Understanding React Query DevTools

For many developers, React Query is an essential tool to manage serve state in React apps.

If you want to really harness React Query, though, you’re need to understand its tooling. React Query DevTools help you debug and optimize your queries. In this post we’ll go over the main functionalities and features of React Query DevTools.

What is React Query DevTools?

React Query DevTools is a set of tools designed to help developers understand, debug, and optimize their usage of React Query. With a UI that integrates seamlessly into your application during development, it offers a real-time view into your queries' states, caching behaviors, and more.

How to set up React Query DevTools

Integrating React Query DevTools is pretty easy. Here's a simple setup:

import { ReactQueryDevtools } from 'react-query/devtools'

function MyApp({ Component, pageProps }) {
  return (
    <>
      <Component {...pageProps} />
      {/* Add the DevTools component */}
      <ReactQueryDevtools initialIsOpen={false} />
    </>
  );
}

You can hook up a button or keyboard shortcut to tools the visibility of the devtools.

Features of React Query DevTools

Query explorer

This feature offers a list of all the queries in use. You can view their status (loading, success, error), data, and other relevant details. Clicking on a query reveals further insights into its cache lifecycle, refetch interval, and more.

Cache management

React Query DevTools allows you to inspect the current cache and even manipulate it. You can remove specific queries or clear the entire cache, helping simulate and debug various scenarios.

Timeline and events

This is a visual representation of when your queries are fetching, updating, or becoming stale. It's particularly helpful to understand the sequence of events, pinpoint inefficiencies, or debug unexpected behaviors.

Mutation inspector

Not only can you inspect queries, but you can also get insights into mutations. This includes the status, variables used, and the resulting data or errors.

Tips for debugging with React Query DevTools

Filtering queries

As your application grows, the list of queries might become overwhelming. Use the search bar to filter queries by their keys.

Pause/resume polling

For queries that poll regularly, you can pause and resume polling to aid debugging.

Force refetch

If you suspect an issue with a specific query or want to manually trigger it, you can do so with the 'refetch' button.

Analyze cache

Periodically inspect the cache to ensure data is stored and updated as expected. Unexpected cache behaviors often hint at issues in query configurations.

Common use cases for React Query DevTools

Debugging stale data

If you suspect data is becoming stale unexpectedly, use DevTools to inspect the query's stale time and refetch intervals.

Optimizing performance

By monitoring the timeline, you can spot unnecessary refetches or overlapping queries. This can guide optimizations to reduce network requests and improve app responsiveness.

Error handling

When mutations or queries fail, DevTools provides insights into the error, which can guide your error-handling strategies.