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docs(dependency-injection): add Dart version, tweak TS version 

closes #972
This commit is contained in:
Kathy Walrath 2016-03-03 22:50:42 -08:00
parent e17821492e
commit 10877bdbfc
33 changed files with 865 additions and 499 deletions
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16
public/docs/_examples/dependency-injection/dart/.analysis_options Normal file
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@ -0,0 +1,16 @@
# Supported lint rules and documentation: http://dart-lang.github.io/linter/lints/
linter:
rules:
- always_declare_return_types
- camel_case_types
- empty_constructor_bodies
- annotate_overrides
- avoid_init_to_null
- constant_identifier_names
- one_member_abstracts
- slash_for_doc_comments
- sort_constructors_first
- unnecessary_brace_in_string_interp
analyzer:
# strong-mode: true

42
public/docs/_examples/dependency-injection/dart/lib/app_component.dart
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@ -1,15 +1,14 @@
// #docplaster
// #docregion
// #docregion imports
import 'package:angular2/core.dart';
import 'app_config.dart';
import 'car/car_component.dart';
import 'heroes/heroes_component.dart';
import 'app_config.dart';
import 'logger_service.dart';
import 'user_service.dart';
//PENDING: check whether we intend to hide injector_component.dart & providers_component.dart; if so, change docregion name?
// #enddocregion imports
import 'injector_component.dart';
import 'providers_component.dart';
@ -24,26 +23,32 @@ import 'providers_component.dart';
<h2>User</h2>
<p id="user">
{{userInfo}}
<button (click)=\'nextUser()\'>Next User</button>
<button (click)="nextUser()">Next User</button>
<p>
<my-heroes id="authorized" *ngIf="isAuthorized"></my-heroes>
<my-heroes id="unauthorized" *ngIf="!isAuthorized"></my-heroes>
''',
directives: const [CarComponent, HeroesComponent, InjectorComponent, ProvidersComponent],
<my-heroes id="unauthorized" *ngIf="!isAuthorized"></my-heroes>''',
directives: const [
CarComponent,
HeroesComponent,
InjectorComponent,
ProvidersComponent
],
// #docregion providers
providers: const [Logger, UserService, const Provider(Config, useValue: CONFIG)]
providers: const [
Logger,
UserService,
const Provider(AppConfig, useValue: config1)]
// #enddocregion providers
)
)
class AppComponent {
UserService _userService;
String title;
final UserService _userService;
final String title;
//#docregion ctor
AppComponent(Config config, this._userService) {
title = config.title;
}
AppComponent(AppConfig config, this._userService)
: title = config.title;
// #enddocregion ctor
bool get isAuthorized {
return user.isAuthorized;
}
@ -56,8 +61,7 @@ class AppComponent {
return _userService.user;
}
String get userInfo {
return 'Current user, ${user.name}, is ${isAuthorized ? "" : "not"} authorized. ';
}
String get userInfo => 'Current user, ${user.name}, is'
'${isAuthorized ? "" : " not"} authorized. ';
}
// #enddocregion

6
public/docs/_examples/dependency-injection/dart/lib/app_component_1.dart
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@ -2,6 +2,7 @@
// #docregion
import 'package:angular2/core.dart';
import 'car/car_component.dart';
import 'heroes/heroes_component_1.dart';
@ -10,11 +11,10 @@ import 'heroes/heroes_component_1.dart';
template: '''
<h1>{{title}}</h1>
<my-car></my-car>
<my-heroes></my-heroes>
''',
<my-heroes></my-heroes>''',
directives: const [CarComponent, HeroesComponent])
class AppComponent {
var title = 'Dependency Injection';
final String title = 'Dependency Injection';
}
// #enddocregion

20
public/docs/_examples/dependency-injection/dart/lib/app_component_2.dart
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@ -2,34 +2,32 @@
// #docregion imports
import 'package:angular2/core.dart';
import 'app_config.dart';
import 'car/car_component.dart';
import 'heroes/heroes_component_1.dart';
import 'app_config.dart';
import 'logger_service.dart';
// #enddocregion imports
@Component(
selector: 'my-app',
template: '''
<h1>{{title}}</h1>
<my-car></my-car>
<my-heroes></my-heroes>
''',
<my-heroes></my-heroes>''',
directives: const [
CarComponent,
HeroesComponent
],
providers: const [
Logger,
// #docregion provider-config
const Provider('app.config', useValue: CONFIG)
const Provider(AppConfig, useValue: config1)
])
class AppComponent {
String title;
final String title;
// #docregion ctor
AppComponent(@Inject('app.config') Config config) {
title = config.title;
}
AppComponent(AppConfig config)
: title = config.title;
// #enddocregion
}
// #enddocregion

