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

Fetching dependent queries with useQuery

Sometimes, during our development process, we need to have values that are returned from one query that we can use in another query or have a query execution depend on a previous query. When this happens, we need to have what is called a dependent query.

React Query allows you to make a query depend on others via the enabled option.

This is how you can do it:

const App = () => {
  const { data: firstQueryData } = useQuery({
    queryKey: ["api"],
    queryFn: fetchData,
  const canThisDependentQueryFetch = firstQueryData?.hello
    !== undefined;
  const { data: dependentData } = useQuery({
    queryKey: ["dependentApi", firstQueryData?.hello],
    queryFn: fetchDependentData,
    enabled: canThisDependentQueryFetch,