Client API

The NextAuth.js client library makes it easy to interact with sessions from React applications.

Example Session Object

{
user: {
name: string,
email: string,
image: uri
},
accessToken: string,
expires: "YYYY-MM-DDTHH:mm:ss.SSSZ"
}
tip

The session data returned to the client does not contain sensitive information such as the Session Token or OAuth tokens. It contains a minimal payload that includes enough data needed to display information on a page about the user who is signed in for presentation purposes (e.g name, email, image).

You can use the session callback to customize the session object returned to the client if you need to return additional data in the session object.

useSession()

  • Client Side: Yes
  • Server Side: No

The useSession() React Hook in the NextAuth.js client is the easiest way to check if someone is signed in.

It works best when the <Provider> is added to pages/_app.js.

Example

import { useSession } from 'next-auth/client'
export default () => {
const [ session, loading ] = useSession()
return <>
{session && <p>Signed in as {session.user.email}</p>}
{!session && <p><a href="/api/auth/signin">Sign in</a></p>}
</>
}

getSession()

  • Client Side: Yes
  • Server Side: Yes

NextAuth.js provides a getSession() method which can be called client or server side to return a session.

It calls /api/auth/session and returns a promise with a session object, or null if no session exists.

Client Side Example

async function myFunction() {
const session = await getSession()
/* ... */
}

Server Side Example

import { getSession } from 'next-auth/client'
export default async (req, res) => {
const session = await getSession({ req })
/* ... */
res.end()
}
note

When calling getSession() server side, you need to pass {req} or context object.

The tutorial securing pages and API routes shows how to use getSession() in server side calls.

getCsrfToken()

  • Client Side: Yes
  • Server Side: Yes

The getCsrfToken() method returns the current Cross Site Request Forgery Token (CSRF Token) required to make POST requests (e.g. for signing in and signing out).

You likely only need to use this if you are not using the built-in signIn() and signOut() methods.

Client Side Example

async function myFunction() {
const csrfToken = await getCsrfToken()
/* ... */
}

Server Side Example

import { getCsrfToken } from 'next-auth/client'
export default async (req, res) => {
const csrfToken = await getCsrfToken({ req })
/* ... */
res.end()
}

getProviders()

  • Client Side: Yes
  • Server Side: Yes

The getProviders() method returns the list of providers currently configured for sign in.

It calls /api/auth/providers and returns a list of the currently configured authentication providers.

It can be use useful if you are creating a dynamic custom sign in page.

API Route

pages/api/example.js
import { getSession } from 'next-auth/client'
export default async (req, res) => {
const session = await getSession({ req })
console.log('Session', session)
res.end()
}

signIn()

  • Client Side: Yes
  • Server Side: No

Using the signIn() method ensures the user ends back on the page they started on after completing a sign in flow. It will also handle CSRF Tokens for you automatically when signing in with email.

The signIn() method can be called from the client in different ways, as shown below.

Redirects to sign in page when clicked

import { signIn } from 'next-auth/client'
export default () => (
<button onClick={signIn}>Sign in</button>
)

Starts Google OAuth sign-in flow when clicked

import { signIn } from 'next-auth/client'
export default () => (
<button onClick={() => signIn('google')}>Sign in with Google</button>
)

Starts Email sign-in flow when clicked

When using it with the email flow, pass the target email as an option.

import { signIn } from 'next-auth/client'
export default ({ email }) => (
<button onClick={() => signIn('email', { email })}>Sign in with Email</button>
)

Specifying a callbackUrl

The callbackUrl specifies to which URL the user will be redirected after signing in. It defaults to the current URL of a user.

You can specify a different callbackUrl by specifying it as the second argument of signIn(). This works for all providers.

e.g.