32
public/docs/_examples/dependency-injection/dart/lib/app_config.dart
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@ -1,29 +1,17 @@
//#docregion
// #docregion
// #docregion token
import 'package:angular2/core.dart';
const APP_CONFIG = const OpaqueToken('app.config');
// #enddocregion token
//#docregion config
abstract class Config {
final String apiEndpoint;
//#docregion const-class
@Injectable()
class AppConfig {
final apiEndpoint;
final String title;
const Config({this.apiEndpoint, this.title});
const AppConfig(this.apiEndpoint, this.title);
}
//#enddocregion const-class
class ConfigImpl implements Config {
final String apiEndpoint;
final String title;
const ConfigImpl({this.apiEndpoint, this.title});
}
const CONFIG = const ConfigImpl(apiEndpoint: 'api.heroes.com', title: 'Dependency Injection');
//#enddocregion config
//#docregion config-hash
const CONFIG_HASH = const {'apiEndpoint': 'api.heroes.com', 'title': 'Dependency Injection'};
//#enddocregion config-hash
//#docregion const-object
const config1 = const AppConfig('api.heroes.com', 'Dependency Injection');
//#enddocregion const-object

12
public/docs/_examples/dependency-injection/dart/lib/car/car.dart
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@ -1,13 +1,14 @@
// #docregion
import 'package:angular2/core.dart';
@Injectable()
// #docregion engine
class Engine {
int cylinders = 4;
final int cylinders = 4;
}
// #enddocregion engine
@Injectable()
// #docregion tires
class Tires {
String make = 'Flintstone';
@ -18,8 +19,8 @@ class Tires {
@Injectable()
class Car {
//#docregion car-ctor
Engine engine;
Tires tires;
final Engine engine;
final Tires tires;
String description = 'DI';
Car(this.engine, this.tires);
@ -27,6 +28,7 @@ class Car {
// #enddocregion car-ctor
// Method using the engine and tires
String drive() => '$description car with ${engine.cylinders} cylinders and ${tires.make} tires.';
String drive() => '$description car with ${engine.cylinders} cylinders'
' and ${tires.make} tires.';
}
// #enddocregion car

14
public/docs/_examples/dependency-injection/dart/lib/car/car_component.dart
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@ -1,11 +1,11 @@
// #docregion
import 'package:angular2/core.dart';
import 'car.dart';
import 'car_no_di.dart' as carNoDi;
import 'car_factory.dart';
import 'car_creations.dart' as carCreations;
import 'car_factory.dart';
import 'car_injector.dart';
import 'car_no_di.dart' as carNoDi;
@Component(
selector: 'my-car',
@ -17,13 +17,13 @@ import 'car_injector.dart';
<div id="factory">{{factoryCar.drive()}}</div>
<div id="simple">{{simpleCar.drive()}}</div>
<div id="super">{{superCar.drive()}}</div>
<div id="test">{{testCar.drive()}}</div>
''',
<div id="test">{{testCar.drive()}}</div>''',
providers: const [Car, Engine, Tires])
class CarComponent {
Car car;
final Car car;
CarComponent(this.car);
CarComponent(this.car) {}
Car factoryCar = (new CarFactory()).createCar();
Car injectorCar = useInjector();
carNoDi.Car noDiCar = new carNoDi.Car();

