Mastering Error Handling and Retry Strategies with React Query

Introduction:

Error handling is a critical aspect of building robust and user-friendly web applications. In this blog post, we'll explore how to effectively handle errors and implement retry strategies using React Query.

We'll cover practical use cases, including handling and displaying errors withuseQueryanduseMutation, implementing retry policies with exponential backoff, and managing errors globally with error boundaries.

By the end, you'll have a solid understanding of these concepts and be equipped to handle errors gracefully in your React applications.

Example 1: Handling Query Errors

import { useQuery } from 'react-query';

const fetchUserData = async (userId) => {
  const response = await fetch(`/api/users/${userId}`);

  if (!response.ok) {
    throw new Error('Failed to fetch user data');
  }

  return response.json();
};

const UserProfile = ({ userId }) => {
  const { data, error } = useQuery(['userData', userId], () => fetchUserData(userId));

  if (error) {
    return <div>Error: {error.message}</div>;
  }

  // Render the user profile data
};

In this example, we fetch user data using the useQuery hook. If the API call fails (indicated by a non-ok response), we throw an error.

The error variable from the useQuery result allows us to handle and display the error message to the user, providing feedback in case of any data fetching issues.

Example 2: Handling Mutation Errors

import { useMutation } from 'react-query';

const updateUserProfile = async (userId, data) => {
  const response = await fetch(`/api/users/${userId}`, {
    method: 'PUT',
    body: JSON.stringify(data),
    headers: {
      'Content-Type': 'application/json',
    },
  });

  if (!response.ok) {
    throw new Error('Failed to update user profile');
  }

  return response.json();
};

const ProfileForm = ({ userId }) => {
  const { mutate, error } = useMutation((data) => updateUserProfile(userId, data));

  const handleSubmit = (formData) => {
    mutate(formData);
  };

  if (error) {
    return <div>Error: {error.message}</div>;
  }

  // Render the profile form
};

In this example, we use the useMutation hook to handle updating the user profile. If the API call fails, indicated by a non-ok response, we throw an error.

Similar to the previous example, we can handle and display the error message to the user using the error variable from the useMutation result.

Retry Strategies and Global Error Handling:

Example 3: Retry Policies with Exponential Backoff

import { useQuery } from 'react-query';

const fetchUserData = async (userId) => {
  const response = await fetch(`/api/users/${userId}`);

  if (!response.ok) {
    throw new Error('Failed to fetch user data');
  }

  return response.json();
};

const UserProfile = ({ userId }) => {
  const { data, error } = useQuery(['userData', userId], () => fetchUserData(userId), {
    retry: 3,
    retryDelay: (attempt) => Math.pow(2, attempt) * 1000,
  });

  if (error) {
    return <div>Error: {error.message}</div>;
  }

  // Render the user profile data
};

In this example, we introduce retry policies with exponential backoff. By setting the retry option to 3 and the retryDelay option to a function

that exponentially increases the delay between retries, we attempt to refetch the user data up to 3 times with increasing delays between each attempt.

This strategy improves the chances of successful data fetching in case of temporary failures.

Example 4: Global Error Handling with Error Boundaries

import { QueryClient, QueryClientProvider, ErrorBoundary } from 'react-query';

const queryClient = new QueryClient();

const App = () => {
  return (
    <QueryClientProvider client={queryClient}>
      <ErrorBoundary fallback={<div>An error occurred. Please try again.</div>}>
        {/* Your app components */}
      </ErrorBoundary>
    </QueryClientProvider>
  );
};

In this example, we showcase global error handling using React Query's ErrorBoundary component.

By wrapping our app components with an ErrorBoundary, we can provide a fallback UI in case of unhandled errors within the React Query context. This ensures a smooth user experience even when unexpected errors occur.

Summary:

• React Query provides mechanisms to handle and display errors using the useQuery and useMutation hooks.

• Retry strategies with exponential backoff improve data fetching success rates in case of temporary failures.

• Global error handling using React Query's ErrorBoundary ensures a consistent fallback UI for unhandled errors.

• These concepts empower developers to handle errors gracefully, provide meaningful error feedback to users, and improve data fetching reliability in React applications.

By implementing these error handling and retry strategies, you can enhance the robustness and user experience of your React applications. Experiment with these examples, explore React Query's documentation for additional customization options, and master the art of handling errors in your projects. Happy coding!