Examples

Complete working examples using the Fasq Hooks adapter.

Basic User Management

A complete example showing user listing, creation, and deletion:


import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';
import 'package:fasq_hooks/fasq_hooks.dart';
 
class User {
  final String id;
  final String name;
  final String email;
  
  User({required this.id, required this.name, required this.email});
  
  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      id: json['id'],
      name: json['name'],
      email: json['email'],
    );
  }
}
 
class ApiService {
  Future<List<User>> fetchUsers() async {
    await Future.delayed(Duration(seconds: 1)); // Simulate network
    return [
      User(id: '1', name: 'Alice', email: 'alice@example.com'),
      User(id: '2', name: 'Bob', email: 'bob@example.com'),
    ];
  }
  
  Future<User> createUser(Map<String, String> data) async {
    await Future.delayed(Duration(seconds: 1));
    return User(
      id: DateTime.now().millisecondsSinceEpoch.toString(),
      name: data['name']!,
      email: data['email']!,
    );
  }
  
  Future<void> deleteUser(String id) async {
    await Future.delayed(Duration(seconds: 1));
  }
}
 
class UserManagementScreen extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final usersState = useQuery<List<User>>('users', () => ApiService().fetchUsers());
    final createUser = useMutation<User, Map<String, String>>(
      (data) => ApiService().createUser(data),
      options: MutationOptions(
        onSuccess: (user) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('User ${user.name} created!')),
          );
          useQueryClient().invalidateQuery('users');
        },
      ),
    );
    final deleteUser = useMutation<void, String>(
      (id) => ApiService().deleteUser(id),
      options: MutationOptions(
        onSuccess: (_, id) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('User deleted')),
          );
          useQueryClient().invalidateQuery('users');
        },
      ),
    );
    
    return Scaffold(
      appBar: AppBar(title: Text('User Management')),
      body: Column(
        children: [
          Expanded(
            child: usersState.when(
              idle: () => Center(child: Text('Ready to load users')),
              loading: () => Center(child: CircularProgressIndicator()),
              error: (error, stack) => Center(
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Text('Error: $error'),
                    ElevatedButton(
                      onPressed: () => useQueryClient().getQueryByKey<List<User>>('users')?.fetch(),
                      child: Text('Retry'),
                    ),
                  ],
                ),
              ),
              data: (users) => ListView.builder(
                itemCount: users.length,
                itemBuilder: (context, index) {
                  final user = users[index];
                  return ListTile(
                    title: Text(user.name),
                    subtitle: Text(user.email),
                    trailing: IconButton(
                      icon: Icon(Icons.delete),
                      onPressed: deleteUser.isLoading ? null : () => deleteUser.mutate(user.id),
                    ),
                  );
                },
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsets.all(16.0),
            child: ElevatedButton(
              onPressed: createUser.isLoading ? null : () => _showCreateUserDialog(context, createUser),
              child: createUser.isLoading
                  ? CircularProgressIndicator()
                  : Text('Add User'),
            ),
          ),
        ],
      ),
    );
  }
  
  void _showCreateUserDialog(BuildContext context, MutationState<User, Map<String, String>> createUser) {
    showDialog(
      context: context,
      builder: (context) => CreateUserDialog(createUser: createUser),
    );
  }
}
 
class CreateUserDialog extends HookWidget {
  final MutationState<User, Map<String, String>> createUser;
  
  const CreateUserDialog({required this.createUser});
  
  @override
  Widget build(BuildContext context) {
    final nameController = useTextEditingController();
    final emailController = useTextEditingController();
    
    return AlertDialog(
      title: Text('Create User'),
      content: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          TextField(
            controller: nameController,
            decoration: InputDecoration(labelText: 'Name'),
          ),
          TextField(
            controller: emailController,
            decoration: InputDecoration(labelText: 'Email'),
          ),
        ],
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: Text('Cancel'),
        ),
        ElevatedButton(
          onPressed: createUser.isLoading ? null : () {
            createUser.mutate({
              'name': nameController.text,
              'email': emailController.text,
            });
            Navigator.pop(context);
          },
          child: createUser.isLoading
              ? CircularProgressIndicator()
              : Text('Create'),
        ),
      ],
    );
  }
}

