Injector

Injector

class

Concrete injectors implement this interface. Injectors are configured with providers that associate dependencies of various types with injection tokens.

abstract class Injector {
  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
  abstract get<T>(token: ProviderToken<T>, notFoundValue?: T, flags?: InjectFlags): T
}

Subclasses

• ReflectiveInjector

See also

• "DI Providers".
• StaticProvider

Provided in

• 'any'

Static properties

Property	Description
static THROW_IF_NOT_FOUND: THROW_IF_NOT_FOUND
static NULL: Injector

Static methods

create()
static create(providers: StaticProvider[], parent?: Injector): Injector Deprecated from v5 use the new signature Injector.create(options) Parameters providers StaticProvider[] parent Injector Optional. Default is undefined. Returns Injector
Creates a new injector instance that provides one or more dependencies, according to a given type or types of StaticProvider. static create(options: { providers: StaticProvider[]; parent?: Injector; name?: string; }): Injector Parameters options object An object with the following properties: providers: An array of providers of the StaticProvider type. parent: (optional) A parent injector. name: (optional) A developer-defined identifying name for the new injector. Returns Injector: The new injector instance.

Methods

get()
Retrieves an instance from the injector based on the provided token.
abstract get<T>(token: ProviderToken<T>, notFoundValue?: T, flags?: InjectFlags): T Parameters token ProviderToken notFoundValue T Optional. Default is undefined. flags InjectFlags Optional. Default is undefined. Returns T: The instance from the injector if defined, otherwise the notFoundValue. Throws Error When the notFoundValue is undefined or Injector.THROW_IF_NOT_FOUND.
abstract get(token: any, notFoundValue?: any): any Deprecated from v4.0.0 use ProviderToken Parameters token any notFoundValue any Optional. Default is undefined. Returns any

Usage notes

The following example creates a service injector instance.

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);

Usage example

const injector: Injector =
    Injector.create({providers: [{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 = Injector.create({providers: []});
expect(injector.get(Injector)).toBe(injector);

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Licensed under the Creative Commons Attribution License 4.0.
https://angular.io/api/core/Injector-0