30
public/docs/_examples/dependency-injection/dart/lib/car/car_creations.dart
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@ -1,12 +1,10 @@
// Examples with car and engine variations
// #docplaster
// Examples with car and engine variations
import 'car.dart';
///////// example 1 ////////////
Car simpleCar() {
//#docregion car-ctor-instantiation
// Simple car with 4 cylinders and Flintstone tires.
var car = new Car(new Engine(), new Tires());
//#enddocregion car-ctor-instantiation
@ -17,19 +15,18 @@ Car simpleCar() {
//#docregion car-ctor-instantiation-with-param
class Engine2 implements Engine {
int cylinders;
final int cylinders;
Engine2(this.cylinders);
}
//#enddocregion car-ctor-instantiation-with-param
Car superCar() {
//#docregion car-ctor-instantiation-with-param
// Super car with 12 cylinders and Flintstone tires.
var bigCylinders = 12;
var car = new Car(new Engine2(bigCylinders), new Tires());
//#enddocregion car-ctor-instantiation-with-param
Car superCar() {
//#docregion car-ctor-instantiation-with-param
// Super car with 12 cylinders and Flintstone tires.
var bigCylinders = 12;
var car = new Car(new Engine2(bigCylinders), new Tires());
//#enddocregion car-ctor-instantiation-with-param
car.description = 'Super';
return car;
}
@ -37,7 +34,7 @@ Car superCar() {
//#docregion car-ctor-instantiation-with-mocks
class MockEngine extends Engine {
int cylinders = 8;
final int cylinders = 8;
}
class MockTires extends Tires {
@ -46,11 +43,10 @@ class MockTires extends Tires {
//#enddocregion car-ctor-instantiation-with-mocks
Car testCar() {
//#docregion car-ctor-instantiation-with-mocks
// Test car with 8 cylinders and YokoGoodStone tires.
var car = new Car(new MockEngine(), new MockTires());
//#enddocregion car-ctor-instantiation-with-mocks
//#docregion car-ctor-instantiation-with-mocks
// Test car with 8 cylinders and YokoGoodStone tires.
var car = new Car(new MockEngine(), new MockTires());
//#enddocregion car-ctor-instantiation-with-mocks
car.description = 'Test';
return car;
}

8
public/docs/_examples/dependency-injection/dart/lib/car/car_factory.dart
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@ -1,15 +1,13 @@
// #docregion
import 'car.dart';
// BAD pattern!
class CarFactory {
Car createCar() {
var car = new Car(createEngine(), createTires());
car.description = 'Factory';
return car;
return new Car(createEngine(), createTires())
..description = 'Factory';
}
Engine createEngine() => new Engine();
Tires createTires() => new Tires();
}

6
public/docs/_examples/dependency-injection/dart/lib/car/car_injector.dart
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@ -1,9 +1,9 @@
// #docplaster
//#docregion
import 'package:angular2/core.dart';
import 'car.dart';
import '../logger_service.dart';
import 'car.dart';
//#docregion injector
Car useInjector() {
@ -24,8 +24,8 @@ Car useInjector() {
//#docregion injector-call
var car = injector.get(Car);
//#enddocregion injector-call
//#enddocregion injector-create-and-call
car.description = 'Injector';
var logger = injector.get(Logger);
logger.log('Injector car.drive() said: ' + car.drive());

4
public/docs/_examples/dependency-injection/dart/lib/car/car_no_di.dart
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@ -13,10 +13,10 @@ class Car {
engine = new Engine();
tires = new Tires();
}
//#enddocregion car-ctor
// Method using the engine and tires
drive() => '$description car with ${engine.cylinders} cylinders and ${tires.make} tires.';
String drive() => '$description car with '
'${engine.cylinders} cylinders and ${tires.make} tires.';
}
//#enddocregion car

1
public/docs/_examples/dependency-injection/dart/lib/heroes/hero.dart
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@ -1,5 +1,4 @@
// #docregion
class Hero {
num id;
String name;

9
public/docs/_examples/dependency-injection/dart/lib/heroes/hero_list_component.dart
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@ -1,6 +1,6 @@
// #docregion
import 'package:angular2/core.dart';
import 'hero.dart';
import 'hero_service.dart';
@ -9,11 +9,10 @@ import 'hero_service.dart';
template: '''
<div *ngFor="#hero of heroes">
{{hero.id}} - {{hero.name}}
({{hero.isSecret ? \'secret\' : \'public\'}})
</div>
''')
({{hero.isSecret ? 'secret' : 'public'}})
</div>''')
class HeroListComponent {
List<Hero> heroes;
final List<Hero> heroes;
//#docregion ctor-signature
HeroListComponent(HeroService heroService) : heroes = heroService.getHeroes();

7
public/docs/_examples/dependency-injection/dart/lib/heroes/hero_list_component_1.dart
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@ -1,6 +1,6 @@
// #docregion
import 'package:angular2/core.dart';
import 'hero.dart';
import 'mock_heroes.dart';
@ -9,8 +9,7 @@ import 'mock_heroes.dart';
template: '''
<div *ngFor="#hero of heroes">
{{hero.id}} - {{hero.name}}
</div>
''')
</div>''')
class HeroListComponent {
List<Hero> heroes = HEROES;
final List<Hero> heroes = HEROES;
}

