How to Handle errors within custom SWR hook

When handling errors in custom SWR (Stale-While-Revalidate) hooks, the primary goal is to effectively capture, handle, and provide users with appropriate feedback on errors. This enhances the application's robustness and user experience. Below are some steps and examples for handling such errors:

1. Error Capture

First, ensure that all potential errors during data fetching are captured. When using the SWR library, leverage the error return value to obtain error states.

javascript
import useSWR from 'swr';

function useCustomHook(url) {
  const { data, error, isValidating } = useSWR(url);

  return {
    data,
    isLoading: !error && !data,
    isError: error
  };
}

2. Error Handling

After capturing errors, implement a strategy to handle them. Error handling may include retry mechanisms, error logging, or error notifications.

javascript
import useSWR from 'swr';

function useCustomHook(url) {
  const { data, error, isValidating, mutate } = useSWR(url, {
    onErrorRetry: (error, key, config, revalidate, { retryCount }) => {
      // Limit retry attempts
      if (retryCount >= 3) return;
      // Retry after 2 seconds
      setTimeout(() => revalidate({ retryCount }), 2000);
    }
  });

  return {
    data,
    isLoading: !error && !data,
    isError: error
  };
}

3. User Feedback

Error information should be fed back to users to clarify the current state and potential solutions. This can be achieved through UI prompts or error message displays.

javascript
function Component() {
  const { data, isLoading, isError } = useCustomHook('api/data');

  if (isLoading) return <div>Loading...</div>;
  if (isError) return <div>Error occurred! Please try again later.</div>;

  return <div>{data}</div>;
}

4. Global Error Management

For more complex applications, consider implementing a global error management mechanism, such as using Error Boundaries or state management libraries (e.g., Redux) to centralize error handling.

5. Logging

Logging errors is crucial for tracing error sources and diagnosing issues. Consider sending error information to a backend server or using third-party logging services.

javascript
function logError(error) {
  console.error(error);
  // Add code to send to server here
}

function useCustomHook(url) {
  const { data, error, isValidating } = useSWR(url, {
    onError: logError
  });

  return {
    data,
    isLoading: !error && !data,
    isError: error
  };
}

Conclusion

By following these steps, we can systematically handle and provide feedback for errors occurring in custom SWR hooks, not only enhancing user experience but also improving application stability and maintainability.