roastr-container

A small dependency injection container for node and browsers.

Installation

npm install --save roastr-container

Getting Started

Most of the interaction with the container is through the set(), factory(), and get() methods.

In project/src/container.js

const Container = require('roastr-container');
let container   = new Container();

// Saves a static value in the container using the key 'config'.
container.set('config', {
    disablePoweredBy: true,
    port: 3000
});

// Saves a factory in the container using the key 'express'.
// Unlike the set() method, this method takes a function which will
// be called by the container to create the service. The function
// isn't called until the service is requested, and it's only called
// once. The value returned by the factory will then be cached in the
// container.
container.factory('express', function() {
    let express = require('express')();
    let config  = container.get('config');
    if (config.disablePoweredBy) {
        express.disable('x-powered-by');
    }
    
    return express;
});

// Saves a factory in the container using the key 'server'.
// Note these factory methods get values out of the container to
// construct themselves.
container.factory('server', function() {
    let express = container.get('express');
    return require('http').Server(express);
});

module.exports = container;

In project/src/bootstrap.js

const container = require('./container');

// Now the container is wired-up, and we can use the values in our
// application.
let config = container.get('config');
let server = container.get('server');
server.listen(config.port, function() {
    console.log('Listening on port ' + config.port);
});

Tagging Services

You may adds tags when saving a service in the container, and then retrieve services from the container by tag.

const Container = require('roastr-container');
let container   = new Container();

// The second argument here is a list of tags to be applied to the
// service. The second argument may be an array or string.
container.factory('body_parser', ['express.middleware'], function() {
    return require('body-parser').urlencoded({ extended: true })
});

container.factory('body_parser_json', ['express.middleware'], function() {
    return require('body-parser').json()
});

// Now we iterate over each service which has been tagged with
// express.middleware, and add the service to express.
container.factory('express', function() {
    let express = require('express')();
    container.tagged('express.middleware', function(middleware) {
        express.use(middleware);
    });
    
    return express;
});

Expanding Properties

Objects stored in the container may be automatically expanded using by container get() method using dot notation.

const Container = require('roastr-container');
let container   = new Container();

container.set('config', {
    disablePoweredBy: true,
    port: 3000
});

// We can do this.
let config = container.get('config');
let port = config.port;

// Or we can do this.
let port = container.get('config.port');

License

This project uses the MIT license. See LICENSE for more details.