Injector

Dependency injection for class injection and most of static decorator binding is resolved via injector.

export declare class Injector {

    static createAndResolveChild(
        parent: Injector, 
        Class: IProvider | Function, 
        providers: Array<IProvider | Function>
    ): Injector;

    static createAndResolve(
        Class: IProvider | Function, 
        providers: Array<IProvider | Function>
    ): Injector;

    constructor(parent?: Injector, keys?: Array<any>);

    createAndResolve(provider: IProvider, providers: Array<IProvider>): any;

    destroy(): void;

    has(key: any): boolean;

    get(provider: any, Class?: IProvider): any;

    set(key: any, value: Object): void;

    getId(): string;

}

Injector.createAndResolveChild

Static method which creates child injector on current injector and creates instance of Injectable class.

All providers token and token dependencies are automatically verified by static implementation.

Usage:

@Injectable()
class MyInjectableClass{
    @Inject("config")
    private config: Object;
}

let parent = new Injector();
let injector = Injector.createAndResolveChild(
  parent,
  MyInjectableClass,
  [
     {provide: "config", useValue: {id: 1, message: "This is custom provider for injector"}}
  ]
);
let myInstance = injector.get(MyInjectableClass);

Injector.createAndResolve

Static method which creates injector and instance of Injectable class.

All providers token and token dependencies are automatically verified by static implementation.

Usage:

@Injectable()
class MyInjectableClass{
    @Inject("config")
    private config: Object;
}

let injector = Injector.createAndResolve(
  MyInjectableClass,
  [
     {provide: "config", useValue: {id: 1, message: "This is custom provider for injector"}}
  ]
);
let myInstance = injector.get(MyInjectableClass);

constructor

Injector constructor

Usage:

// instance no parent injector and no mutable keys
let injector: Injector = new Injector();
injector.set('serviceA', 'valueA'); // serviceA
injector.set('serviceA', 'valueA1'); // throws exception you cannot reset value if is not set as mutable value

// instance no parent injector and mutable keys
let injector: Injector = new Injector(null, ['serviceA']);
injector.set('serviceA', 'valueA'); // injector sets serviceA to valueA
injector.set('serviceA', 'valueA1'); // injector sets serviceA to valueA1 no exception is thrown
// since serviceA is declared as mutable


// injector instance with parent injector and no mutable keys
let parent: Injector = new Injector();
parent.set('serviceA', 'valueA');
parent.set('serviceB', 'valueB');

let injector: Injector = new Injector(parent);
injector.set('serviceB', 'valueB1');

injector.get('serviceA'); // returns valueA
injector.get('serviceB'); // returns valueB1

createAndResolve

non static version of createAndResolve works only with verified providers

Usage:

@Injectable()
class MyTokenB {

}

@Injectable()
class MyTokenA {

    @Inject(MyTokenB)
    private token: MyTokenB;

    getToken() {
      return this.token;
    }

}

let injector: Injector = new Injector();

injector.createAndResolve(
    Metadata.verifyProvider(MyTokenA),
    Metadata.verifyProviders([
        {
            provide: MyTokenB,
            useClass: MyTokenB
        }
    ])
);


let tokenA1Init = injector.get(MyTokenA);

tokenA1Init.getToken(); // returns MyTokenB instance

destroy

destroy injector and all tokens and its child injector instances this method is mainly used by framework internally

let injector: Injector = new Injector();

injector.set('serviceA', 'valueA'); // serviceA
injector.set('serviceB', 'valueA'); // serviceB

injector.destory();

has

check if has defined provider in injector instance

let injector: Injector = new Injector();

injector.set('serviceA', 'valueA'); // serviceA
injector.set('serviceB', 'valueA'); // serviceB

injector.has('serviceA'); // true
injector.has('serviceB'); // true

set

this method is used internally by createAndResolve if you are not sure how injector works it's better to not use this method

class A {

}

let injector: Injector = new Injector();

injector.set('serviceA', new A); // serviceA

get

gets value by token

let injector: Injector = new Injector();

injector.set('serviceA', 'valueA'); // serviceA
injector.set('serviceB', 'valueA1'); // serviceB

injector.get('serviceA'); // valueA
injector.get('serviceB'); // valueA1

getId

get unique uuid generated on Injector init process, this is used only for debugging purposes

let injector: Injector = new Injector();

injector.getId(); // ab132zbf-bb76-4477-917b-df5d37c5088d