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@angular/corecode
FactoryProvider
interface
stable
Configures the Injector to return a value by invoking a useFactory function.
On this page
API
interface FactoryProvider extends FactorySansProvider { provide: any; multi?: boolean | undefined; override useFactory: Function; override deps?: any[] | undefined;}
multi
boolean | undefinedWhen true, 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.
useFactory
FunctionA function to invoke to create a value for this token. The function is invoked with
resolved values of tokens in the deps field.
deps
any[] | undefinedA list of tokens to be resolved by the injector. The list of values is then
used as arguments to the useFactory function.
Usage Notes
const Location = new InjectionToken('location');
const Hash = new InjectionToken('hash');
const injector = Injector.create({
providers: [
{provide: Location, useValue: 'https://angular.io/#someLocation'},
{
provide: Hash,
useFactory: (location: string) => location.split('#')[1],
deps: [Location],
},
],
});
expect(injector.get(Hash)).toEqual('someLocation');Dependencies can also be marked as optional:
const Location = new InjectionToken('location');
const Hash = new InjectionToken('hash');
const injector = Injector.create({
providers: [
{
provide: Hash,
useFactory: (location: string) => `Hash for: ${location}`,
// use a nested array to define metadata for dependencies.
deps: [[new Optional(), Location]],
},
],
});
expect(injector.get(Hash)).toEqual('Hash for: null');Multi-value example
const locale = new InjectionToken<string[]>('locale');
const injector = Injector.create({
providers: [
{provide: locale, multi: true, useValue: 'en'},
{provide: locale, multi: true, useValue: 'sk'},
],
});
const locales: string[] = injector.get(locale);
expect(locales).toEqual(['en', 'sk']);Jump to details