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NodeJS project using ExpressJS to create an easy, secure and customisable API layer


npm install tree-house


All example code is written in ES6, but usage with ES5 will also properly work with Promise support.


Key Description Default value
port The application will run on this port 5000
bodyLimit Limit used for body-parser 10mb
apiKey An api key mapped to process.env to use throughout the application ga9ul2!MN36nyh64z4d5SC70jS
basePath The base path used to access all api routes process.env.BASE_PATH || '/api/v1'
https Configuration if you wish to start up an https server false
workers Number of workers in cluster mode 2
limiter Rate limiter {
trustProxy: true,
windowMs: 15 * 60 * 1000,
max: 100
delayMs: 0 // disabled


You can create a configuration object with own preferences and set this later on. See below in Basic Setup.
const myOwnConfiguration = {
    port: 3000,
    bodyLimit: '5mb',
    apiKey: 'myOwnApiKey',
    basePath: process.env.BASE_PATH || '/api',
HTTPS configuration (optional)
myOwnConfiguration = { 
  // Other configuration ...
  https: {
  	certificate: 'path_to_folder/test-ssl.cert',
 	privateKey: 'path_to_folder/test-ssl.key',
  	port: 5001

Getting started

Import the module from tree-house and create a new instance.

import { TreeHouse } from 'tree-house';
const application = new TreeHouse();

If you wish to overwrite the default application configuration, there are two options:

const application = new TreeHouse(myOwnConfiguration);


const application = new TreeHouse();


All controllers need to extend from BaseController which only provides one function: execute(res, fn)

It is required to provide a function that returns a promise

import { BaseController } from 'tree-house';

export class MyController extends BaseController {
    constructor() {
        this.myService = new MyService();  // Needed to use functions from this service

    // Get all employees
    getAllEmployees = (res, req) => this.execute(res, this.myService.getEmployees(res.body));

You need to make sure all functions declared in a controller that are being used by a route are automatically bound to the context of their Controller class by using fnName = (res, req) => { logic here... }. Dont't use fn(res, req) { logic here... }.

If you don't use this specific syntax, you won't be able to reference to this as the context of the MyController class. It will have become an instance of the Route class which won't allow you to call this.execute() or even this.myService.getEmployees().


All services need to extend from BaseService.

import { BaseService } from 'tree-house';

export class MyService extends BaseService {
    getEmployees() {
        // Get all employees from db and return them for example
        return myDb.executeQuery('SELECT * FROM EMPLOYEES');


All middleware needs to extend from BaseMiddleware which only provides one function: execute(req, res, next)

import { jwtAuthentication } from './main'; // Instance created via module tree-house-authentication
import { BaseMiddleware } from 'tree-house';

export class IsAuthenticated extends BaseMiddleware {
    execute(req, res, next) {
            .then((user) => {
                if (!user) throw new TreeError.Unauthorised();
                Object.assign(req, { session: { me: user } });


This is one of the most important parts of the application because all the controllers and policies need to be properly set here. You can create a route with path parameters or query parameters as if you would do in a regular expressJS application. Check the ExpressJS documentation for more information.

You need to create an array consisting of Route objects. A Route object has four parameters:

  • HTTP method
  • Path of the route (will be prepended by basePath from the configuration)
  • Function to call when the route gets triggered
  • Array of middleware (gets called in order before the function above) - optional
import { Route } from 'tree-house';
import { MyController } from './myController';
import { MyMiddleware } from './myMiddleware';

const myController = new MyController();
const myMiddleware = new MyMiddleware();
const myRoutes = [
    new Route('GET', '/employees', myController.getAllEmployees, [myMiddleware])

Set routes onto the main application



Install the tree-house-authentication module using npm install tree-house-authentication.

Error handler

There is a default error handler built in, but you can provide your own custom error handler if you want to. The only requirement is that it will need to extend from BaseErrorHandler and have an execute(error, req, res, next){} function. This is just a basic express error middleware implementation.


import { BaseErrorHandler } from 'tree-house';

export default class MyCustomErrorHandler extends BaseErrorHandler {
    execute(req, res, next) {
      if (err.statusCode) {
        res.json({ errorMessage: err.message, errorCode: err.code });
      } else {
const myCustomErrorHandler = new MyCustomErrorHandler();

Make sure to set the error handler before setting the routes!


All errors need to extend from BaseError. Treehouse provides some errors out of the box, and you can import them via import { TreeError } from 'tree-house'.

throw new TreeError.BadRequest('BAD_REQUEST', 'This is a bad request');
throw new TreeError.Unauthorised('NOT_AUTHORISED', 'You are not authorized to perform this action');
throw new TreeError.Server('SERVER_ERROR', 'Something went wrong');

throw new TreeError.NotFound('NOT_FOUND', 'The resource could not be found.');

throw new TreeError.Validation('INVALID_REQUEST', 'Validation error');
Predefined errors:
Error Default Message Default code Status
BadRequest This call is not valid, and thereby a bad request. BAD_REQUEST 400
Unauthorised You are not authorised to make this call. NOT_AUTHORISED 401
NotFound The resource could not be found. NOT_FOUND 404
Server Something went wrong. Our technicians are working on it! SERVER_ERROR 500
Validation Validation error. INVALID_REQUEST 400

Fire up them engines!

Start up the expressJS server after you've configured everything:


Cluster mode

The application will start in cluster mode by default. You can disable this by starting the application via application.fireUpEngines(false).

Use the instance throughout the application

It's best to use the same instance you've created in your main file throughout your whole application. The best way to achieve this is exporting the instance via module.exports:

module.exports.application = application;

This will allow you to use the same instance in all of your files via proper ES6 imports:

import { application } from './main';

// Call all functions and variables via this instance

Swagger integration

We provide swagger integration out of the box using swagger-ui-express. We only support YAML files at the moment to be served. You can call this function as many times as you want, when you have multiple swagger definitions or wish to use multiple routes for example.

const properties = {
  host: '',
  schemes: [],
application.setDocumentation('/route-to-docs', 'path-to-your-yaml-file', properties);


Example code is provided in the examples folder.


You can run npm test or npm run test:cover to run all tests and get a coverage report.


When you find issues, please report them:

Be sure to include all of the output from the npm command that didn't work as expected. The npm-debug.log file is also helpful to provide.


In lieu of a formal style guide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code.