RTK Query reference

What is RTK Query?

RTK (Redux Toolkit) Query is a data fetching and caching tool that aims to simplify common data fetching and caching use cases. It’s part of @reduxjs/toolkit.

How to use

1. Create an API slice

With RTK Query, you typically create one API slice per base URL and define all the endpoints for that slice in one place.

import { createApi, fetchBaseQuery } from '@reduxjs/toolkit/query/react'
import { Pokemon } from './types'

// Define a service using a base URL and expected endpoints
export const pokemonApi = createApi({
  reducerPath: 'pokemonApi',
  baseQuery: fetchBaseQuery({ baseUrl: 'https://pokeapi.co/api/v2/' }),
  endpoints: (builder) => ({
    getPokemonByName: builder.query<Pokemon, string>({
      query: (name) => `pokemon/${name}`,
    }),
  }),
})

// Export hooks for usage in functional components, which are
// auto-generated based on the defined endpoints
export const { useGetPokemonByNameQuery } = pokemonApi

2. Configure the store

Add the generated API slice reducer to your Redux store:

import { configureStore } from '@reduxjs/toolkit'
// Or from '@reduxjs/toolkit/query/react'
import { setupListeners } from '@reduxjs/toolkit/query'
import { pokemonApi } from './services/pokemon'

export const store = configureStore({
  reducer: {
    // Add the generated reducer as a specific top-level slice
    [pokemonApi.reducerPath]: pokemonApi.reducer,
  },
  // Adding the api middleware enables caching, invalidation, polling,
  // and other useful features of `rtk-query`.
  middleware: (getDefaultMiddleware) =>
    getDefaultMiddleware().concat(pokemonApi.middleware),
})

// optional, but required for refetchOnFocus/refetchOnReconnect behaviors
// see `setupListeners` docs - takes an optional callback as the 2nd arg for customization
setupListeners(store.dispatch)

3. Wrap your application with a Provider

import * as React from 'react'
import { render } from 'react-dom'
import { Provider } from 'react-redux'

import App from './App'
import { store } from './app/store'

const rootElement = document.getElementById('root')
render(
  <Provider store={store}>
    <App />
  </Provider>,
  rootElement
)

4. Use hooks in components

import * as React from 'react'
import { useGetPokemonByNameQuery } from './services/pokemon'

export default function App() {
  // Using a query hook automatically fetches data and returns query values
  const { data, error, isLoading } = useGetPokemonByNameQuery('bulbasaur')
  // Individual hooks are also accessible under the generated endpoints:
  // const { data, error, isLoading } = pokemonApi.endpoints.getPokemonByName.useQuery('bulbasaur')
  
  // render UI based on data and loading state
}

Reasons to use RTK Query

Integrates with Redux DevTools, allowing you to see the history of state changes in your application. RTK Query dispatches a Redux action when each network request is started, fulfilled, or failed. This makes it easy to see what is going on in your app and how network requests affect the state.

Sources

• RTK Query tutorial – Redux Toolkit docs
• RTK Query overview – Redux Toolkit docs