CRUD Operations

Complete examples of implementing CRUD (Create, Read, Update, Delete) operations with Fasq. Learn how to build a full-featured data management interface.

Basic CRUD Setup

Data Models

class User {
  final String id;
  final String name;
  final String email;
  final DateTime createdAt;
  final DateTime updatedAt;

  User({
    required this.id,
    required this.name,
    required this.email,
    required this.createdAt,
    required this.updatedAt,
  });

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      id: json['id'],
      name: json['name'],
      email: json['email'],
      createdAt: DateTime.parse(json['createdAt']),
      updatedAt: DateTime.parse(json['updatedAt']),
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'name': name,
      'email': email,
      'createdAt': createdAt.toIso8601String(),
      'updatedAt': updatedAt.toIso8601String(),
    };
  }

  User copyWith({
    String? id,
    String? name,
    String? email,
    DateTime? createdAt,
    DateTime? updatedAt,
  }) {
    return User(
      id: id ?? this.id,
      name: name ?? this.name,
      email: email ?? this.email,
      createdAt: createdAt ?? this.createdAt,
      updatedAt: updatedAt ?? this.updatedAt,
    );
  }
}

class Post {
  final String id;
  final String title;
  final String content;
  final String authorId;
  final DateTime createdAt;
  final DateTime updatedAt;

  Post({
    required this.id,
    required this.title,
    required this.content,
    required this.authorId,
    required this.createdAt,
    required this.updatedAt,
  });

  factory Post.fromJson(Map<String, dynamic> json) {
    return Post(
      id: json['id'],
      title: json['title'],
      content: json['content'],
      authorId: json['authorId'],
      createdAt: DateTime.parse(json['createdAt']),
      updatedAt: DateTime.parse(json['updatedAt']),
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'title': title,
      'content': content,
      'authorId': authorId,
      'createdAt': createdAt.toIso8601String(),
      'updatedAt': updatedAt.toIso8601String(),
    };
  }

  Post copyWith({
    String? id,
    String? title,
    String? content,
    String? authorId,
    DateTime? createdAt,
    DateTime? updatedAt,
  }) {
    return Post(
      id: id ?? this.id,
      title: title ?? this.title,
      content: content ?? this.content,
      authorId: authorId ?? this.authorId,
      createdAt: createdAt ?? this.createdAt,
      updatedAt: updatedAt ?? this.updatedAt,
    );
  }
}

API Service

class CrudApiService {
  static const String baseUrl = 'https://api.example.com';

  // Users CRUD
  static Future<List<User>> getUsers() async {
    final response = await http.get(Uri.parse('$baseUrl/users'));
    if (response.statusCode == 200) {
      final data = jsonDecode(response.body);
      return (data['users'] as List)
          .map((json) => User.fromJson(json))
          .toList();
    } else {
      throw Exception('Failed to fetch users');
    }
  }

  static Future<User> getUser(String id) async {
    final response = await http.get(Uri.parse('$baseUrl/users/$id'));
    if (response.statusCode == 200) {
      final data = jsonDecode(response.body);
      return User.fromJson(data['user']);
    } else {
      throw Exception('Failed to fetch user');
    }
  }

  static Future<User> createUser(Map<String, String> data) async {
    final response = await http.post(
      Uri.parse('$baseUrl/users'),
      headers: {'Content-Type': 'application/json'},
      body: jsonEncode(data),
    );
    if (response.statusCode == 201) {
      final responseData = jsonDecode(response.body);
      return User.fromJson(responseData['user']);
    } else {
      throw Exception('Failed to create user');
    }
  }

  static Future<User> updateUser(String id, Map<String, String> data) async {
    final response = await http.put(
      Uri.parse('$baseUrl/users/$id'),
      headers: {'Content-Type': 'application/json'},
      body: jsonEncode(data),
    );
    if (response.statusCode == 200) {
      final responseData = jsonDecode(response.body);
      return User.fromJson(responseData['user']);
    } else {
      throw Exception('Failed to update user');
    }
  }

  static Future<void> deleteUser(String id) async {
    final response = await http.delete(Uri.parse('$baseUrl/users/$id'));
    if (response.statusCode != 204) {
      throw Exception('Failed to delete user');
    }
  }

