Expressjs-utils NPM

expressjs-utils

This module contains a set of utilities that make our life easier while writing express apps. The minimum supported node version for this lib is v8.6.0.

Installation

$ yarn add expressjs-utils

$ npm install expressjs-utils

Usage

const utils = require("expressjs-utils");

start

start(app, port, env)

starts the express server unless you're in the test env

// starts your app on port 8082 with environment set to 'test'
utils.start(app, 8082, "test");

static

static(app, path)

mounts the static, /public folder

// assuminc your public folder is located at '/../../public'
utils.static(app);

// if it is located somewhere else, just pass the path, relative to the current file.
utils.static(app, "/../public");

getRouter

getRouter(app, prefix)

returns a router that prefixes all routes at /prefix & /prefix/vX or /vX, where X is a specific version of your api. Use it for API versioning & when you need a common prefix. If no API version is passed, that is vX is not present in the url, it will be set to 0 by default. You can access the API Version using req.apiVersion.

  let express = require('express');

  // You can also pass express to getRouter function
  let router = utils.getRouter(app, 'api', express);
  //OR use the default express from the library to create the router
  let router = utils.getRouter(app, 'api');

  router.get('/cars', (req, res, next) => {
    return res.json({...});
  });

  // Possible endpoint formats
  /api/v1/cars //req.apiVersion will be 1 here
  /api/cars //req.apiVersion will be 0 here

  let router = utils.getRouter(app, '');
  router.get('/people', (req, res, next) => {
    return res.json({...});
  });

  // Possible endpoint formats
  /v1/people //req.apiVersion will be 1 here
  /people
  //req.apiVersion will be 0 here

errorHandler

errorHandler(app, logger) provides a generic error handler that can be used at the "end" of your app logger is optional. If you want to use a logger that will give you a bit more details, you should just get our open-source logger and pass it to the error handler and we will use it, instead of console.error, to log the error.

// Add this after all your routes
utils.errorHandler(app);

// Then in any route you can simply call next(err) whenever an error occurs
router.post("/cars", async (req, res, next) => {
  try {
    let result = await getCars();
  } catch (err) {
    next(err);
  }
});

httpError

httpError(code=500, message='Internal Server Error')

Throws an error that has an HTTP status code. These errors are public-friendly, therefore their message can be displayed on the API.

The message parameter can either be a string or an object. For example,

let err = utils.httpError(404, { userMessage: "This product was not found. Please try other products" });

Then, on the client you will be able to do err.userMessage providing that you use our errorHandler(). Otherwise, you'll need to access your custom object via the data attribute of the error object: err.data.userMessage

// if you are using the error handler above, you can do something like this in
// any of your API endpoint
router.get("/users/:id", async (req, res, next) => {
  try {
    let user = await getUser(req.params.id);

    if (!user) {
      return next(utils.httpError(404, "Not found"));
    }
  } catch (err) {
    next(err);
  }
});

serveCSV

serveCSV(res, filename, rows)

returns a downloadable csv file built from "rows" which is an array of objects.

router.get("/data", async (req, res, next) => {
  let data = [{ name: "Test 0", age: 3 }, { name: "Test 1", age: 4 }];

  return utils.serveCSV(res, "data.csv", data);
});