Error Handling and Retries in React Query: A Developer’s Guide

In the world of web development, handling errors gracefully is just as important as managing successful responses. React Query, a powerful data-fetching library, provides robust error handling and retry mechanisms that can significantly improve your application’s reliability. Let’s dive into how we can leverage these features effectively.

Understanding Error Handling Basics

When things go wrong in our API calls, React Query doesn’t just throw in the towel. Instead, it gives us powerful tools to catch, handle, and recover from errors. This means better user experience and fewer headaches for developers.

Error States in React Query

React Query provides several ways to handle errors in your queries. The most basic approach is using the error state that comes with every query:

const { data, error, isError } = useQuery('userData', fetchUserData);

if (isError) {
  return <div>Something went wrong: {error.message}</div>;
}

But there’s more to it than just displaying error messages. You can also handle errors at different levels:

1. Query-level error handling
2. Global error handling
3. Custom error handlers

Implementing Retry Logic

React Query ships with built-in retry capabilities that can help your application recover from temporary failures. By default, it will retry failed queries three times with exponential backoff.

const { data } = useQuery('userData', fetchUserData, {
  retry: 3,
  retryDelay: attemptIndex => Math.min(1000 * 2 ** attemptIndex, 30000),
});

Advanced Error Handling Patterns

One of the most powerful aspects of React Query is its ability to handle errors contextually. Here’s a more sophisticated approach:

const { data, error } = useQuery('userData', fetchUserData, {
  retry: (failureCount, error) => {
    if (error.status === 404) return false; // don't retry if resource not found
    return failureCount < 3;
  },
  onError: (error) => {
    logger.error('Failed to fetch user data:', error);
  },
});

Global Error Configuration

For consistent error handling across your application, you can configure default behaviors:

const queryClient = new QueryClient({
  defaultOptions: {
    queries: {
      retry: 2,
      retryDelay: attemptIndex => Math.min(1000 * 2 ** attemptIndex, 30000),
      onError: (error) => {
        // Global error handling
        notifyError(error);
      },
    },
  },
});

Best Practices for Error Handling

1. Always provide meaningful error messages to users
2. Implement different strategies for different types of errors
3. Log errors appropriately for debugging
4. Consider retry strategies carefully based on error types
5. Use error boundaries for catching render errors

Tips for Testing Error Scenarios

Remember to test your error handling logic thoroughly. Here’s what you should consider:

• Test different types of API failures
• Verify retry behavior works as expected
• Ensure error states are handled gracefully in the UI
• Test error recovery scenarios

Conclusion

Proper error handling and retry logic are crucial for building robust React applications. React Query provides the tools we need to handle these scenarios elegantly, improving both the developer experience and end-user satisfaction.