@mediaclip/dependency-injection

Dependency injection

A library for a simple strongly typed dependency injection.

It supports Singleton and Scoped registrations and guarantee at compile time that everything as been registered.

Example

Simple example with singletons only. You need to create a token to register a service in the container, and then you can use this token to resolve the service. You can register a service with it's instance directly or with a factory. The first parameter of the factory is the IDiContainer so you can use this to resolve other services if you have a service depending on naother one.

import {DiContainer, DiToken} from "@mediaclip/dependency-injection";

interface IService1 {}
class Service1 implements IService1 {}
interface IService2 {}
class Service2 implements IService2 {}
interface IService3 {}
class Service3 implements IService3 {
    constructor(
        private readonly service1: IService1,
        private readonly service2: IService2
    ) {
    }
}

let tokenService1 = DiToken.create<IService1>('Service1')
let tokenService2 = DiToken.create<IService2>('Service2')
let tokenService3 = DiToken.create<IService3>('Service3')

let container = new DiContainer();
container.registerSingleton(tokenService1, new Service1());
container.registerSingleton(tokenService2, new Service2());
container.registerSingleton(tokenService3, c => new Service3(
    c.resolve(tokenService1),
    c.resolve(tokenService2)
));

const service3 = container.resolve(tokenService3)

Scoped vs Singleton

When registering a service on the container you can either register it as singleton or as scoped. A singleton service will only be instantiated once, and a scoped service will have one instance of each scope. A scope is created by calling container.createScope()

Example: See sample

Module patterns

To avoid having a big file with the configuration of all the DI, it's preferable to split this into multiple files, kind of 1 module / folder or per things that go together.

Example: See sample