  // Posts CRUD
  static Future<List<Post>> getPosts() async {
    final response = await http.get(Uri.parse('$baseUrl/posts'));
    if (response.statusCode == 200) {
      final data = jsonDecode(response.body);
      return (data['posts'] as List)
          .map((json) => Post.fromJson(json))
          .toList();
    } else {
      throw Exception('Failed to fetch posts');
    }
  }

  static Future<Post> getPost(String id) async {
    final response = await http.get(Uri.parse('$baseUrl/posts/$id'));
    if (response.statusCode == 200) {
      final data = jsonDecode(response.body);
      return Post.fromJson(data['post']);
    } else {
      throw Exception('Failed to fetch post');
    }
  }

  static Future<Post> createPost(Map<String, String> data) async {
    final response = await http.post(
      Uri.parse('$baseUrl/posts'),
      headers: {'Content-Type': 'application/json'},
      body: jsonEncode(data),
    );
    if (response.statusCode == 201) {
      final responseData = jsonDecode(response.body);
      return Post.fromJson(responseData['post']);
    } else {
      throw Exception('Failed to create post');
    }
  }

  static Future<Post> updatePost(String id, Map<String, String> data) async {
    final response = await http.put(
      Uri.parse('$baseUrl/posts/$id'),
      headers: {'Content-Type': 'application/json'},
      body: jsonEncode(data),
    );
    if (response.statusCode == 200) {
      final responseData = jsonDecode(response.body);
      return Post.fromJson(responseData['post']);
    } else {
      throw Exception('Failed to update post');
    }
  }

  static Future<void> deletePost(String id) async {
    final response = await http.delete(Uri.parse('$baseUrl/posts/$id'));
    if (response.statusCode != 204) {
      throw Exception('Failed to delete post');
    }
  }
}

Users CRUD Interface

Users List Screen

class UsersListScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Users'),
        actions: [
          IconButton(
            icon: Icon(Icons.refresh),
            onPressed: () {
              QueryClient().invalidateQuery('users');
            },
          ),
        ],
      ),
      body: QueryBuilder<List<User>>(
        queryKey: 'users',
        queryFn: () => CrudApiService.getUsers(),
        builder: (context, state) {
          return state.when(
            loading: () => Center(child: CircularProgressIndicator()),
            error: (error, stack) => Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Text('Error: $error'),
                  ElevatedButton(
                    onPressed: () {
                      QueryClient().invalidateQuery('users');
                    },
                    child: Text('Retry'),
                  ),
                ],
              ),
            ),
            data: (users) => ListView.builder(
              itemCount: users.length,
              itemBuilder: (context, index) {
                final user = users[index];
                return UserTile(user: user);
              },
            ),
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => CreateUserScreen(),
            ),
          );
        },
        child: Icon(Icons.add),
      ),
    );
  }
}

class UserTile extends StatelessWidget {
  final User user;

  const UserTile({required this.user});

  @override
  Widget build(BuildContext context) {
    return Card(
      child: ListTile(
        title: Text(user.name),
        subtitle: Text(user.email),
        trailing: PopupMenuButton(
          itemBuilder: (context) => [
            PopupMenuItem(
              value: 'edit',
              child: Row(
                children: [
                  Icon(Icons.edit),
                  SizedBox(width: 8),
                  Text('Edit'),
                ],
              ),
            ),
            PopupMenuItem(
              value: 'delete',
              child: Row(
                children: [
                  Icon(Icons.delete, color: Colors.red),
                  SizedBox(width: 8),
                  Text('Delete', style: TextStyle(color: Colors.red)),
                ],
              ),
            ),
          ],
          onSelected: (value) {
            switch (value) {
              case 'edit':
                Navigator.push(
                  context,
                  MaterialPageRoute(
                    builder: (context) => EditUserScreen(user: user),
                  ),
                );
                break;
              case 'delete':
                _showDeleteDialog(context);
                break;
            }
          },
        ),
        onTap: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => UserDetailScreen(userId: user.id),
            ),
          );
        },
      ),
    );
  }

  void _showDeleteDialog(BuildContext context) {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text('Delete User'),
        content: Text('Are you sure you want to delete ${user.name}?'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: Text('Cancel'),
          ),
          TextButton(
            onPressed: () {
              Navigator.pop(context);
              _deleteUser(context);
            },
            child: Text('Delete', style: TextStyle(color: Colors.red)),
          ),
        ],
      ),
    );
  }

  void _deleteUser(BuildContext context) {
    MutationBuilder<void, String>(
      mutationFn: (id) => CrudApiService.deleteUser(id),
      options: MutationOptions(
        onSuccess: (_, id) {
          // Invalidate users list to refetch
          QueryClient().invalidateQuery('users');
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('User deleted successfully')),
          );
        },
        onError: (error) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('Failed to delete user: $error')),
          );
        },
      ),
      builder: (context, state) {
        return state.mutate(user.id);
      },
    );
  }
}

