Custom message
You can use defineAuth and defineFunction to create an Amazon Cognito custom message AWS Lambda trigger thats sends an custom email or phone verification message, or a multi-factor authentication (MFA) code.
To get started, install @types/aws-lambda package that will be used to define the type of the handler:
npm add --save-dev @types/aws-lambdaNext, create a new directory and a resource file, amplify/auth/custom-message/resource.ts. Then, define the function with defineFunction:
import { defineFunction } from '@aws-amplify/backend';
export const customMessage = defineFunction({ name: "custom-message", resourceGroupName: 'auth'});Next, create the corresponding handler file, amplify/auth/custom-message/handler.ts, file with the following contents:
import type { CustomMessageTriggerHandler } from "aws-lambda";
export const handler: CustomMessageTriggerHandler = async (event) => { if (event.triggerSource === "CustomMessage_ForgotPassword") { const locale = event.request.userAttributes["locale"]; if (locale === "en") { event.response.emailMessage = `Your new one-time code is ${event.request.codeParameter}`; event.response.emailSubject = "Reset my password"; } else if (locale === "es") { event.response.emailMessage = `Tu nuevo código de un solo uso es ${event.request.codeParameter}`; event.response.emailSubject = "Restablecer mi contraseña"; } }
if (event.triggerSource === "CustomMessage_AdminCreateUser") { event.response.emailMessage = `Your username is ${event.request.usernameParameter} and your temporary password is ${event.request.codeParameter}`; event.response.emailSubject = 'Welcome to Example App'; }
return event;};Lastly, set the newly created function resource on your auth resource:
import { defineAuth } from '@aws-amplify/backend';import { customMessage } from "./custom-message/resource";
export const auth = defineAuth({ // ... triggers: { customMessage, }});After deploying the changes, whenever a user with user attribute locale set to es attempts to reset a password they will receive an email with a one-time code in Spanish.