Creating a database adapter

Using a custom adapter you can connect to any database backend or even several different databases.

Creating a custom adapter can be considerable undertaking and will require some trial and error and some reverse engineering using the built-in adapters for reference.

How to create an adapter

From an implementation perspective, an adapter in NextAuth.js is a function which returns an async getAdapter() method, which in turn returns a Promise with a list of functions used to handle operations such as creating user, linking a user and an OAuth account or handling reading and writing sessions.

It uses this approach to allow database connection logic to live in the getAdapter() method. By calling the function just before an action needs to happen, it is possible to check database connection status and handle connecting / reconnecting to a database as required.

See the code below for practical example.

Required methods

These methods are required for all sign in flows:

  • createUser
  • getUser
  • getUserByEmail
  • getUserByProviderAccountId
  • linkAccount
  • createSession
  • getSession
  • updateSession
  • deleteSession
  • updateUser

These methods are required to support email / passwordless sign in:

  • createVerificationRequest
  • getVerificationRequest
  • deleteVerificationRequest

Unimplemented methods

These methods will be required in a future release, but are not yet invoked:

  • getUserByCredentials
  • deleteUser
  • unlinkAccount

Example code

const Adapter = (config, options = {}) => {
async function getAdapter (appOptions) {
async function createUser (profile) {
return null
}
async function getUser (id) {
return null
}
async function getUserByEmail (email) {
return null
}
async function getUserByProviderAccountId (
providerId,
providerAccountId
) {
return null
}
async function getUserByCredentials (credentials) {
return null
}
async function updateUser (user) {
return null
}
async function deleteUser (userId) {
return null
}
async function linkAccount (
userId,
providerId,
providerType,
providerAccountId,
refreshToken,
accessToken,
accessTokenExpires
) {
return null
}
async function unlinkAccount (
userId,
providerId,
providerAccountId
) {
return null
}
async function createSession (user) {
return null
}
async function getSession (sessionToken) {
return null
}
async function updateSession (
session,
force
) {
return null
}
async function deleteSession (sessionToken) {
return null
}
async function createVerificationRequest (
identifier,
url,
token,
secret,
provider
) {
return null
}
async function getVerificationRequest (
identifier,
token,
secret,
provider
) {
return null
}
async function deleteVerificationRequest (
identifier,
token,
secret,
provider
) {
return null
}
return Promise.resolve({
createUser,
getUser,
getUserByEmail,
getUserByProviderAccountId,
getUserByCredentials,
updateUser,
deleteUser,
linkAccount,
unlinkAccount,
createSession,
getSession,
updateSession,
deleteSession,
createVerificationRequest,
getVerificationRequest,
deleteVerificationRequest
})
}
return {
getAdapter
}
}
export default {
Adapter
}
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