Create User Screen

class CreateUserScreen extends StatefulWidget {
  @override
  State<CreateUserScreen> createState() => _CreateUserScreenState();
}

class _CreateUserScreenState extends State<CreateUserScreen> {
  final _formKey = GlobalKey<FormState>();
  final _nameController = TextEditingController();
  final _emailController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Create User')),
      body: MutationBuilder<User, Map<String, String>>(
        mutationFn: (data) => CrudApiService.createUser(data),
        options: MutationOptions(
          onSuccess: (user) {
            // Invalidate users list to refetch
            QueryClient().invalidateQuery('users');
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(content: Text('User created successfully')),
            );
            Navigator.pop(context);
          },
          onError: (error) {
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(content: Text('Failed to create user: $error')),
            );
          },
        ),
        builder: (context, state) {
          return Padding(
            padding: const EdgeInsets.all(16.0),
            child: Form(
              key: _formKey,
              child: Column(
                children: [
                  TextFormField(
                    controller: _nameController,
                    decoration: InputDecoration(labelText: 'Name'),
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return 'Name is required';
                      }
                      return null;
                    },
                  ),
                  SizedBox(height: 16),
                  TextFormField(
                    controller: _emailController,
                    decoration: InputDecoration(labelText: 'Email'),
                    keyboardType: TextInputType.emailAddress,
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return 'Email is required';
                      }
                      if (!value.contains('@')) {
                        return 'Please enter a valid email';
                      }
                      return null;
                    },
                  ),
                  SizedBox(height: 24),
                  ElevatedButton(
                    onPressed: state.isLoading ? null : () {
                      if (_formKey.currentState!.validate()) {
                        state.mutate({
                          'name': _nameController.text,
                          'email': _emailController.text,
                        });
                      }
                    },
                    child: state.isLoading
                        ? CircularProgressIndicator()
                        : Text('Create User'),
                  ),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}

Edit User Screen

class EditUserScreen extends StatefulWidget {
  final User user;

  const EditUserScreen({required this.user});

  @override
  State<EditUserScreen> createState() => _EditUserScreenState();
}

class _EditUserScreenState extends State<EditUserScreen> {
  final _formKey = GlobalKey<FormState>();
  late final TextEditingController _nameController;
  late final TextEditingController _emailController;

  @override
  void initState() {
    super.initState();
    _nameController = TextEditingController(text: widget.user.name);
    _emailController = TextEditingController(text: widget.user.email);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Edit User')),
      body: MutationBuilder<User, Map<String, String>>(
        mutationFn: (data) => CrudApiService.updateUser(widget.user.id, data),
        options: MutationOptions(
          onSuccess: (user) {
            // Invalidate related queries
            QueryClient().invalidateQuery('users');
            QueryClient().invalidateQuery('user:${widget.user.id}');
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(content: Text('User updated successfully')),
            );
            Navigator.pop(context);
          },
          onError: (error) {
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(content: Text('Failed to update user: $error')),
            );
          },
        ),
        builder: (context, state) {
          return Padding(
            padding: const EdgeInsets.all(16.0),
            child: Form(
              key: _formKey,
              child: Column(
                children: [
                  TextFormField(
                    controller: _nameController,
                    decoration: InputDecoration(labelText: 'Name'),
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return 'Name is required';
                      }
                      return null;
                    },
                  ),
                  SizedBox(height: 16),
                  TextFormField(
                    controller: _emailController,
                    decoration: InputDecoration(labelText: 'Email'),
                    keyboardType: TextInputType.emailAddress,
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return 'Email is required';
                      }
                      if (!value.contains('@')) {
                        return 'Please enter a valid email';
                      }
                      return null;
                    },
                  ),
                  SizedBox(height: 24),
                  ElevatedButton(
                    onPressed: state.isLoading ? null : () {
                      if (_formKey.currentState!.validate()) {
                        state.mutate({
                          'name': _nameController.text,
                          'email': _emailController.text,
                        });
                      }
                    },
                    child: state.isLoading
                        ? CircularProgressIndicator()
                        : Text('Update User'),
                  ),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}

