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ClassProvider

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

Configures the Injector to return an instance of useClass for a token.

Interface Overview

      
      interface ClassProvider { 
  provide: any
  useClass: Type<any>
  multi?: boolean
}

How To Use

      
      @Injectable()
class MyService {}

const provider: ClassProvider = {provide: 'someToken', useClass: MyService};

Description

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

Example

      
      abstract class Shape { name: string; }

class Square extends Shape {
  name = 'square';
}

const injector = ReflectiveInjector.resolveAndCreate([{provide: Shape, useClass: Square}]);

const shape: Shape = injector.get(Shape);
expect(shape.name).toEqual('square');
expect(shape instanceof Square).toBe(true);

Note that following two providers are not equal: 

      
      class Greeting {
  salutation = 'Hello';
}

class FormalGreeting extends Greeting {
  salutation = 'Greetings';
}

const injector = ReflectiveInjector.resolveAndCreate(
    [FormalGreeting, {provide: Greeting, useClass: FormalGreeting}]);

// The injector returns different instances.
// See: {provide: ?, useExisting: ?} if you want the same instance.
expect(injector.get(FormalGreeting)).not.toBe(injector.get(Greeting));

Members

      
      provide: any

An injection token. (Typically an instance of Type or InjectionToken, but can be any).

      
      useClass: Type<any>

Class to instantiate for the token.

      
      multi?: boolean

If true, then injector returns an array of instances. This is useful to allow multiple providers spread across many files to provide configuration information to a common token.

Example

      
      const locale = new InjectionToken<string[]>('locale');
const injector = Injector.create([
  {provide: locale, multi: true, useValue: 'en'},
  {provide: locale, multi: true, useValue: 'sk'},
]);

const locales: string[] = injector.get(locale);
expect(locales).toEqual(['en', 'sk']);