What it does
Configures the Injector to return an instance of useClass for a token.
How to use
@Injectable()
class MyService {}
const provider: ClassProvider = {provide: 'someToken', useClass: MyService};
Interface Overview
interface ClassProvider {}
Interface 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));
Interface Details
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.
const injector = ReflectiveInjector.resolveAndCreate([
{provide: 'local', multi: true, useValue: 'en'},
{provide: 'local', multi: true, useValue: 'sk'},
]);
const locales: string[] = injector.get('local');
expect(locales).toEqual(['en', 'sk']);
exported from core/index,
defined in core/src/di/provider.ts