Amplify allows the creation of entities through generated code. I’d like to harness this to create several entities at once.

When a user creates an entity, say Event,

const Event = a
  .model({
    id: a.id().required(),
    title: a.string(),
    eventOwnerId: a.id().required(),
    eventOwner: a.belongsTo("EventOwner", "eventOwnerId"),
    ...
  })
  .authorization((allow) => [allow.owner()]);

where

const EventOwner = a
  .model({
    id: a.id().required(),
    userId: a.id().required(), // should be associated with a user
    eventId: a.id().required(),
    events: a.hasMany("Event", "eventOwnerId"),
  })
  .authorization((allow) => [allow.owner()]);,

a given property on that event, say eventOwner should be automatically populated through the following process.

• If an EventOwner is associated with the user who submitted the createEvent mutation, the created event will automatically be associated via that EventOwner via its eventOwnerId.
• If an EventOwner is not associated with the user who submitted the createEvent mutation, the created event will automatically generate a EventOwner entity. And, that EventOwner should automatically be associated with the newly created Event.

I believe this should be accomplished through a lambda function. So, I believe should have

• an amplify/functions/pre-event-creation/resource.ts with `import { defineFunction } from “@aws-amplify/backend”;

export const preEventCreation = defineFunction({name: "pre-event-creation",});`

• and an amplify/functions/pre-event-creation/handler.ts, which I suspect should look something like:

import { Amplify } from "aws-amplify";
import { generateClient } from "aws-amplify/data";
import type { PostConfirmationTriggerHandler } from "aws-lambda";
import { type Schema } from "../../data/schema";
import { preEventCreation } from "./resource";
import { env } from "$amplify/env/post-confirmation";

Amplify.configure(
  {
    API: {
      GraphQL: {
        endpoint: env.AMPLIFY_DATA_GRAPHQL_ENDPOINT,
        region: env.AWS_REGION,
        defaultAuthMode: "iam",
      },
    },
  },
  {
    Auth: {
      credentialsProvider: {
        getCredentialsAndIdentityId: async () => ({
          credentials: {
            accessKeyId: env.AWS_ACCESS_KEY_ID,
            secretAccessKey: env.AWS_SECRET_ACCESS_KEY,
            sessionToken: env.AWS_SESSION_TOKEN,
          },
        }),
        clearCredentialsAndIdentityId: () => {
          /* noop */
        },
      },
    },
  }
);

const client = generateClient<Schema>({
  authMode: "iam",
});

export const handler: PostConfirmationTriggerHandler = async (event) => {
  await client.graphql({
    query: preEventCreation,
    variables: {
      input: {
        email: event.request.userAttributes.email,
        profileOwner: `${event.request.userAttributes.sub}::${event.userName}`,
      },
    },
  });

  return event;
};

Specifically, I’d like to know what to add to the handler. Thanks in advance!

I’ve tried variations on the PostConfirmationTriggerHandler from the amplify docs, but haven’t made much headway.