Lambda handler split by HTTP method

common.ts

import { APIGatewayEvent, APIGatewayProxyHandler, Callback, Context } from "aws-lambda";

export function RestHandler(
  onCreate?: APIGatewayProxyHandler,
  onUpdate?: APIGatewayProxyHandler,
  onDelete?: APIGatewayProxyHandler
) {
  return async (event: APIGatewayEvent, context: Context, callback: Callback) => {
    switch (event.httpMethod) {
      case "DELETE":
        return onDelete(event, context, callback);
      case "PATCH":
        return onUpdate(event, context, callback);
      case "POST":
        return onCreate(event, context, callback);
    }
  };
}

handler.ts

import { RestHandler } from "common";

function deleteHandler(event: APIGatewayEvent, context: Context, callback: Callback) {
  // Do something
}

function createHandler(event: APIGatewayEvent, context: Context, callback: Callback) {
  // Do something
}

function updateHandler(event: APIGatewayEvent, context: Context, callback: Callback) {
  // Do something
}

// This is the only entry point exported for the Lambda. It will call the correct create, update, delete method base on the event.httpMethod
export const handler = RestHandler(createHandler, updateHandler, deleteHandler)