Pagination Example

Implementing pagination with hooks:


class PaginatedUsersScreen extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final page = useState(1);
    final pageSize = 10;
    
    final usersState = useQuery<List<User>>(
      'users:page:${page.value}',
      () => ApiService().fetchUsersPage(page.value, pageSize),
      options: QueryOptions(
        staleTime: Duration(minutes: 5), // Keep pages fresh for 5 minutes
      ),
    );
    
    return Scaffold(
      appBar: AppBar(title: Text('Paginated Users')),
      body: Column(
        children: [
          Expanded(
            child: usersState.when(
              loading: () => Center(child: CircularProgressIndicator()),
              error: (error, stack) => Center(child: Text('Error: $error')),
              data: (users) => ListView.builder(
                itemCount: users.length,
                itemBuilder: (context, index) {
                  final user = users[index];
                  return ListTile(
                    title: Text(user.name),
                    subtitle: Text(user.email),
                  );
                },
              ),
            ),
          ),
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: [
              ElevatedButton(
                onPressed: page.value > 1 ? () => page.value-- : null,
                child: Text('Previous'),
              ),
              Text('Page ${page.value}'),
              ElevatedButton(
                onPressed: () => page.value++,
                child: Text('Next'),
              ),
            ],
          ),
        ],
      ),
    );
  }
}

Real-time Updates

Simulating real-time updates with polling:


class RealTimeUsersScreen extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final usersState = useQuery<List<User>>(
      'users:realtime',
      () => ApiService().fetchUsers(),
      options: QueryOptions(
        refetchInterval: Duration(seconds: 30), // Poll every 30 seconds
        refetchOnWindowFocus: true, // Refetch when app regains focus
      ),
    );
    
    return Scaffold(
      appBar: AppBar(
        title: Text('Real-time Users'),
        actions: [
          IconButton(
            icon: Icon(Icons.refresh),
            onPressed: () => useQueryClient().getQueryByKey<List<User>>('users:realtime')?.fetch(),
          ),
        ],
      ),
      body: usersState.when(
        loading: () => Center(child: CircularProgressIndicator()),
        error: (error, stack) => Center(child: Text('Error: $error')),
        data: (users) => Column(
          children: [
            if (usersState.isFetching && !usersState.isLoading)
              LinearProgressIndicator(),
            Expanded(
              child: ListView.builder(
                itemCount: users.length,
                itemBuilder: (context, index) {
                  final user = users[index];
                  return ListTile(
                    title: Text(user.name),
                    subtitle: Text(user.email),
                    trailing: Text('Updated: ${DateTime.now().toString().substring(11, 19)}'),
                  );
                },
              ),
            ),
          ],
        ),
      ),
    );
  }
}

Optimistic Updates

Implementing optimistic updates for instant feedback:


class OptimisticUserScreen extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final usersState = useQuery<List<User>>('users', () => ApiService().fetchUsers());
    final updateUser = useMutation<User, User>(
      (user) => ApiService().updateUser(user),
      options: MutationOptions(
        onMutate: (updatedUser) {
          // Optimistically update cache
          final currentUsers = useQueryClient().getQueryData<List<User>>('users');
          final optimisticUsers = currentUsers?.map((u) => 
            u.id == updatedUser.id ? updatedUser : u
          ).toList();
          
          useQueryClient().setQueryData('users', optimisticUsers);
        },
        onSuccess: (user) {
          // Invalidate to get fresh data
          useQueryClient().invalidateQuery('users');
        },
        onError: (error) {
          // Rollback on error
          useQueryClient().invalidateQuery('users');
        },
      ),
    );
    
    return Scaffold(
      appBar: AppBar(title: Text('Optimistic Updates')),
      body: usersState.when(
        loading: () => Center(child: CircularProgressIndicator()),
        error: (error, stack) => Center(child: Text('Error: $error')),
        data: (users) => ListView.builder(
          itemCount: users.length,
          itemBuilder: (context, index) {
            final user = users[index];
            return ListTile(
              title: Text(user.name),
              subtitle: Text(user.email),
              trailing: Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  IconButton(
                    icon: Icon(Icons.edit),
                    onPressed: updateUser.isLoading ? null : () {
                      final updatedUser = User(
                        id: user.id,
                        name: '${user.name} (Updated)',
                        email: user.email,
                      );
                      updateUser.mutate(updatedUser);
                    },
                  ),
                ],
              ),
            );
          },
        ),
      ),
    );
  }
}

