Bloc (State Management) Items Add to Cart Functionality in List Example

import "dart:async";
import "package:flutter/material.dart";

class Todo
{
  final String title;
  bool completed;
  Todo(this.title, {this.completed = false});
}
class TodoBloc
{
  final _todoController = StreamController<List<Todo>>.broadcast();
  final List<Todo> _todos = [];

  Stream<List<Todo>> get todoStream {
    return _todoController.stream;
  }

  void addTodo(Todo todo)
  {
    _todos.add(todo);
    _todoController.sink.add(_todos);
  }

  void toggleTodoCompletion(int index)
  {
    _todos[index].completed = !_todos[index].completed;
    _todoController.sink.add(_todos);
  }

  void dispose()
  {
    _todoController.close();
  }
}

void main()
{
  runApp(const MyApp());
}
class MyApp extends StatelessWidget
{
  const MyApp({super.key});
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: "Todo AddToCart App",
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.grey,
      ),
      home: const AddToCart(),
    );
  }
}
class AddToCart extends StatefulWidget
{
  const AddToCart({super.key});
  @override
  State<AddToCart> createState()
  {
    return AddToCartState();
  }
}
class AddToCartState extends State<AddToCart>
{
  final TextEditingController _controller = TextEditingController();
  final TodoBloc _todoBloc = TodoBloc();
  final List<String> _cartItems = [];

  @override
  void dispose()
  {
    _controller.dispose();
    _todoBloc.dispose();
    super.dispose();
  }

  void addToCart(String items)
  {
    setState(() {
      _cartItems.add(items);
    },);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Todo App"),
        centerTitle: true,
        backgroundColor: Colors.grey,
      ),
      body: StreamBuilder<List<Todo>>(
        stream: _todoBloc.todoStream,
        builder: (context, snapshot) {
          return ListView.builder(
            itemCount: snapshot.data?.length ?? 0,
            itemBuilder: (context, index) {
              final todo = snapshot.data![index];
              return Card(
                child: ListTile(
                  leading: CircleAvatar(child: Text(todo.title[0]),),
                  title: Text(todo.title,
                    style: TextStyle(decoration: todo.completed ? TextDecoration.lineThrough : null),
                  ),
                  subtitle: Text(todo.title),
                  trailing: IconButton(
                    icon: Icon(todo.completed ? Icons.check_box : Icons.check_box_outline_blank),
                    onPressed: () {
                      _todoBloc.toggleTodoCompletion(index);
                    },
                  ),
                  onTap: () {
                    addToCart(todo.title);
                    ScaffoldMessenger.of(context).showSnackBar(
                      SnackBar(content: Text("Added ${todo.title}"),),
                    );
                  },
                ),
              );
            },
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          showDialog(
            context: context,
            builder: (context) {
              return AlertDialog(
                title: const Text("Add data"),
                content: TextFormField(
                  controller: _controller,
                  decoration: const InputDecoration(
                    hintText: "Enter the data",
                  ),
                ),
                actions: <Widget>[
                  ElevatedButton(
                    onPressed: () {
                      _todoBloc.addTodo(Todo(_controller.text));
                      _controller.clear();
                      Navigator.pop(context);
                    },
                    child: const Text("Add", style: TextStyle(fontWeight: FontWeight.bold),),
                  ),
                ],
              );
            },
          );
        },
        backgroundColor: Colors.blue,
        child: const Icon(Icons.add, color: Colors.white, size: 30.0),
      ),
      persistentFooterButtons: [
        ElevatedButton(
          onPressed: () {
            Navigator.push(
              context,
              MaterialPageRoute(
                builder: (context) {
                  return CartPage2(cartItems: _cartItems);
                },
              ),
            );
          },
          child: const Text("Open Cart"),
        ),
      ],
    );
  }
}
class CartPage2 extends StatelessWidget
{
  CartPage2({super.key, required this.cartItems});

  final List<String> cartItems;
  final TextEditingController _controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Cart Items"),
        centerTitle: true,
        backgroundColor: Colors.grey,
      ),
      body: ListView.builder(
        itemCount: cartItems.length,
        itemBuilder: (context, index) {
          return Card(
            child: ListTile(
              title: Text(cartItems[index]),
              subtitle: Text(cartItems[index]),
              trailing: Row(
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  IconButton(
                    onPressed: () {
                      showDialog(
                        context: context,
                        builder: (context) {
                          return AlertDialog(
                            title: const Text("Edit data"),
                            content: TextFormField(
                              controller: _controller,
                              decoration: const InputDecoration(
                                hintText: "Edit data",
                              ),
                            ),
                            actions: <Widget>[
                              TextButton(
                                onPressed: () {
                                  Navigator.pop(context);
                                },
                                child: const Text("Edit",
                                  style: TextStyle(fontWeight: FontWeight.bold),
                                ),
                              ),
                            ],
                          );
                        },
                      );
                    },
                    icon: const Icon(Icons.edit),
                  ),
                  IconButton(
                    onPressed: () {
                      showDialog(
                        context: context,
                        builder: (context) {
                          return AlertDialog(
                            title: const Text("Delete data ?",
                              style: TextStyle(fontWeight: FontWeight.bold),
                            ),
                            content: const Text("Are you sure to delete data ?"),
                            actions: <Widget>[
                              TextButton(
                                onPressed: () {
                                  Navigator.pop(context);
                                },
                                child: const Text("No",
                                  style: TextStyle(fontWeight: FontWeight.bold),
                                ),
                              ),
                              TextButton(
                                onPressed: () {
                                  Navigator.pop(context);
                                },
                                child: const Text("Yes",
                                  style: TextStyle(fontWeight: FontWeight.bold),
                                ),
                              ),
                            ],
                          );
                        },
                      );
                    },
                    icon: const Icon(Icons.delete),
                  ),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}