inversify-inject-decorators

inversify-inject-decorators

Lazy evaluated property injection decorators.

Motivation

Some frameworks and libraries take control over the creation of instances of a given class. For example, React takes control over the creation of instances of a given React component. This kind of frameworks and libraries prevent us from being able to use constructor injection and as a result they are not easy to integrate with InversifyJS.

InversifyJS also provides support for property injection but it also requires the instances of a class to be created by InversifyJS.

The decorators included in this library will allow you to lazy-inject properties even when the instances of a class cannot created by InversifyJS.

This library allows you tointegrate InversifyJS with any library or framework that takes control over the creation of instances of a given class.

Installation

You can install inversify-inject-decorators using npm:

$ npm install inversify inversify-inject-decorators reflect-metadata --save

The inversify-inject-decorators type definitions are included in the npm module and require TypeScript 2.0. Please refer to the InversifyJS documentation to learn more about the installation process.

Basic property lazy-injection with @lazyInject

The following example showcases how to inject into a property using the @lazyInject decorator:

import getDecorators from "inversify-inject-decorators";
import { Kernel, injectable, tagged, named } from "inversify";

let kernel = new Kernel();
let { lazyInject } = getDecorators(kernel);
let TYPES = { Weapon: "Weapon" };

interface Weapon {
    name: string;
    durability: number;
    use(): void;
}

@injectable()
class Sword implements Weapon {
    public name: string;
    public durability: number;
    public constructor() {
        this.durability = 100;
        this.name = "Sword";
    }
    public use() {
        this.durability = this.durability - 10;
    }
}

class Warrior {
    @lazyInject(TYPES.Weapon)
    public weapon: Weapon;
}

kernel.bind<Weapon>(TYPES.Weapon).to(Sword);

let warrior = new Warrior();
console.log(warrior.weapon instanceof Sword); // true

Named property injection with @lazyInjectNamed

The following example showcases how to inject into a named property using the @lazyInjectNamed decorator:

import getDecorators from "inversify-inject-decorators";
import { Kernel, injectable, named } from "inversify";

let kernel = new Kernel();
let { lazyInjectNamed } = getDecorators(kernel);
let TYPES = { Weapon: "Weapon" };

interface Weapon {
    name: string;
    durability: number;
    use(): void;
}

@injectable()
class Sword implements Weapon {
    public name: string;
    public durability: number;
    public constructor() {
        this.durability = 100;
        this.name = "Sword";
    }
    public use() {
        this.durability = this.durability - 10;
    }
}

@injectable()
class Shuriken implements Weapon {
    public name: string;
    public durability: number;
    public constructor() {
        this.durability = 100;
        this.name = "Shuriken";
    }
    public use() {
        this.durability = this.durability - 10;
    }
}

class Warrior {

    @lazyInjectNamed(TYPES.Weapon, "not-throwwable")
    @named("not-throwwable")
    public primaryWeapon: Weapon;

    @lazyInjectNamed(TYPES.Weapon, "throwwable")
    @named("throwwable")
    public secondaryWeapon: Weapon;

}

kernel.bind<Weapon>(TYPES.Weapon).to(Sword).whenTargetNamed("not-throwwable");
kernel.bind<Weapon>(TYPES.Weapon).to(Shuriken).whenTargetNamed("throwwable");

let warrior = new Warrior();
console.log(warrior.primaryWeapon instanceof Sword); // true
console.log(warrior.primaryWeapon instanceof Shuriken); // true

Tagged property injection with @lazyInjectTagged

The following example showcases how to inject a tagged property using the @lazyInjectTagged decorator:

import getDecorators from "inversify-inject-decorators";
import { Kernel, injectable, tagged } from "inversify";

let kernel = new Kernel();
let { lazyInjectTagged } = getDecorators(kernel);
let TYPES = { Weapon: "Weapon" };

interface Weapon {
    name: string;
    durability: number;
    use(): void;
}

@injectable()
class Sword implements Weapon {
    public name: string;
    public durability: number;
    public constructor() {
        this.durability = 100;
        this.name = "Sword";
    }
    public use() {
        this.durability = this.durability - 10;
    }
}

@injectable()
class Shuriken implements Weapon {
    public name: string;
    public durability: number;
    public constructor() {
        this.durability = 100;
        this.name = "Shuriken";
    }
    public use() {
        this.durability = this.durability - 10;
    }
}

class Warrior {

    @lazyInjectTagged(TYPES.Weapon, "throwwable", false)
    @tagged("throwwable", false)
    public primaryWeapon: Weapon;

    @lazyInjectTagged(TYPES.Weapon, "throwwable", true)
    @tagged("throwwable", true)
    public secondaryWeapon: Weapon;

}

kernel.bind<Weapon>(TYPES.Weapon).to(Sword).whenTargetTagged("throwwable", false);
kernel.bind<Weapon>(TYPES.Weapon).to(Shuriken).whenTargetTagged("throwwable", true);

let warrior = new Warrior();
console.log(warrior.primaryWeapon instanceof Sword); // true
console.log(warrior.primaryWeapon instanceof Shuriken); // true

Multi-injection into a property with @lazyMultiInject

The following example showcases how to multi-inject a property using the @lazyMultiInject decorator:

import getDecorators from "inversify-inject-decorators";
import { Kernel, injectable } from "inversify";

let kernel = new Kernel();
let { lazyMultiInject } = getDecorators(kernel);
let TYPES = { Weapon: "Weapon" };

interface Weapon {
    name: string;
    durability: number;
    use(): void;
}

@injectable()
class Sword implements Weapon {
    public name: string;
    public durability: number;
    public constructor() {
        this.durability = 100;
        this.name = "Sword";
    }
    public use() {
        this.durability = this.durability - 10;
    }
}

@injectable()
class Shuriken implements Weapon {
    public name: string;
    public durability: number;
    public constructor() {
        this.durability = 100;
        this.name = "Shuriken";
    }
    public use() {
        this.durability = this.durability - 10;
    }
}

class Warrior {

    @lazyMultiInject(TYPES.Weapon)
    public weapons: Weapon[];

}

kernel.bind<Weapon>(TYPES.Weapon).to(Sword);
kernel.bind<Weapon>(TYPES.Weapon).to(Shuriken);

let warrior = new Warrior();
console.log(warrior.weapons[0] instanceof Sword); // true
console.log(warrior.weapons[1] instanceof Shuriken); // true