Custom Hook Example

Creating a reusable custom hook:


// Custom hook for user management
QueryState<List<User>> useUsers() {
  return useQuery<List<User>>(
    'users',
    () => ApiService().fetchUsers(),
    options: QueryOptions(
      staleTime: Duration(minutes: 5),
    ),
  );
}
 
MutationState<User, Map<String, String>> useCreateUser() {
  return useMutation<User, Map<String, String>>(
    (data) => ApiService().createUser(data),
    options: MutationOptions(
      onSuccess: (user) {
        useQueryClient().invalidateQuery('users');
      },
    ),
  );
}
 
MutationState<void, String> useDeleteUser() {
  return useMutation<void, String>(
    (id) => ApiService().deleteUser(id),
    options: MutationOptions(
      onSuccess: (_, id) {
        useQueryClient().invalidateQuery('users');
      },
    ),
  );
}
 
// Using the custom hooks
class UserScreenWithCustomHooks extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final usersState = useUsers();
    final createUser = useCreateUser();
    final deleteUser = useDeleteUser();
    
    return Scaffold(
      appBar: AppBar(title: Text('Custom Hooks Example')),
      body: usersState.when(
        loading: () => Center(child: CircularProgressIndicator()),
        error: (error, stack) => Center(child: Text('Error: $error')),
        data: (users) => ListView.builder(
          itemCount: users.length,
          itemBuilder: (context, index) {
            final user = users[index];
            return ListTile(
              title: Text(user.name),
              subtitle: Text(user.email),
              trailing: IconButton(
                icon: Icon(Icons.delete),
                onPressed: deleteUser.isLoading ? null : () => deleteUser.mutate(user.id),
              ),
            );
          },
        ),
      ),
    );
  }
}

Error Boundary Example

Implementing error boundaries with hooks:


class ErrorBoundary extends HookWidget {
  final Widget child;
  final Widget Function(Object error)? errorBuilder;
  
  const ErrorBoundary({
    required this.child,
    this.errorBuilder,
  });
  
  @override
  Widget build(BuildContext context) {
    final error = useState<Object?>(null);
    
    return Builder(
      builder: (context) {
        if (error.value != null) {
          return errorBuilder?.call(error.value!) ?? 
            Center(child: Text('Error: ${error.value}'));
        }
        
        return child;
      },
    );
  }
}
 
class UsersScreenWithErrorBoundary extends HookWidget {
  @override
  Widget build(BuildContext context) {
    return ErrorBoundary(
      errorBuilder: (error) => Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(Icons.error, size: 64, color: Colors.red),
            SizedBox(height: 16),
            Text('Something went wrong'),
            SizedBox(height: 8),
            Text('$error'),
            SizedBox(height: 16),
            ElevatedButton(
              onPressed: () => Navigator.pop(context),
              child: Text('Go Back'),
            ),
          ],
        ),
      ),
      child: UserManagementScreen(),
    );
  }
}

Performance Optimization

Optimizing performance with proper cache configuration:


class OptimizedUsersScreen extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final usersState = useQuery<List<User>>(
      'users',
      () => ApiService().fetchUsers(),
      options: QueryOptions(
        staleTime: Duration(minutes: 10), // Keep fresh for 10 minutes
        cacheTime: Duration(minutes: 30), // Keep in cache for 30 minutes
        refetchOnWindowFocus: false, // Don't refetch on focus
        refetchOnMount: false, // Don't refetch on mount if data exists
      ),
    );
    
    return Scaffold(
      appBar: AppBar(title: Text('Optimized Users')),
      body: usersState.when(
        loading: () => Center(child: CircularProgressIndicator()),
        error: (error, stack) => Center(child: Text('Error: $error')),
        data: (users) => ListView.builder(
          itemCount: users.length,
          itemBuilder: (context, index) {
            final user = users[index];
            return ListTile(
              title: Text(user.name),
              subtitle: Text(user.email),
            );
          },
        ),
      ),
    );
  }
}

Next Steps

useQuery - Learn about the useQuery hook
useMutation - Learn about the useMutation hook
useQueryClient - Learn about cache management
Custom Hooks - Creating reusable logic