Vue Query (TanStack Query) for State Management

What is Vue Query?

Vue Query (now part of TanStack Query) is a powerful data-fetching and state management library specifically designed for managing server state in Vue.js applications. It provides intelligent caching, background updates, and synchronization features that eliminate the boilerplate code typically associated with data fetching and state management.

Key Features

• Intelligent Caching: Automatic caching with configurable cache invalidation strategies
• Background Refetching: Keep data fresh with background updates
• Optimistic Updates: Update UI immediately while syncing with server
• Request Deduplication: Prevent duplicate requests for the same data
• Pagination Support: Built-in support for paginated data
• Infinite Queries: Handle infinite scrolling scenarios
• DevTools: Comprehensive debugging tools for query inspection
• TypeScript Support: Full type safety with excellent inference

When to Use Vue Query

Ideal Use Cases

1. Server State Management: When your state heavily relies on server data
2. Real-time Data: Applications requiring frequent data synchronization
3. Complex Data Fetching: Multiple dependent queries, pagination, or infinite loading
4. Caching Requirements: When you need sophisticated caching strategies
5. Background Sync: Applications that need to keep data fresh automatically
6. Optimistic UI Updates: When you want immediate UI feedback for user actions
7. API-Heavy Applications: REST APIs, GraphQL, or any data fetching scenario

Best Practices

1. Query Key Structure

Query keys are crucial for caching and invalidation. They should be hierarchical and descriptive to enable precise cache management.

useQuery({
  queryKey: ["users"], // Cache key for all users
  queryFn: () => fetchUsers(),
});

useQuery({
  queryKey: ["users", 123], // Cache key for user with ID 123
  queryFn: () => fetchUser(123),
});

useQuery({
  queryKey: ["users", 123, "posts"], // Posts for user 123
  queryFn: () => fetchUserPosts(123),
});

2. Cache Management

// Invalidate related queries after mutations
onSuccess: () => {
  queryClient.invalidateQueries({ queryKey: ["users"] });
  queryClient.invalidateQueries({ queryKey: ["posts", "user", userId] });
};

// Remove specific cache entries
queryClient.removeQueries({ queryKey: ["users", deletedUserId] });

3. Loading States

export function useUserData(userId) {
  const query = useQuery({
    queryKey: ["user", userId],
    queryFn: () => fetchUser(userId),
  });

  return {
    ...query,
    isEmpty: computed(() => !query.isLoading.value && !query.data.value),
    isError: query.isError,
    isSuccess: query.isSuccess,
  };
}

Vue Query vs Other Solutions

Feature	Vue Query	Composables	Pinia	Plain Fetch
Caching	✅ Advanced	❌ Manual	❌ Manual	❌ None
Background Sync	✅ Automatic	❌ Manual	❌ Manual	❌ None
Deduplication	✅ Built-in	❌ Manual	❌ Manual	❌ None
DevTools	✅ Comprehensive	❌ Basic	✅ Good	❌ None
Learning Curve	📈 Medium	📈 Low	📈 Medium	📈 Low
Bundle Size	📦 Medium	📦 Minimal	📦 Small	📦 None

References

Official Documentation

• TanStack Query Docs
• Quick Start
• API Reference

Core Concepts

• Queries
• Mutations
• Query Invalidation
• Caching

Advanced Topics

• Optimistic Updates
• Infinite Queries
• Dependent Queries
• DevTools