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Global Configuration

Global Configuration

The context SWRConfig can provide global configurations (options) for all SWR hooks.

<SWRConfig value={options}>
  <Component/>
</SWRConfig>

In this example, all SWR hooks will use the same fetcher provided to load JSON data, and refresh every 3 seconds by default:

import useSWR, { SWRConfig } from 'swr'
 
function Dashboard () {
  const { data: events } = useSWR('/api/events')
  const { data: projects } = useSWR('/api/projects')
  const { data: user } = useSWR('/api/user', { refreshInterval: 0 }) // override
 
  // ...
}
 
function App () {
  return (
    <SWRConfig 
      value={{
        refreshInterval: 3000,
        fetcher: (resource, init) => fetch(resource, init).then(res => res.json())
      }}
    >
      <Dashboard />
    </SWRConfig>
  )
}

Nesting Configurations

SWRConfig merges the configuration from the parent context. It can receive either an object or a functional configuration. The functional one receives the parent configuration as argument and returns a new configuration that you can customize yourself.

Object Configuration Example

import { SWRConfig, useSWRConfig } from 'swr'
 
function App() {
  return (
    <SWRConfig
      value={{
        dedupingInterval: 100,
        refreshInterval: 100,
        fallback: { a: 1, b: 1 },
      }}
    >
      <SWRConfig
        value={{
          dedupingInterval: 200, // will override the parent value since the value is primitive
          fallback: { a: 2, c: 2 }, // will merge with the parent value since the value is a mergeable object
        }}
      >
        <Page />
      </SWRConfig>
    </SWRConfig>
  )
}
 
function Page() {
  const config = useSWRConfig()
  // {
  //   dedupingInterval: 200,
  //   refreshInterval: 100,
  //   fallback: { a: 2,  b: 1, c: 2 },
  // }
}

Functional Configuration Example

import { SWRConfig, useSWRConfig } from 'swr'
 
function App() {
  return (
    <SWRConfig
      value={{
        dedupingInterval: 100,
        refreshInterval: 100,
        fallback: { a: 1, b: 1 },
      }}
    >
      <SWRConfig
        value={parent => ({
          dedupingInterval: parent.dedupingInterval * 5,
          fallback: { a: 2, c: 2 },
        })}
      >
        <Page />
      </SWRConfig>
    </SWRConfig>
  )
}
 
function Page() {
  const config = useSWRConfig()
  // {
  //   dedupingInterval: 500,
  //   fallback: { a: 2, c: 2 },
  // }
}

Extra APIs

Cache Provider

Besides all the options listed, SWRConfig also accepts an optional provider function. Please refer to the Cache section for more details.

<SWRConfig value={{ provider: () => new Map() }}>
  <Dashboard />
</SWRConfig>

Access To Global Configurations

You can use the useSWRConfig hook to get the global configurations, as well as mutate and cache:

import { useSWRConfig } from 'swr'
 
function Component () {
  const { refreshInterval, mutate, cache, ...restConfig } = useSWRConfig()
 
  // ...
}

Nested configurations will be extended. If no <SWRConfig> is used, it will return the default ones.

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