fix(ts): improve events handlers' types

types/adapters.d.ts

@@ -1,6 +1,6 @@
 import { AppOptions } from "./internals"
 import { User, Profile, Session } from "."
-import { EmailConfig, SendVerificationRequest } from "./providers"
+import { EmailConfig } from "./providers"
 import { ConnectionOptions } from "typeorm"
 
 /** Legacy */

types/index.d.ts

@@ -1,4 +1,4 @@
-// Minimum TypeScript Version: 3.5
+// Minimum TypeScript Version: 3.6
 
 /// <reference types="node" />
 
@@ -111,7 +111,7 @@ export interface NextAuthOptions {
    *
    * [Documentation](https://next-auth.js.org/configuration/options#events) | [Events documentation](https://next-auth.js.org/configuration/events)
    */
-  events?: EventsOptions
+  events?: Partial<JWTEventCallbacks | SessionEventCallbacks>
   /**
    * By default NextAuth.js uses a database adapter that uses TypeORM and supports MySQL, MariaDB, Postgres and MongoDB and SQLite databases.
    * An alternative adapter that uses Prisma, which currently supports MySQL, MariaDB and Postgres, is also included.
@@ -350,20 +350,61 @@ export interface CookiesOptions {
 }
 
 /** [Documentation](https://next-auth.js.org/configuration/events) */
-export type EventType =
-  | "signIn"
-  | "signOut"
-  | "createUser"
-  | "updateUser"
-  | "linkAccount"
-  | "session"
-  | "error"
+export type EventCallback<MessageType = unknown> = (
+  message: MessageType
+) => Promise<void>
 
-/** [Documentation](https://next-auth.js.org/configuration/events) */
-export type EventCallback = (message: any) => Promise<void>
+/**
+ * If using a `credentials` type auth, the user is the raw response from your
+ * credential provider.
+ * For other providers, you'll get the User object from your adapter, the account,
+ * and an indicator if the user was new to your Adapter.
+ */
+export interface SignInEventMessage {
+  user: User
+  account: Account
+  isNewUser?: boolean
+}
 
-/** [Documentation](https://next-auth.js.org/configuration/events) */
-export type EventsOptions = Partial<Record<EventType, EventCallback>>
+export interface LinkAccountEventMessage {
+  user: User
+  providerAccount: Record<string, unknown>
+}
+
+/**
+ * The various event callbacks you can register for from next-auth
+ */
+export interface CommonEventCallbacks {
+  signIn: EventCallback<SignInEventMessage>
+  createUser: EventCallback<User>
+  updateUser: EventCallback<User>
+  linkAccount: EventCallback<LinkAccountEventMessage>
+  error: EventCallback
+}
+/**
+ * The event callbacks will take this form if you are using JWTs:
+ * signOut will receive the JWT and session will receive the session and JWT.
+ */
+export interface JWTEventCallbacks extends CommonEventCallbacks {
+  signOut: EventCallback<JWT>
+  session: EventCallback<{
+    session: Session
+    jwt: JWT
+  }>
+}
+/**
+ * The event callbacks will take this form if you are using Sessions
+ * and not using JWTs:
+ * signOut will receive the underlying DB adapter's session object, and session
+ * will receive the NextAuth client session with extra data.
+ */
+export interface SessionEventCallbacks extends CommonEventCallbacks {
+  signOut: EventCallback<Session | null>
+  session: EventCallback<{ session: Session }>
+}
+export type EventCallbacks = JWTEventCallbacks | SessionEventCallbacks
+
+export type EventType = keyof EventCallbacks
 
 /** [Documentation](https://next-auth.js.org/configuration/pages) */
 export interface PagesOptions {

types/tests/server.test.ts

@@ -1,12 +1,7 @@
-import Providers, {
-  AppProvider,
-  EmailConfig,
-  OAuthConfig,
-} from "next-auth/providers"
-import { Adapter, AdapterInstance } from "next-auth/adapters"
+import Providers, { OAuthConfig } from "next-auth/providers"
+import { Adapter } from "next-auth/adapters"
 import NextAuth, * as NextAuthTypes from "next-auth"
 import { IncomingMessage, ServerResponse } from "http"
-import * as JWTType from "next-auth/jwt"
 import { Socket } from "net"
 import { NextApiRequest, NextApiResponse } from "internals/utils"
 import { AppOptions } from "internals"
@@ -173,22 +168,25 @@ const allConfig: NextAuthTypes.NextAuthOptions = {
     },
   },
   events: {
-    async signIn(message) {
+    async signIn(message: NextAuthTypes.SignInEventMessage) {
       return undefined
     },
-    async signOut(message) {
+    async signOut(message: NextAuthTypes.Session | null) {
       return undefined
     },
-    async createUser(message) {
+    async createUser(message: NextAuthTypes.User) {
       return undefined
     },
-    async linkAccount(message) {
+    async updateUser(message: NextAuthTypes.User) {
       return undefined
     },
-    async session(message) {
+    async linkAccount(message: NextAuthTypes.LinkAccountEventMessage) {
       return undefined
     },
-    async error(message) {
+    async session(message: NextAuthTypes.Session) {
+      return undefined
+    },
+    async error(message: any) {
       return undefined
     },
   },

www/docs/configuration/events.md

@@ -7,17 +7,60 @@ Events are asynchronous functions that do not return a response, they are useful
 
 You can specify a handler for any of these events below, for debugging or for an audit log.
 
-```js title="pages/api/auth/[...nextauth].js"
-...
-  events: {
-    async signIn(message) { /* on successful sign in */ },
-    async signOut(message) { /* on signout */ },
-    async createUser(message) { /* user created */ },
-    async linkAccount(message) { /* account linked to a user */ },
-    async session(message) { /* session is active */ },
-    async error(message) { /* error in authentication flow */ }
-  }
-...
-```
-
-The content of the message object varies depending on the flow (e.g. OAuth or Email authentication flow, JWT or database sessions, etc) but typically contains a user object and/or contents of the JSON Web Token and other information relevant to the event.
+:::note
+Execution of your auth API will be blocked by an `await` on your event handler. If your event handler starts any burdensome work it should not block its own promise on that work.
+:::
+
+## Events
+
+### signIn
+
+Sent on successful sign in.
+
+The message will be an object and contain:
+
+- `user` (from your adapter or from the provider if a `credentials` type provider)
+- `account` (from your adapter or the provider)
+- `isNewUser` (whether your adapter had a user for this account already)
+
+### signOut
+
+Sent when the user signs out.
+
+The message object is the JWT, if using them, or the adapter session object for the session that is being ended.
+
+### createUser
+
+Sent when the adapter is told to create a new user.
+
+The message object will be the user.
+
+### updateUser
+
+Sent when the adapter is told to update an existing user. Currently this is only sent when the user verifies their email address.
+
+The message object will be the user.
+
+### linkAccount
+
+Sent when an account in a given provider is linked to a user in our userbase. For example, when a user signs up with Twitter or when an existing user links their Google account.
+
+The message will be an object and contain:
+
+- `user`: The user object from your adapter
+- `providerAccount`: The object returned from the provider.
+
+### session
+
+Sent at the end of a request for the current session.
+
+The message will be an object and contain:
+
+- `session`: The session object from your adapter
+- `jwt`: If using JWT, the token for this session.
+
+### error
+
+Sent when an error occurs
+
+The message could be any object relevant to describing the error.