  • signIn(null, { callbackUrl: 'http://localhost:3000/foo' })
  • signIn('google', { callbackUrl: 'http://localhost:3000/foo' })
  • signIn('email', { email, callbackUrl: 'http://localhost:3000/foo' })

The URL must be considered valid by the redirect callback handler. By default it requires the URL to be an absolute URL at the same hostname, or else it will redirect to the homepage. You can define your own redirect callback to allow other URLs, including supporting relative URLs.

signOut()

  • Client Side: Yes
  • Server Side: No

Using the signOut() method ensures the user ends back on the page they started on after completing the sign out flow. It also handles CSRF tokens for you automatically.

It reloads the page in the browser when complete.

import { signOut } from 'next-auth/client'
export default () => (
<button onClick={signOut}>Sign out</button>
)

Specifying a callbackUrl

As with the signIn() function, you can specify a callbackUrl parameter by passing it as an option.

e.g. signOut({ callbackUrl: 'http://localhost:3000/foo' })

The URL must be considered valid by the redirect callback handler. By default this means it must be an absolute URL at the same hostname (or else it will default to the homepage); you can define your own custom redirect callback to allow other URLs, including supporting relative URLs.

Provider

Using the supplied React <Provider> allows instances of useSession() to share the session object across components, by using React Context under the hood.

This improves performance, reduces network calls and avoids page flicker when rendering. It is highly recommended and can be easily added to all pages in Next.js apps by using pages/_app.js.

pages/_app.js
import { Provider } from 'next-auth/client'
export default function App ({ Component, pageProps }) => {
return (
<Provider session={pageProps.session}>
<Component {...pageProps} />
</Provider>
)
}

If you pass the session page prop to the <Provider> – as in the example above – you can avoid checking the session twice on pages that support both server and client side rendering.

Options

The session state is automatically synchronized across all open tabs/windows and they are all updated whenever they gain or lose focus or the state changes in any of them (e.g. a user signs in or out).

If you have session expiry times of 30 days (the default) or more then you probably don't need to change any of the default options in the Provider. If you need to, you can can trigger an update of the session object across all tabs/windows by calling getSession() from a client side function.

However, if you need to customise the session behaviour and/or are using short session expiry times, you can pass options to the provider to customise the behaviour of the useSession() hook.

pages/_app.js
import { Provider } from 'next-auth/client'
export default function App ({ Component, pageProps }) => {
return (
<Provider session={pageProps.session}
options={{
clientMaxAge: 60 // Re-fetch session if cache is older than 60 seconds
keepAlive: 5 * 60 // Send keepAlive message every 5 minutes
}}
>
<Component {...pageProps} />
</Provider>
)
}
note

These options have no effect on clients that are not signed in.

Every tab/window maintains it's own copy of the local session state; the session it is not stored in shared storage like localStorage or sessionStorage. Any update in one tab/window triggers a message to other tabs/windows to update their own session state.

Using low values for clientMaxAge or keepAlive will increase network traffic and load on authenticated clients and may impact hosting costs and performance.

Client Max Age

The clientMaxAge option is the maximum age a session data can be on the client before it is considerd stale.

When clientMaxAge is set to 0 (the default) the cache will always be used when useSession is called and only explicit calls made to get the session status (i.e. getSession()) or event triggers, such as signing in or out in another tab/window, or a tab/window gaining or losing focus, will trigger an update of the session state.

If set to any value other than zero, it specifies in seconds the maxium age of session data on the client before the useSession() hook will call the server again to sync the session state.

Unless you have a short session expiry time (e.g. < 24 hours) you probably don't need to change this option. Setting this option to too short a value will increase load (and potentially hosting costs).

The value for clientMaxAge should always be lower than the value of the session maxAge option.

Keep Alive

The keepAlive option is how often the client should contact the server to avoid a session expirying.

When keepAlive is set to 0 (the default) it will not send a keep alive message.

If set to any value other than zero, it specifies in seconds how often the client should contact the server to update the session state. If the session state has expired when it is triggered, all open tabs/windows will be updated to reflect this.

The value for keepAlive should always be lower than the value of the session maxAge option.

note

See the Next.js documentation for more information on _app.js in Next.js applications.

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