使用Riverpod在Flutter中创建Todo列表

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
 
// 定义Todo模型
class Todo {
  final String title;
  final bool completed;
 
  Todo(this.title, this.completed);
}
 
// 定义Todo模型的StateNotifier，用于管理Todo列表状态
class TodosNotifier extends StateNotifier<List<Todo>> {
  TodosNotifier() : super([]);
 
  void addTodo(String title) {
    state = [...state, Todo(title, false)];
  }
 
  void removeTodo(Todo todo) {
    state = state.where((element) => element != todo).toList();
  }
 
  void toggleTodo(Todo todo) {
    state = state.map((t) {
      if (t == todo) {
        return Todo(t.title, !t.completed);
      }
      return t;
    }).toList();
  }
}
 
// 使用StateNotifierProvider来提供TodosNotifier的实例
final todosProvider = StateNotifierProvider<TodosNotifier, List<Todo>>((ref) {
  return TodosNotifier();
});
 
// 创建TodoList视图
class TodoList extends ConsumerWidget {
  const TodoList({Key? key}) : super(key: key);
 
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final todos = ref.watch(todosProvider);
 
    return ListView.builder(
      itemCount: todos.length,
      itemBuilder: (context, index) {
        final todo = todos[index];
        return CheckboxListTile(
          title: Text(todo.title),
          value: todo.completed,
          onChanged: (value) {
            ref.read(todosProvider.notifier).toggleTodo(todo);
          },
        );
      },
    );
  }
}
 
void main() {
  runApp(const ProviderScope(child: TodoApp()));
}
 
class TodoApp extends StatelessWidget {
  const TodoApp({Key? key}) : super(key: key);
 
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: const [
              Padding(
                padding: EdgeInsets.all(16.0),
                child: TodoList(),
              ),
            ],
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            Navigator.of(context).push(MaterialPageRoute(
              builder: (context) => const AddTodoScreen(),
            ));
          },
          child: const Icon(Icons.add),
        ),
      ),
    );
  }
}
 
class AddTodoScreen extends ConsumerStatefulWidget {
  const AddTodoScreen({Key? key}) : super(key: key);
 
  @override
  _