What it does
Configures the Injector to return a value by invoking a useFactory function.
How to use
function serviceFactory() { ... }
const provider: FactoryProvider = {provide: 'someToken', useFactory: serviceFactory, deps: []};
Interface Overview
interface FactoryProvider {
provide : any
useFactory : Function
deps : any[]
multi : boolean
}
Interface Description
For more details, see the Dependency Injection Guide.
Example
const Location = new OpaqueToken('location');
const Hash = new OpaqueToken('hash');
const injector = ReflectiveInjector.resolveAndCreate([
{provide: Location, useValue: 'http://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 OpaqueToken('location');
const Hash = new OpaqueToken('hash');
const injector = ReflectiveInjector.resolveAndCreate([{
provide: Hash,
useFactory: (location: string) => `Hash for: ${location}`,
// use a nested array to define metadata for dependencies.
deps: [[new Optional(), new Inject(Location)]]
}]);
expect(injector.get(Hash)).toEqual('Hash for: null');
Interface Details
provide : any
An injection token. (Typically an instance of Type or OpaqueToken, but can be any).
useFactory : Function
A 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[]
A list of tokens which need to be resolved by the injector. The list of values is than used as arguments to the useFactory function.
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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