How can I implement persistent state in my React app using React Query?

How can I implement persistent state in my React app using React Query?

You can implement persistent state in your React app by using React Query's built-in caching and synchronization features. This allows you to store data in local storage or session storage.

Can you show me a code example of how to do that?

Sure! You can use the useQuery hook along with a custom queryFn to fetch data and then save it to local storage. Here's a simple example:

import { useQuery } from 'react-query';

const fetchData = async () => {
  const response = await fetch('/api/data');
  return response.json();
};

const usePersistentQuery = () => {
  return useQuery('data', fetchData, {
    initialData: () => {
      return JSON.parse(localStorage.getItem('data')) || undefined;
    },
    onSuccess: (data) => {
      localStorage.setItem('data', JSON.stringify(data));
    },
  });
};

This code fetches data and stores it in local storage.

What if I want to clear the persistent state?

You can clear the persistent state by removing the item from local storage. You can do this in a function that you call when you want to reset the state:

const clearPersistentState = () => {
  localStorage.removeItem('data');
};

Just call clearPersistentState() whenever you need to reset the data.