User Detail Screen

class UserDetailScreen extends StatelessWidget {
  final String userId;

  const UserDetailScreen({required this.userId});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('User Details')),
      body: QueryBuilder<User>(
        queryKey: 'user:$userId',
        queryFn: () => CrudApiService.getUser(userId),
        builder: (context, state) {
          return state.when(
            loading: () => Center(child: CircularProgressIndicator()),
            error: (error, stack) => Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Text('Error: $error'),
                  ElevatedButton(
                    onPressed: () {
                      QueryClient().invalidateQuery('user:$userId');
                    },
                    child: Text('Retry'),
                  ),
                ],
              ),
            ),
            data: (user) => Padding(
              padding: const EdgeInsets.all(16.0),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Card(
                    child: Padding(
                      padding: const EdgeInsets.all(16.0),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Text('Name: ${user.name}', style: TextStyle(fontSize: 18)),
                          SizedBox(height: 8),
                          Text('Email: ${user.email}'),
                          SizedBox(height: 8),
                          Text('ID: ${user.id}'),
                          SizedBox(height: 8),
                          Text('Created: ${user.createdAt}'),
                          SizedBox(height: 8),
                          Text('Updated: ${user.updatedAt}'),
                        ],
                      ),
                    ),
                  ),
                  SizedBox(height: 16),
                  ElevatedButton(
                    onPressed: () {
                      Navigator.push(
                        context,
                        MaterialPageRoute(
                          builder: (context) => EditUserScreen(user: user),
                        ),
                      );
                    },
                    child: Text('Edit User'),
                  ),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}

Posts CRUD Interface

Posts List Screen

class PostsListScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Posts'),
        actions: [
          IconButton(
            icon: Icon(Icons.refresh),
            onPressed: () {
              QueryClient().invalidateQuery('posts');
            },
          ),
        ],
      ),
      body: QueryBuilder<List<Post>>(
        queryKey: 'posts',
        queryFn: () => CrudApiService.getPosts(),
        builder: (context, state) {
          return state.when(
            loading: () => Center(child: CircularProgressIndicator()),
            error: (error, stack) => Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Text('Error: $error'),
                  ElevatedButton(
                    onPressed: () {
                      QueryClient().invalidateQuery('posts');
                    },
                    child: Text('Retry'),
                  ),
                ],
              ),
            ),
            data: (posts) => ListView.builder(
              itemCount: posts.length,
              itemBuilder: (context, index) {
                final post = posts[index];
                return PostTile(post: post);
              },
            ),
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => CreatePostScreen(),
            ),
          );
        },
        child: Icon(Icons.add),
      ),
    );
  }
}

class PostTile extends StatelessWidget {
  final Post post;

  const PostTile({required this.post});

  @override
  Widget build(BuildContext context) {
    return Card(
      child: ListTile(
        title: Text(post.title),
        subtitle: Text(post.content),
        trailing: PopupMenuButton(
          itemBuilder: (context) => [
            PopupMenuItem(
              value: 'edit',
              child: Row(
                children: [
                  Icon(Icons.edit),
                  SizedBox(width: 8),
                  Text('Edit'),
                ],
              ),
            ),
            PopupMenuItem(
              value: 'delete',
              child: Row(
                children: [
                  Icon(Icons.delete, color: Colors.red),
                  SizedBox(width: 8),
                  Text('Delete', style: TextStyle(color: Colors.red)),
                ],
              ),
            ),
          ],
          onSelected: (value) {
            switch (value) {
              case 'edit':
                Navigator.push(
                  context,
                  MaterialPageRoute(
                    builder: (context) => EditPostScreen(post: post),
                  ),
                );
                break;
              case 'delete':
                _showDeleteDialog(context);
                break;
            }
          },
        ),
        onTap: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => PostDetailScreen(postId: post.id),
            ),
          );
        },
      ),
    );
  }

  void _showDeleteDialog(BuildContext context) {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text('Delete Post'),
        content: Text('Are you sure you want to delete "${post.title}"?'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: Text('Cancel'),
          ),
          TextButton(
            onPressed: () {
              Navigator.pop(context);
              _deletePost(context);
            },
            child: Text('Delete', style: TextStyle(color: Colors.red)),
          ),
        ],
      ),
    );
  }

  void _deletePost(BuildContext context) {
    MutationBuilder<void, String>(
      mutationFn: (id) => CrudApiService.deletePost(id),
      options: MutationOptions(
        onSuccess: (_, id) {
          QueryClient().invalidateQuery('posts');
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('Post deleted successfully')),
          );
        },
        onError: (error) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('Failed to delete post: $error')),
          );
        },
      ),
      builder: (context, state) {
        return state.mutate(post.id);
      },
    );
  }
}

Optimistic Updates

Optimistic CRUD Operations

class OptimisticUserTile extends StatelessWidget {
  final User user;

  const OptimisticUserTile({required this.user});

