@serverless-guy/lambda

A small lambda wrapper that lets you write cleaner and maintainable lambda function

Status

Installation

You can start by installing this library using the command below:

npm i --save @serverless-guy/lambda

Basic Usage

In the example below, the handler would log the event first, then context. Afterwards, it will return the event as response.

import { wrapper } from "@serverless-guy/lambda";

export const handler = wrapper(someHandler);

/**
 * Handler that is accepted by our lambda wrapper
 * @param request.event Lambda's event object
 * @param request.context Lambda's context object
 * @param response handy function to return a response
 * @return response
 */
function someHandler(request, response) {
  const { event, context } = request;

  console.log(event);
  console.log(context);

  return response(event);
}

Using middleware

import { wrapper } from "@serverless-guy/lambda";

export const handler = wrapper(someHandler);

handler.pushMiddleware(checkBody);

/**
 * Function that parse object string to object
 * @param body object string
 * @return parsed object
 */
function parse(body) {
  if (!body) {
    return {}
  }

  return JSON.parse(body);
}

/**
 * Middleware that is accepted by our lambda wrapper
 * @param request.event Lambda's event object
 * @param request.context Lambda's context object
 * @param next middleware/handler next to this middleware
 * @return next
 */
export function checkBody(request, next) {
  const { event } = request;

  const body = parse(event.body);

  if (!body.sampleValue1) {
    throw new Error("Validation Failed");
  }

  return next(request);
}


/**
 * Handler that is accepted by our lambda wrapper
 * @param request.event Lambda's event object
 * @param request.context Lambda's context object
 * @param response handy function to return a response
 * @return response
 */
function someHandler(request, response) {
  const { event, context } = request;

  const body = JSON.parse(event.body);
  console.log(context);

  return response({ message: body.sampleValue1 });
}

Using custom response function

import { wrapper } from "@serverless-guy/lambda";

export const handler = wrapper(someHandler);

handler.setResponseTemplate(customResponseTemplate);

/**
 * Custom response function that is accepted by our lambda wrapper
 * @param data object to be appended as response's body
 * @param statusCode HTTP status code
 * @param headers HTTP headers
 * @return APIGatewayProxyResult
 */
function customResponseTemplate(data, statusCode = 200, headers = {}) {
    // do something
    data.returnedOn = new Date();

    return {
    body: JSON.stringify(data),
    headers: {
      "Access-Control-Allow-Origin": "*",
      ...headers
    },
    statusCode
  };
}

/**
 * Handler that is accepted by our lambda wrapper
 * @param request.event Lambda's event object
 * @param request.context Lambda's context object
 * @param response handy function to return a response
 * @return response
 */
function someHandler(request, response) {
  const { event, context } = request;

  console.log(event);
  console.log(context);

  return response(event);
}

Using custom error response function

import { wrapper } from "@serverless-guy/lambda";
 
export const handler = wrapper(someHandler);

handler.setCatchTemplate(customCatchResponseTemplate);

/**
 * Custom error function that is accepted by our lambda wrapper
 * @param error Error object
 * @param request event and context
 * @param responseFunction Response function
 * @return APIGatewayProxyResult
 */
function customCatchResponseTemplate(error, request, responseFunction) {
  const errorResponseObject = {
    errorCode:    error.name,
    errorMessage: error.message
  };

  return response(errorResponseObject, 418); /** I'm a f***ing teapot */
}

/**
 * Handler that is accepted by our lambda wrapper
 * @param request.event Lambda's event object
 * @param request.context Lambda's context object
 * @param response handy function to return a response
 * @return response
 */
function someHandler(request, response) {
  const { event, context } = request;

  console.log(event);
  console.log(context);

  return response(event);
}

Check out our documentation page to see more examples.