Book Image

State Management with React Query

By : Daniel Afonso
Book Image

State Management with React Query

By: Daniel Afonso

Overview of this book

State management, a crucial aspect of the React ecosystem, has gained significant attention in recent times. While React offers various libraries and tools to handle state, each with different approaches and perspectives, one thing is clear: state management solutions for handling client state are not optimized for dealing with server state. React Query was created to address this issue of managing your server state, and this guide will equip you with the knowledge and skills needed to effectively use React Query for state management. Starting with a brief history of state management in the React ecosystem, you’ll find out what prompted the split from a global state to client and server state and thus understand the need for React Query. As you progress through the chapters, you'll see how React Query enables you to perform server state tasks such as fetching, caching, updating, and synchronizing your data with the server. But that’s not all; once you’ve mastered React Query, you’ll be able to apply this knowledge to handle server state with server-side rendering frameworks as well. You’ll also work with patterns to test your code by leveraging the testing library and Mock Service Worker. By the end of this book, you'll have gained a new perspective of state and be able to leverage React Query to overcome the obstacles associated with server state.
Table of Contents (14 chapters)
Part 1: Understanding State and Getting to Know React Query
Part 2: Managing Server State with React Query

Removing keepPreviousData and using placeholderData

The keepPreviousData option and the isPreviousData flags have been removed. This is because they did almost the same task as the placeholderData option and the isPlaceholderData flag.

So that placeholderData can fully do exactly the same thing as keepPreviousData, the previous query data was added as an argument to the placeholderData function. This now means that by leveraging the keepPreviousData custom function from React Query, useQuery will allow placeholderData to work the same way as keepPreviousData did previously.

Let us see how our PaginatedQuery code changes in v5:

import { useQuery, keepPreviousData } from "@tanstack/react-query";
const PaginatedQuery = () => {
  const { isPending, isError, error, data, isFetching,
    isPlaceholderData } =
      queryKey: userKeys.paginated(page),