Init Decorator

Since Injex handles circular dependencies for you, one caveat is that you can't access injectable dependencies from module class constructors. Instead, you can use the @init() decorator to run module initialization upon creation.

Usage

You use the @init() decorator by decorating a module class method to behave as the initialize method. This method is called by the Injex runtime after all the modules created and instantiated.

import { define, init } from "@injex/core";

@define()

export class Zebra extends Animal {

@inject() private logger;

private _name: string;

constructor(name: string) {

this._name = name;

// `this.logger` and other injectables are not accessible

// from the constructor, so their value is `undefined`.

}

@init()

public initialize() {

// you can access injectables

this.logger.info(`Zebra ${this._name} created.`);

}

}

Inheritance

You can use multiple @init() methods when you inherit from a parent class, this way, you can benefit the auto-initialization in multiple classes.

For example:

import { define, init } from "@injex/core";

export abstract class Animal {

@inject() protected logger;

@init()

public initializeAnimal() {

this.logger.info('Animal created.');

}

}

@define()

export class Fox extends Animal {

@init()

public initializeFox() {

this.logger.info('Fox created.');

}

}

The initialization method invokes order is from the parent class to the inherited class, just like when you use a super() constructor.

Async/Await

Notice that you may return a promise from the initialization method if you like; Injex will "await" for it and return its promise from the factory method.

For example:

import { define, init, AsyncFactory } from "@injex/core";

@define()

export class Zebra extends Animal {

private _metadata: IAnimalMetadata;

@init()

public async initialize() {

this._metadata = await loadSomeData('zebra');

}

}

@define()

@singleton()

export class Zoo {

@inject(Zebra) zebraFactory: AsyncFactory<Zebra>;

private _animals: Animal[];

constructor() {

this._animals = [];

}

@init()

public async initialize() {

// zebra instance resolved when it's `@init()` method finishes loading

const zebra = await this.zebraFactory();

this._animals.push(

zebra

);

}

}