This is the archived documentation for Angular v5. Please visit angular.io to see documentation for the current version of Angular.

Injector

npm Package @angular/core
Module import { Injector } from '@angular/core';
Source core/src/di/injector.ts

Injector interface

Overview

      
      class Injector {
  static THROW_IF_NOT_FOUND: _THROW_IF_NOT_FOUND
  static NULL: Injector
  static create(options: StaticProvider[] | {...}, parent?: Injector): Injector
  get<T>(token: Type<T> | InjectionToken<T>, notFoundValue?: T): T
}

How To Use

      
      const injector: Injector = ...;
injector.get(...);

Description

For more details, see the "Dependency Injection Guide".

Example

      
      const injector: Injector =
    ReflectiveInjector.resolveAndCreate([{provide: 'validToken', useValue: 'Value'}]);
expect(injector.get('validToken')).toEqual('Value');
expect(() => injector.get('invalidToken')).toThrowError();
expect(injector.get('invalidToken', 'notFound')).toEqual('notFound');

Injector returns itself when given Injector as a token: 

      
      const injector = ReflectiveInjector.resolveAndCreate([]);
expect(injector.get(Injector)).toBe(injector);

Subclasses

Static Members

      
      static THROW_IF_NOT_FOUND: _THROW_IF_NOT_FOUND
    
      
      static NULL: Injector
    
      
      static create(options: StaticProvider[] | {
    providers: StaticProvider[];
    parent?: Injector;
    name?: string;
}, parent?: Injector): Injector

Create a new Injector which is configure using StaticProviders.

Example

      
      class Square {
  name = 'square';
}

const injector = Injector.create({providers: [{provide: Square, deps: []}]});

const shape: Square = injector.get(Square);
expect(shape.name).toEqual('square');
expect(shape instanceof Square).toBe(true);
Overloads 
      
      static create(providers: StaticProvider[], parent?: Injector): Injector
    
      
      static create(options: {
    providers: StaticProvider[];
    parent?: Injector;
    name?: string;
}): Injector

Members

      
      get<T>(token: Type<T> | InjectionToken<T>, notFoundValue?: T): T

Retrieves an instance from the injector based on the provided token. If not found:

  • Throws an error if no notFoundValue that is not equal to Injector.THROW_IF_NOT_FOUND is given
  • Returns the notFoundValue otherwise
Overloads 
      
      get(token: any, notFoundValue?: any): any