Example of a bad lambda function handler not using Hexagonal Architectures

create-order.ts

import * as AWS from 'aws-sdk'; // <-- service specific

// <-- lambda specific
import {
  APIGatewayEvent,
  APIGatewayProxyHandler,
  APIGatewayProxyResult,
} from 'aws-lambda';

import { OrderCreate } from '../../../../types';
import { v4 as uuid } from 'uuid';

const dynamoDb = new AWS.DynamoDB.DocumentClient(); // <-- service specific
const eventBridge = new AWS.EventBridge(); // <-- service specific

export const handler: APIGatewayProxyHandler = async (
  // <-- lambda function specific
  event: APIGatewayEvent
): Promise<APIGatewayProxyResult> => {
  // <-- lambda function specific
  try {
    const correlationId = uuid();
    const method = 'create-order.handler';
    const prefix = `${correlationId} - ${method}`;

    console.log(`${prefix} - started`);

    if (!event?.body) throw new Error('no body on the event'); // <-- lambda specific

    const { id, quantity } = JSON.parse(event.body); // <-- lambda specific

    if (quantity === 0) throw new Error('quantity of 0 not valid'); // <-- domain specific

    const ordersTable = process.env.TABLE_NAME as string; // <-- service specific

    // <-- domain specific
    const order: OrderCreate = {
      id,
      quantity,
      created: new Date().toISOString(),
      updated: new Date().toISOString(),
    }; // <-- domain specific

    const params: AWS.DynamoDB.DocumentClient.PutItemInput = {
      TableName: ordersTable,
      Item: order,
    }; // <-- service specific

    console.log(`${prefix} - creating order: ${JSON.stringify(order)}`);

    await dynamoDb.put(params).promise(); // <-- service specific

    // <-- service specific
    const orderCreatedEvent: AWS.EventBridge.PutEventsRequestEntry = {
      Detail: JSON.stringify(order),
      DetailType: 'OrderCreated',
      EventBusName: 'OrderEventBus',
      Source: 'com.service.order',
    };
    // <-- service specific

    const orderEvent: AWS.EventBridge.PutEventsRequest = {
      Entries: [orderCreatedEvent],
    }; // <-- service specific

    // <-- service specific
    const result: AWS.EventBridge.PutEventsResponse = await eventBridge
      .putEvents(orderEvent)
      .promise();
    // <-- service specific

    console.log(`${prefix} - creating order event: ${JSON.stringify(result)}`);

    // <-- lambda function specific
    return {
      statusCode: 201,
      body: JSON.stringify(order),
    };
    // <-- lambda function specific
  } catch (error) {
    console.log(error);
    throw error;
  }
};