CounterStore;

abstract class _CounterStore with Store {
  @observable
  int count = 0;

  @action
  void increment() {
    count++;
  }
}

Using the Store in Widgets

Wrap your widget with Observer to reactively rebuild when observables change:

Observer(
  builder: (_) => Text('Count: ${store.count}'),
)

MobX handles the subscription and disposal automatically — no manual stream management needed.

When to Use MobX

MobX is well-suited for applications where you want a straightforward, boilerplate-light approach to state management. It shines in form-heavy UIs and apps with complex derived state.

For larger applications with strict architecture requirements, consider combining MobX with a layered architecture or evaluating alternatives like Riverpod.