10
public/docs/_examples/dependency-injection/dart/lib/heroes/hero_list_component_2.dart
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@ -1,6 +1,6 @@
// #docregion
import 'package:angular2/core.dart';
import 'hero.dart';
import 'hero_service.dart';
@ -9,12 +9,12 @@ import 'hero_service.dart';
template: '''
<div *ngFor="#hero of heroes">
{{hero.id}} - {{hero.name}}
</div>
''')
</div>''')
class HeroListComponent {
List<Hero> heroes;
final List<Hero> heroes;
//#docregion ctor
HeroListComponent(HeroService heroService) : heroes = heroService.getHeroes();
HeroListComponent(HeroService heroService)
: heroes = heroService.getHeroes();
//#enddocregion ctor
}

14
public/docs/_examples/dependency-injection/dart/lib/heroes/hero_service.dart
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@ -1,22 +1,24 @@
// #docregion
import 'package:angular2/core.dart';
import '../logger_service.dart';
import 'hero.dart';
import 'mock_heroes.dart';
import '../logger_service.dart';
@Injectable()
class HeroService {
// #docregion internals
Logger _logger;
bool _isAuthorized;
final Logger _logger;
final bool _isAuthorized;
HeroService(this._logger, this._isAuthorized);
List<Hero> getHeroes() {
var auth = _isAuthorized ? 'authorized' : 'unauthorized';
_logger.log('Getting heroes for ${auth} user.');
return HEROES.where((hero) => _isAuthorized || !hero.isSecret).toList();
_logger.log('Getting heroes for $auth user.');
return HEROES
.where((hero) => _isAuthorized || !hero.isSecret)
.toList();
}
// #enddocregion internals
}

1
public/docs/_examples/dependency-injection/dart/lib/heroes/hero_service_1.dart
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@ -1,5 +1,4 @@
// #docregion
import 'hero.dart';
import 'mock_heroes.dart';

6
public/docs/_examples/dependency-injection/dart/lib/heroes/hero_service_2.dart
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@ -1,13 +1,13 @@
// #docregion
import 'package:angular2/core.dart';
import '../logger_service.dart';
import 'hero.dart';
import 'mock_heroes.dart';
import '../logger_service.dart';
@Injectable()
class HeroService {
Logger _logger;
final Logger _logger;
//#docregion ctor
HeroService(this._logger);

10
public/docs/_examples/dependency-injection/dart/lib/heroes/hero_service_provider.dart
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@ -1,16 +1,18 @@
// #docregion
import 'package:angular2/core.dart';
import 'hero_service.dart';
import '../logger_service.dart';
import '../user_service.dart';
import 'hero_service.dart';
// #docregion factory
@Injectable()
heroServiceFactory(Logger logger, UserService userService) =>
new HeroService(logger, userService.user.isAuthorized);
// #enddocregion factory
// #docregion provider
const heroServiceProvider =
const Provider(HeroService, useFactory: heroServiceFactory, deps: const [Logger, UserService]);
const heroServiceProvider = const Provider(HeroService,
useFactory: heroServiceFactory,
deps: const [Logger, UserService]);
// #enddocregion provider

5
public/docs/_examples/dependency-injection/dart/lib/heroes/heroes_component.dart
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@ -1,6 +1,6 @@
// #docregion
import 'package:angular2/core.dart';
import 'hero_list_component.dart';
import 'hero_service_provider.dart';
@ -8,8 +8,7 @@ import 'hero_service_provider.dart';
selector: 'my-heroes',
template: '''
<h2>Heroes</h2>
<hero-list></hero-list>
''',
<hero-list></hero-list>''',
providers: const [heroServiceProvider],
directives: const [HeroListComponent])
class HeroesComponent {}

8
public/docs/_examples/dependency-injection/dart/lib/heroes/heroes_component_1.dart
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@ -1,20 +1,18 @@
// #docplaster
// #docregion
// #docregion v1
import 'package:angular2/core.dart';
import 'hero_list_component.dart';
import 'hero_list_component.dart';
// #enddocregion v1
import 'hero_service.dart';
// #docregion v1
@Component(
selector: 'my-heroes',
template: '''
<h2>Heroes</h2>
<hero-list></hero-list>
''',
<hero-list></hero-list>''',
// #enddocregion v1
// #docregion providers
providers: const [HeroService],

