Using React Query with Next.js

What You’ll Learn 📚

• Core concepts of React Query and how it integrates with Next.js
• Key terminology and definitions
• Step-by-step examples from simple to complex
• Common questions and troubleshooting tips

Introduction to React Query and Next.js

Before we jump into the code, let’s get a quick overview of what React Query and Next.js are:

• React Query: A powerful library for fetching, caching, and updating asynchronous data in React applications. It simplifies data fetching and state management, making your code cleaner and more efficient.
• Next.js: A popular React framework that enables server-side rendering and static site generation, among other features. It helps you build fast and SEO-friendly web applications.

Why Use React Query with Next.js?

Combining React Query with Next.js allows you to efficiently manage server-side data fetching and caching, providing a seamless user experience. With React Query, you can handle loading states, error handling, and background data synchronization effortlessly.

Key Terminology

• Query: A request for data that React Query manages. It can be a REST API call, GraphQL query, etc.
• Mutation: An operation that modifies data on the server, like adding or updating a record.
• Cache: A storage layer that React Query uses to store and retrieve data efficiently.

Getting Started: The Simplest Example

Let’s start with a simple example to fetch data using React Query in a Next.js application.

Setup Instructions

1. Create a new Next.js project:

   npx create-next-app react-query-example

2. Navigate to the project directory:

   cd react-query-example

3. Install React Query:

   npm install react-query

Basic Example: Fetching Data

import React from 'react'; import { useQuery } from 'react-query'; const fetchPosts = async () => { const res = await fetch('https://jsonplaceholder.typicode.com/posts'); return res.json(); }; export default function Posts() { const { data, error, isLoading } = useQuery('posts', fetchPosts); if (isLoading) return 
Loading...
; if (error) return 
Error: {error.message}
; return ( 
 
Posts
 
 {data.map(post => ( 
{post.title}
 ))} 
 
 ); }

Expected Output

Progressively Complex Examples

Example 1: Using Mutations

Let’s add a feature to create a new post using a mutation.

import React, { useState } from 'react'; import { useMutation, useQueryClient } from 'react-query'; const createPost = async (newPost) => { const res = await fetch('https://jsonplaceholder.typicode.com/posts', { method: 'POST', body: JSON.stringify(newPost), headers: { 'Content-Type': 'application/json' } }); return res.json(); }; export default function AddPost() { const queryClient = useQueryClient(); const [title, setTitle] = useState(''); const mutation = useMutation(createPost, { onSuccess: () => { queryClient.invalidateQueries('posts'); } }); const handleSubmit = (e) => { e.preventDefault(); mutation.mutate({ title }); }; return ( 
  setTitle(e.target.value)} placeholder='Post title' /> Add Post 
 ); }

Example 2: Paginated Queries

Implementing pagination with React Query is straightforward. Let’s see how:

import React, { useState } from 'react'; import { useQuery } from 'react-query'; const fetchPosts = async (page) => { const res = await fetch(`https://jsonplaceholder.typicode.com/posts?_page=${page}`); return res.json(); }; export default function PaginatedPosts() { const [page, setPage] = useState(1); const { data, isLoading, isError } = useQuery(['posts', page], () => fetchPosts(page)); if (isLoading) return 
Loading...
; if (isError) return 
Error loading posts
; return ( 
 
Posts
 
 {data.map(post => ( 
{post.title}
 ))} 
  setPage((prev) => prev - 1)} disabled={page === 1}>Previous  setPage((prev) => prev + 1)}>Next 
 ); }

Common Questions and Answers

1. What is React Query?

   React Query is a library for managing server state in React applications, simplifying data fetching and caching.

2. How does React Query improve performance?

   By caching data and minimizing unnecessary network requests, React Query enhances performance and reduces load times.

3. Can I use React Query with other frameworks?

   Yes, while it’s designed for React, you can adapt its concepts to other frameworks with similar state management needs.

Troubleshooting Common Issues

If you encounter issues with data not updating, ensure you’re invalidating queries correctly after mutations.

Remember to handle loading and error states to improve user experience and provide feedback.

Practice Exercises

1. Create a new feature to delete a post using React Query mutations.
2. Implement infinite scrolling for the posts list.

Don’t worry if this seems complex at first. With practice, you’ll become more comfortable with these concepts. Keep experimenting and happy coding! 💪