All about React Query

Getting Started with React Query: Simplify Server State Management
In modern React applications, managing server state effectively can be a complex task. While tools like Redux and Context API work well for client state, they often require additional boilerplate to manage server-side data. This is where React Query shines—it simplifies server state management and enhances data fetching, caching, and synchronization in your React app.

What is React Query?
React Query is a powerful library for fetching, caching, synchronizing, and updating server state in React applications. It eliminates the need for complex state management boilerplates and provides features out-of-the-box that save time and improve application performance.

Key Features
Data Fetching and Caching: Automatically caches server data and keeps it fresh.
Stale-While-Revalidate Mechanism: Ensures that your UI remains up-to-date with minimal API calls.
Out-of-the-Box Support for Background Updates: React Query handles re-fetching data in the background.
Error Handling: Provides robust error handling with minimal configuration.
Server State Synchronization: Automatically syncs your UI when server state changes.
DevTools: Debug your queries with an intuitive and easy-to-use DevTools interface.
*Why Use React Query?
*
React Query reduces boilerplate code and enhances developer productivity. It provides an intuitive API to handle common scenarios like:

Data fetching with retries.
Pagination and infinite scrolling.
Dependent queries.
Optimistic updates.
Installation
Getting started with React Query is straightforward:

 npm install @tanstack/react-query

You’ll also want to install the optional but highly recommended React Query Devtools:

`npm install @tanstack/react-query-devtools`

Basic Usage
Here’s how you can use React Query to fetch and display data:

Setup the QueryClient
Wrap your app with the QueryClientProvider:

import { QueryClient, QueryClientProvider } from '@tanstack/react-query';

const queryClient = new QueryClient();

function App() {
  return (
    <QueryClientProvider client={queryClient}>
      <MyComponent />
    </QueryClientProvider>
  );
}

*Fetching Data with useQuery
*
The useQuery hook is the heart of React Query. It lets you fetch data and automatically manages the request lifecycle:

import { useQuery } from '@tanstack/react-query';
import axios from 'axios';

const fetchData = async () => {
  const { data } = await axios.get('https://api.example.com/items');
  return data;
};

function MyComponent() {
  const { data, isLoading, error } = useQuery(['items'], fetchData);

  if (isLoading) return <div>Loading...</div>;
  if (error) return <div>Error loading data</div>;

  return (
    <ul>
      {data.map(item => (
        <li key={item.id}>{item.name}</li>
      ))}
    </ul>
  );
}

*Advanced Features
*
*1. Mutations
*
React Query also supports data updates with useMutation. This is particularly useful for handling form submissions or other operations that modify data.

import { useMutation, useQueryClient } from '@tanstack/react-query';
import axios from 'axios';

const addItem = async (newItem) => {
  const { data } = await axios.post('https://api.example.com/items', newItem);
  return data;
};

function AddItemForm() {
  const queryClient = useQueryClient();

  const mutation = useMutation(addItem, {
    onSuccess: () => {
      queryClient.invalidateQueries(['items']); // Refetch the data
    },
  });

  const handleSubmit = () => {
    mutation.mutate({ name: 'New Item' });
  };

  return <button onClick={handleSubmit}>Add Item</button>;
}

2. Query Invalidation
When your server data changes, React Query makes it easy to refresh your UI by invalidating specific queries:

queryClient.invalidateQueries(['items']);

3. Infinite Queries
Support for infinite scrolling is baked right in:

import { useInfiniteQuery } from '@tanstack/react-query';

const fetchItems = async ({ pageParam = 1 }) => {
  const { data } = await axios.get(`https://api.example.com/items?page=${pageParam}`);
  return data;
};

function InfiniteScroll() {
  const { data, fetchNextPage, hasNextPage } = useInfiniteQuery(['items'], fetchItems, {
    getNextPageParam: (lastPage) => lastPage.nextPage,
  });

  return (
    <div>
      {data.pages.map((page) =>
        page.items.map((item) => <div key={item.id}>{item.name}</div>)
      )}
      {hasNextPage && <button onClick={fetchNextPage}>Load More</button>}
    </div>
  );
}

*React Query DevTools
*
React Query includes a handy DevTools interface that provides insight into your queries' state. You can install it and include it in your app like so:

import { ReactQueryDevtools } from '@tanstack/react-query-devtools';

function App() {
  return (
    <QueryClientProvider client={queryClient}>
      <MyComponent />
      <ReactQueryDevtools initialIsOpen={false} />
    </QueryClientProvider>
  );
}

Conclusion
React Query is a game-changer for managing server-side state in React applications. Its features like caching, background updates, and DevTools make it a must-have for modern React projects. By reducing boilerplate and improving developer experience, React Query allows you to focus more on building great features and less on managing server state.

Have you tried React Query in your projects? Share your experiences in the comments below!