Stable Interface
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 { provide : any useClass : Type<any> multi : boolean }
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 OpaqueToken
, but can be any
).
useClass : Type<any>
Class to instantiate for the token
.
multi : boolean
If true, than 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 @angular/core/index, defined in @angular/core/src/di/provider.ts
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