React Query Retry Guide

React Query is a powerful tool for fetching, caching, and updating data in React applications. One of its standout features is the ability to automatically retry failed queries, enhancing the robustness and reliability of data fetching. This guide dives into the retry mechanism of React Query, providing insights and best practices for effectively using retries in your projects.

What is the retry mechanism in React Query?

React Query's retry mechanism is designed to handle transient errors in data fetching, such as network issues or server downtime. By default, React Query retries a failed query three times, with exponential backoff, before marking it as an error.

How to configure retry attempts

To customize the number of retry attempts, you can modify the retry option in the query's configuration. Here's how to set a specific number of retries:

useQuery('todos', fetchTodos, {
  retry: 5 // Retry up to 5 times
})

If you want to disable retries entirely, set the retry option to false:

useQuery('todos', fetchTodos, {
  retry: false // No retries
})

How to implement a custom retry delay

React Query allows you to define a custom function for retry delays. This function receives the retry attempt index and the error and returns the delay in milliseconds.

useQuery('todos', fetchTodos, {
  retryDelay: (attemptIndex, error) => {
    // Custom logic for delay
    return Math.min(1000 * 2 ** attemptIndex, 30000);
  }
})

Retry only for specific errors

Sometimes, you may want to retry queries only for certain types of errors. You can achieve this by passing a function to the retry option:

useQuery('todos', fetchTodos, {
  retry: (failureCount, error) => {
    // Retry only for specific error types
    return error.status === 404 ? false : true;
  }
})

How to use useMutation for retry

React Query's retry mechanism also applies to mutations. This can be particularly useful for operations that might temporarily fail, like submitting a form to a server.

const mutation = useMutation(submitForm, {
  retry: 3 // Retry the mutation up to 3 times
})

Integrate retry with error handling

Effective use of retries involves robust error handling. React Query provides the onError callback for handling errors after all retries have been exhausted.

useQuery('todos', fetchTodos, {
  retry: 3,
  onError: (error) => {
    // Handle the error after retries
    console.error('Failed to fetch todos:', error);
  }
})

Conclusion

Incorporating React Query's retry mechanism can significantly improve the resilience of your application. By understanding and effectively configuring retries, you can ensure that your application handles data fetching more reliably, providing a smoother user experience. For more advanced features and configurations, refer to the React Query documentation.