  @override
  Widget build(BuildContext context) {
    return MutationBuilder<User, Map<String, String>>(
      mutationFn: (data) => CrudApiService.updateUser(user.id, data),
      options: MutationOptions(
        onMutate: (data) {
          // Optimistically update cache
          final users = QueryClient().getQueryData<List<User>>('users');
          if (users != null) {
            final optimisticUser = user.copyWith(
              name: data['name'] ?? user.name,
              email: data['email'] ?? user.email,
              updatedAt: DateTime.now(),
            );

            final optimisticUsers = users.map((u) =>
              u.id == user.id ? optimisticUser : u
            ).toList();

            QueryClient().setQueryData('users', optimisticUsers);
          }
        },
        onSuccess: (updatedUser) {
          // Invalidate to get fresh data
          QueryClient().invalidateQuery('users');
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('User updated successfully')),
          );
        },
        onError: (error) {
          // Rollback on error
          QueryClient().invalidateQuery('users');
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('Failed to update user: $error')),
          );
        },
      ),
      builder: (context, state) {
        return Card(
          child: ListTile(
            title: Text(user.name),
            subtitle: Text(user.email),
            trailing: state.isLoading
                ? CircularProgressIndicator()
                : IconButton(
                    icon: Icon(Icons.edit),
                    onPressed: () {
                      _showEditDialog(context, state);
                    },
                  ),
          ),
        );
      },
    );
  }

  void _showEditDialog(BuildContext context, MutationState<User> state) {
    final nameController = TextEditingController(text: user.name);
    final emailController = TextEditingController(text: user.email);

    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text('Edit User'),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            TextField(
              controller: nameController,
              decoration: InputDecoration(labelText: 'Name'),
            ),
            SizedBox(height: 16),
            TextField(
              controller: emailController,
              decoration: InputDecoration(labelText: 'Email'),
            ),
          ],
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: Text('Cancel'),
          ),
          TextButton(
            onPressed: () {
              Navigator.pop(context);
              state.mutate({
                'name': nameController.text,
                'email': emailController.text,
              });
            },
            child: Text('Save'),
          ),
        ],
      ),
    );
  }
}

Batch Operations

Batch CRUD Operations

class BatchOperationsScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Batch Operations')),
      body: Column(
        children: [
          ElevatedButton(
            onPressed: () => _batchCreateUsers(),
            child: Text('Batch Create Users'),
          ),
          ElevatedButton(
            onPressed: () => _batchUpdateUsers(),
            child: Text('Batch Update Users'),
          ),
          ElevatedButton(
            onPressed: () => _batchDeleteUsers(),
            child: Text('Batch Delete Users'),
          ),
        ],
      ),
    );
  }

  Future<void> _batchCreateUsers() async {
    final users = [
      {'name': 'User 1', 'email': 'user1@example.com'},
      {'name': 'User 2', 'email': 'user2@example.com'},
      {'name': 'User 3', 'email': 'user3@example.com'},
    ];

    try {
      await Future.wait(
        users.map((userData) => CrudApiService.createUser(userData)),
      );

      QueryClient().invalidateQuery('users');
      print('Batch create completed');
    } catch (error) {
      print('Batch create failed: $error');
    }
  }

  Future<void> _batchUpdateUsers() async {
    final updates = [
      {'id': '1', 'name': 'Updated User 1'},
      {'id': '2', 'name': 'Updated User 2'},
      {'id': '3', 'name': 'Updated User 3'},
    ];

    try {
      await Future.wait(
        updates.map((update) => CrudApiService.updateUser(
          update['id']!,
          {'name': update['name']!},
        )),
      );

      QueryClient().invalidateQuery('users');
      print('Batch update completed');
    } catch (error) {
      print('Batch update failed: $error');
    }
  }

  Future<void> _batchDeleteUsers() async {
    final userIds = ['1', '2', '3'];

    try {
      await Future.wait(
        userIds.map((id) => CrudApiService.deleteUser(id)),
      );

      QueryClient().invalidateQuery('users');
      print('Batch delete completed');
    } catch (error) {
      print('Batch delete failed: $error');
    }
  }
}

Best Practices

1. Use proper validation - Validate input data before sending requests
2. Implement optimistic updates - Provide instant feedback for better UX
3. Handle errors gracefully - Show meaningful error messages
4. Invalidate related queries - Keep data consistent across the app
5. Use batch operations - Improve performance for bulk operations
6. Implement proper loading states - Show progress indicators
7. Cache management - Use appropriate cache policies for different data types

Next Steps

• Real-time Data - Learn about real-time patterns
• File Operations - Learn about file handling
• Database Queries - Learn about database patterns