Recipe Book: No Favorites Yet

Part of the Lists and Screens section of Coddy's Flutter journey. Lesson 33 of 33.

Open the Favorites tab before hearting anything: the screen is blank, and a blank screen looks broken. An empty list should say why it is empty.

A list's isEmpty is true when it has no items. Choose the page in build with an if, before the return:

Widget page;
if (index == 0) {
  page = recipeList(recipes);
} else if (favorites.isEmpty) {
  page = const Center(child: Text('No favorites yet'));
} else {
  page = recipeList(favorites);
}

A variable of type Widget can hold any widget, so page is a list on one branch and a message on another. The Scaffold's body is then page.

Challenge

Easy

When the Favorites tab has nothing to show, show No favorites yet in the middle of the screen, size 18, in place of the empty list. Once a recipe is hearted, the tab lists it again.

Try it yourself

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomeScreen(),
    );
  }
}

class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  final List<Recipe> recipes = [
    Recipe(name: 'Pancakes', minutes: 20, ingredients: ['Flour', 'Eggs', 'Milk', 'Butter']),
    Recipe(name: 'Tomato Soup', minutes: 35, ingredients: ['Tomatoes', 'Onion', 'Garlic', 'Olive oil']),
    Recipe(name: 'Guacamole', minutes: 10, ingredients: ['Avocados', 'Lime', 'Onion', 'Salt']),
    Recipe(name: 'Fried Rice', minutes: 25, ingredients: ['Rice', 'Eggs', 'Peas', 'Soy sauce']),
  ];
  int index = 0;

  Widget recipeList(List<Recipe> shown) {
    return ListView.builder(
      itemCount: shown.length,
      itemBuilder: (context, i) {
        final Recipe recipe = shown[i];
        return ListTile(
          leading: const Icon(Icons.restaurant_menu),
          title: Text(recipe.name),
          subtitle: Text('${recipe.minutes} min'),
          onTap: () {
            Navigator.push(
              context,
              MaterialPageRoute(builder: (context) => RecipeScreen(recipe: recipe)),
            );
          },
          trailing: IconButton(
            icon: Icon(
              recipe.favorite ? Icons.favorite : Icons.favorite_border,
              color: recipe.favorite ? Colors.red : null,
            ),
            onPressed: () {
              setState(() {
                recipe.favorite = !recipe.favorite;
              });
            },
          ),
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    final List<Recipe> favorites = recipes.where((recipe) => recipe.favorite).toList();
    return Scaffold(
      appBar: AppBar(title: const Text('Recipe Book')),
      body: index == 0 ? recipeList(recipes) : recipeList(favorites),
      bottomNavigationBar: NavigationBar(
        selectedIndex: index,
        onDestinationSelected: (int i) {
          setState(() {
            index = i;
          });
        },
        destinations: const [
          NavigationDestination(
            icon: Icon(Icons.menu_book_outlined),
            selectedIcon: Icon(Icons.menu_book),
            label: 'Recipes',
          ),
          NavigationDestination(
            icon: Icon(Icons.star_border),
            selectedIcon: Icon(Icons.star),
            label: 'Favorites',
          ),
        ],
      ),
    );
  }
}

class RecipeScreen extends StatelessWidget {
  const RecipeScreen({super.key, required this.recipe});

  final Recipe recipe;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(recipe.name)),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: [
          Text('Ready in ${recipe.minutes} minutes', style: const TextStyle(fontSize: 18)),
          const SizedBox(height: 24),
          const Text('Ingredients', style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
          for (String ingredient in recipe.ingredients)
            ListTile(
              leading: const Icon(Icons.check_circle_outline),
              title: Text(ingredient),
            ),
        ],
      ),
    );
  }
}

class Recipe {
  final String name;
  final int minutes;
  final List<String> ingredients;
  bool favorite = false;

  Recipe({required this.name, required this.minutes, required this.ingredients});
}