express_utils

A library of commonly used express.js functions as created and used by the MRI Dev Team

Core Functions

RouteLoader

The routeLoader provides a directory based approach to registering API endpoints in an express application. To add additional endpoints simply add a new router file to your defined "routes" directory. Then the routeLoader will dynamically register all route files on application startup.

Usage:

const routeLoader = require('express_utils').routeLoader
    , ROUTEPREFIX = '/'  //this could be any url root you want your application's routes to be pathed behind
    ;

let app = express();

routeLoader.load(app, path.join(__dirname, 'app/routes'), ROUTEPREFIX);

the Routeloader will register all files in the supplied directory to a endpoint based on the name of the file itself. Take the following example:

// app/routes/test.js

'use strict';

let testRouter = require('express').Router()
  ;

module.exports = testRouter;

// /test route
testRouter.get('/', function(req, res, next) {
  res.status(200);
  res.end();
});

// /test/error route
testRouter.get('/error', function(req, res, next) {
  res.status(500);
  res.end();
})

With this example, uses the routeloader two endpoints would be created for the application:

/test /test/error

Remember the RouteLoader uses the Name of the file to create pathing. For a working example take a look at the unit test for the routeloader in this project.

bootExpressServer.js

The bootExpressServer provides a standard way to start express.js applications. It handles process termination events (SIGTERM/SIGINT) as well as normalizing of the provided port

Usage:

const bootExpressServer = require('express_utils).bootExpressServer'
    , PORT = process.env.PORT || 3000
    , TIMEOUT = 100000
    ;

var app = express();


// ... setup express app

bootExpressServer(app, PORT, TIMEOUT);

Middleware

Allow Cross Origin

Allow CORs middleware

var app = express=();
    , cors = require('express_utils').middleware.allowCrossOrigin
    ;


app.use(cors);

End Response

Uniform method for ending responses

var app = express()
  , endResponse = require('express_utils').middleware.endResponse
  ;


// ... setup express app, register routes, etc..

// anything that has fallen through here and has an error object passed to express "next()" function
app.all(endresponse);

Json Content Type

Sets the contentType header to 'application/json'

var app = express=();
    , json = require('express_utils').middleware.setJsonContentType
    ;


app.use(json);

Set Site Variables

Adds supplied object keys and values to req.app.locals for use throughout the app. This is useful for setting things like the application title or other globally defined variables. req.app.locals[key] = value will be set for each key supplied in the object.

var app = express=();
    , setSiteVariables = require('express_utils').middleware.setSiteVariables
    , siteVariables: {
        title: 'My App',
        description: 'application description'
        }
    ;


app.use(setSiteVariables(siteVariables);
// now req.app.locals.title && req.app.locals.description have been set and could be access in a jade view for example

ErrorWare

Error Handling

express_utils provides so generic error handling middleware functions to be re-used in most express.js applications.

404

Send 404 status for API calls

var app = express()
  , errorware = require('express_utils').middleware.error
  ;


// ... setup express app, register routes, etc..

// anything that has fallen through here is a 404
app.all('*', errorware[404]);

Render a 404 view for HTML calls

var app = express()
  , errorware = require('express_utils').middleware.error
   ;


// ... setup express app, register routes, etc..

// anything that has fallen through here is a 404
app.all('*', errorware['404Client']('my404ViewName');

404Client calls "res.render()"

500

Send 500 status for API calls

var app = express()
  , errorware = require('express_utils').middleware.error
  ;


// ... setup express app, register routes, etc..

// anything that has fallen through here and has an error object passed to express "next()" function
app.all('*', errorware[500]);

Render a 500 view for HTML calls

var app = express()
  , errorware = require('express_utils').middleware.error
   ;


// ... setup express app, register routes, etc..

// anything that has fallen through here is a 404
app.all('*', errorware['404Client']('my404ViewName');

Send Response with Error Message

Errorware to send the error message back

var app = express()
  , errorware = require('express_utils').middleware.error
  ;


// ... setup express app, register routes, etc..

// anything that has fallen through here and has an error object passed to express "next()" function
app.all('*', errorware[sendResponseWithErrorMessage]);

Set Error status code

Errorware to set the res.status to the error code or default to 500

var app = express()
  , errorware = require('express_utils').middleware.error
  ;


// ... setup express app, register routes, etc..

// anything that has fallen through here and has an error object passed to express "next()" function
app.all('*', errorware[setStatusCode]);