ReactQuery make refetch with old data

React Query is a powerful library for handling server state retrieval, caching, and updates within React applications. When dealing with re-fetching using stale data, React Query provides several effective methods to ensure the application's data remains up-to-date while delivering a smooth user experience. I will explain this in detail from the following aspects:

1. Background Understanding

React Query defaults to the Optimistic Updates strategy, which temporarily displays stale data as the current content before issuing new data requests. This approach minimizes UI jank and loading states, enhancing user experience.

2. Scenarios for Using Stale Data

• Maintaining User Interface Continuity: Using stale data during data refresh or re-fetching ensures seamless user interface continuity, avoiding flickering caused by data updates.
• Performance Optimization: Displaying stale data while waiting for new data to load reduces white-screen time, improving perceived performance.

3. Implementation

In React Query, we can control data freshness and cache duration by configuring the staleTime and cacheTime parameters. For example:

javascript
useQuery('todos', fetchTodos, {
  staleTime: 300000,  // Data is considered fresh for 5 minutes
  cacheTime: 900000   // Cache is maintained for 15 minutes
});

Here, even if the data source updates, users won't perceive changes within 5 minutes, leveraging stale data to optimize the experience.

4. Re-fetching Strategies

React Query offers multiple re-fetching strategies:

• On Window Focus: Trigger re-fetching when the window regains focus.
• On Network Reconnect: Trigger re-fetching when the network reconnects.
• Polling: Periodically polling data.

These strategies can be combined with stale data usage to maintain data freshness without compromising user experience.

5. Example Explanation

Consider a news application where a user is reading an article. If data updates immediately affect the current page, it may cause discomfort. Using React Query's stale data display alongside minor background updates (e.g., checking for new data every 10 minutes) significantly enhances user experience.

Summary

React Query's stale data re-fetching mechanism ensures data freshness while effectively balancing real-time updates and user experience. By properly configuring staleTime, cacheTime, and suitable re-fetching strategies, React applications become more efficient and user-friendly.