fl-node-di

Hierarchical NodeJS dependency injection inspired by Angular

See this library in action with this stackblitz demo.

Installation

Add the package to your project

npm i --save fl-node-di
# or
yarn add fl-node-di

Import the decorators with

import { FlModule, Component, Injectable, Inject } from 'fl-node-di'

Usage

NodeJS dependency injection module on top of inversify for using backend DI in a way similar to Angulars DI. E.g. you can use the following snippet throughout your complete application

@FlModule({
  imports: [ AuthModule, Http2Module ],
  declarations: [ AppComponent ],
  providers: [ AuthService ],
  exports: [ ]
})
export class AppModule {}

The other two decorators are

@Component()
export class AppComponent {
  constructor (@Inject(AuthService) authService: AuthService) {}
}

which treats the decorator as an inversify @injectable and directly creates an instance when the parent module gets instanciated. The other one is the @Injectable() decorator

@Injectable()
export class AuthService {}

which returns an inversify @injectable decorator, but does not directly creates an instance but instanciates itself when an @Inject(serviceIdentifier) is used as a constructor parameter in the same or a childs containers class.

The DI system is hierarchical.

Cheatsheet

The decorators:

Decorator	Description	Parameters	Return value
@FlModule()	Creates a container where the classes are stored, imports child-FlModules	config: { imports?: any[], declarations?: any[], providers?: any[], exports?: any[] }	Returns a custom decorator where a container object is created in the constructor
@Injectable()	Make class bindable to an FlModules container	-	Inversify @injectable()
@Component()	Make class bindable to an FlModules container	-	Inversify @injectable()
@Inject(serviceIdentifier)	Let the DI know that a class instance is needed, if not exist, create class	serviceIdentifier	-

The @FlModule() parameters:

Input parameter	Description
imports	Creates an instance of the imported FlModule(), reads the exports parameter of the instantiated object and stores the exports in its own container. The instance is handled as a child of this module, so Inject()s will work in the child even if the child does not contain the instance itself, but its parent.
declarations	Binds @Component() decorated classes to the container and after creating all imports it directly creates an instance.
providers	Binds @Injectable() decorated classes to the container
exports	Binds @Injectable() or @Component() decorated classes to the parents container

Dependencies

• inversify
• reflect-metadata