Stable Interface
What it does
Configures the Injector
to return a value of another useExisting
token.
How to use
const provider: ExistingProvider = {provide: 'someToken', useExisting: 'someOtherToken'};
Interface Overview
interface ExistingProvider { provide : any useExisting : any multi : boolean }
Interface Description
For more details, see the Dependency Injection Guide.
Example
class Greeting { salutation = 'Hello'; } class FormalGreeting extends Greeting { salutation = 'Greetings'; } const injector = ReflectiveInjector.resolveAndCreate( [FormalGreeting, {provide: Greeting, useExisting: FormalGreeting}]); expect(injector.get(Greeting).salutation).toEqual('Greetings'); expect(injector.get(FormalGreeting).salutation).toEqual('Greetings'); expect(injector.get(FormalGreeting)).toBe(injector.get(Greeting));
Interface Details
provide : any
An injection token. (Typically an instance of Type
or OpaqueToken
, but can be any
).
useExisting : any
Existing token
to return. (equivalent to injector.get(useExisting)
)
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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