Is it possible to get the below behaviour with InversifyJS:
constructor(IDependency resolvedDependency, string myLiteral)
^ ^
Automatically resolve Defined Literal
If so, what's the best way to go about it?
There are a few things that you can do. Here I will post a few of them...
Injecting the literal as a constant value
let TYPES = {
IWarrior: Symbol("IWarrior"),
IWeapon: Symbol("IWeapon"),
rank: Symbol("rank")
}
interface IWeapon {}
@injectable()
class Katana implements IWeapon {}
interface IWarrior {
weapon: IWeapon;
rank: string;
}
@injectable()
class Warrior implements IWarrior {
public weapon: IWeapon;
public rank: string;
public constructor(
@inject(TYPES.IWeapon) weapon: IWeapon,
@inject(TYPES.rank) rank: string
) {
this.weapon = weapon;
this.rank = rank;
}
}
let kernel = new Kernel();
kernel.bind<IWarrior>(TYPES.IWarrior).to(Warrior);
kernel.bind<IWeapon>(TYPES.IWeapon).to(Katana);
kernel.bind<string>(TYPES.rank).toConstantValue("master");
Injecting the literal based on the context
Using contextual constraints you could inject a constant value for a particular context:
let kernel = new Kernel();
kernel.bind<IWarrior>(TYPES.IWarrior).to(Warrior);
kernel.bind<IWeapon>(TYPES.IWeapon).to(Katana);
kernel.bind<string>(TYPES.rank)
.toConstantValue("master")
.whenTargetTagged("rank", "master");
kernel.bind<string>(TYPES.rank)
.toConstantValue("student")
.whenTargetTagged("rank", "student");
let master = kernel.getTagged(TYPES.IWarrior, "rank", "master");
let student = kernel.getTagged(TYPES.IWarrior, "rank", "student");
injecting a factory
let TYPES = {
IWarrior: Symbol("IWarrior"),
IWeapon: Symbol("IWeapon"),
IFactoryOfIWarrior: Symbol("IFactory<IWarrior>")
}
interface IWeapon {}
@injectable()
class Katana implements IWeapon {}
interface IWarrior {
weapon: IWeapon;
rank: string;
}
@injectable()
class Warrior implements IWarrior {
public weapon: IWeapon;
public rank: string;
public constructor(
@inject(TYPES.IWeapon) weapon: IWeapon
) {
this.weapon = weapon;
this.rank = null; // important!
}
}
let kernel = new Kernel();
kernel.bind<IWarrior>(TYPES.IWarrior).to(Warrior);
kernel.bind<IWeapon>(TYPES.IWeapon).to(Katana);
kernel.bind<inversify.IFactory<IWarrior>>(TYPES.IFactoryOfIWarrior)
.toFactory<IWarrior>((context) => {
return (rank: string) => {
let warrior = context.kernel.get<IWarrior>(TYPES.IWarrior);
warrior.rank = rank;
return warrior;
};
});
let warriorFactory = kernel.get<inversify.IFactory<IWarrior>>(TYPES.IFactoryOfIWarrior);
let master = warriorFactory("master");
let student = warriorFactory("student");
You can inject factories into other classes:
@injectable()
class Army {
private _warriorFactory: (rank: string) => IWarrior;
private _soldiers: IWarrior[];
public constructor(
@inject(TYPES.IFactoryOfIWarrior) warriorFactory: (rank: string) => IWarrior
) {
this._warriorFactory = warriorFactory;
this._soldiers = [];
}
public newRecruit(rank: string) {
this._soldiers.push(this._warriorFactory(rank));
}
}
I think that the best solution is to use a factory.