node-dependency-injector

###A small and smart Dependency injection package for node.js without external dependencie, inspired by the powerful Symfony DI container.

Why nDI?

One of the reasons to use a DI Container is to organize your code in better way. Most Node.js projects use a lot of dependencies. Changes in dependencies often require a change in many files. Dependency management can help here to get an overview and to exchange components quickly.

With nDI you get a tool that helps you to better manage your external modules. Especially for larger projects that are bigger than a HelloWorld-Example, a Dependency Injection Container is essential for the maintainability of your project.

How to install nDI?

npm install  // for development

or

npm install node-dependency-injector  // for useage in your project

easy!

By the way, the code is 100% tested. try it!

npm test

The easiest way to integrate nDI is to use in the container and hand over your objects. You get a di module that you can instantiate.

const di = require('node-dependency-injector').getDic();

let MyDIC = new di();

or require a shared instance of the nDI if you use it in multiple files

let MyDIC = require('node-dependency-injector');

Here you can register your objects.

let myResource = { someProp: 'someData'};
MyDIC.set('myNamedResource', myResource);

at another place in the code you can use:

let myIncredibleObject = MyDIC.get('myNamedResource');

// do something meaningful with your Object
console.log(myIncredibleObject.someProp);

This is nothing exciting and can be realized with normal variable declarations.

Wait, it will be more exciting!

You can test an existing resource with:

let myConfig = { path: './someData/'};
MyDIC.set('config', myConfig);

if (MyDIC.has('config')) {
 ... do something
}

Here we go! The factory!

const animal = class Animal{ 
    constructor(){}
    bark(){ return 'GRRRRRR'; }
};

MyDIC.set('myAnimal', new animal());

... in the depths of the code ...

Get a Instance from your Resource

let Fiffi = MyDIC.get('myAnimal');

console.log(Fiffi.bark());

More advanced code usage

for example you have a class file

// animal.js
class Animal {
    constructor(name){
        this.name = name ;
     }

     getName(){
        return this.name;
     }
}

module.exports = Animal;

you can use a config variable or configFile

let serviceConfig = {
       autoload: true,
       parameters: {
           'animal.name': 'Kitty'
       },
       services : {
           'animal': {
               fileName: __dirname + '/animal',
               args: ['%animal.name%'],
               shared: true
           }
       }
   };

set it to nDI via setConfig

MyDIC.setConfig(serviceConfig);

and get your Class Instance from the DI

let MyCat = MyDIC.get('@animal');
console.log(MyCat.getName()); // => Kitty

configfile autoloader

Summary:

MyDIC.set('name', data) inserts a resource 

MyDIC.get('name') will return a resource

MyDIC.has('...') will return a boolean, true if a resource is present

MyDIC.setConfig({...}); will set your config, don't forget the autoloader!

MyDIC.get('@resourceName') will instantiate your resource from a config or configFile

and what is next?

• Fileloader integration for configfiles
• maybe yaml support