1
public/docs/_examples/dependency-injection/dart/lib/heroes/mock_heroes.dart
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@ -1,5 +1,4 @@
// #docregion
import 'hero.dart';
List<Hero> HEROES = [

29
public/docs/_examples/dependency-injection/dart/lib/injector_component.dart
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@ -2,21 +2,21 @@
//#docregion
import 'package:angular2/core.dart';
import 'car/car.dart';
import 'heroes/hero.dart';
import 'heroes/hero_service.dart';
import 'heroes/hero_service_provider.dart';
import 'logger_service.dart';
import 'package:dependency_injection/heroes/hero.dart';
//#docregion injector
@Component(
selector: 'my-injectors',
template: '''
<h2>Other Injections</h2>
<div id="car"> {{car.drive()}}</div>
<div id="car">{{car.drive()}}</div>
<div id="hero">{{hero.name}}</div>
<div id="rodent">{{rodent}}</div>
''',
<div id="rodent">{{rodent}}</div>''',
providers: const [
Car,
Engine,
@ -25,20 +25,9 @@ import 'package:dependency_injection/heroes/hero.dart';
Logger
])
class InjectorComponent {
Injector _injector;
InjectorComponent(this._injector) {
car = _injector.get(Car);
heroService = _injector.get(HeroService);
hero = heroService.getHeroes()[0];
}
final Injector _injector;
Car car;
//#docregion get-hero-service
HeroService heroService;
//#enddocregion get-hero-service
Hero hero;
String get rodent {
@ -48,6 +37,14 @@ class InjectorComponent {
}
return "R.O.U.S.'s? I don't think they exist!";
}
InjectorComponent(this._injector) {
car = _injector.get(Car);
//#docregion get-hero-service
heroService = _injector.get(HeroService);
//#enddocregion get-hero-service
hero = heroService.getHeroes()[0];
}
}
//#enddocregion injector

1
public/docs/_examples/dependency-injection/dart/lib/logger_service.dart
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@ -1,5 +1,4 @@
// #docregion
import 'package:angular2/core.dart';
@Injectable()

304
public/docs/_examples/dependency-injection/dart/lib/providers_component.dart
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@ -2,22 +2,19 @@
//#docplaster
import 'package:angular2/core.dart';
import 'app_config.dart';
import 'heroes/hero_service_provider.dart';
import 'heroes/hero_service.dart';
import 'logger_service.dart';
import 'user_service.dart';
// #docregion import-optional
import 'package:angular2/core.dart' show Optional;
// #enddocregion import-optional
const template = '{{log}}';
//////////////////////////////////////////
@Component(selector: 'provider-1', template: '{{log}}', providers:
@Component(
selector: 'provider-1',
template: '{{log}}',
providers:
//#docregion providers-1
const [Logger]
const [Logger]
//#enddocregion providers-1
)
class ProviderComponent1 {
@ -25,14 +22,16 @@ class ProviderComponent1 {
ProviderComponent1(Logger logger) {
logger.log('Hello from logger provided with Logger class');
log = logger.logs[0];
log = logger.logs.last;
}
}
//////////////////////////////////////////
@Component(selector: 'provider-2', template: '{{log}}', providers:
@Component(
selector: 'provider-2',
template: '{{log}}',
providers:
//#docregion providers-2
const [const Provider(Logger, useClass: Logger)]
const [const Provider(Logger, useClass: Logger)]
//#enddocregion providers-2
)
class ProviderComponent2 {
@ -40,36 +39,32 @@ class ProviderComponent2 {
ProviderComponent2(Logger logger) {
logger.log('Hello from logger provided with Provider class and useClass');
log = logger.logs[0];
log = logger.logs.last;
}
}
//////////////////////////////////////////
@Component(
selector: 'provider-3',
template: '{{log}}',
providers: const [const Provider(Logger, useClass: Logger)]
/*
//#docregion providers-3
const [provide(Logger, useClass: Logger)]
//#enddocregion providers-3
*/
)
providers: const [const Provider(Logger, useClass: Logger)])
class ProviderComponent3 {
String log;
ProviderComponent3(Logger logger) {
logger.log('Hello from logger provided with useClass');
log = logger.logs[0];
log = logger.logs.last;
}
}
//////////////////////////////////////////
@Injectable()
class BetterLogger extends Logger {}
@Component(selector: 'provider-4', template: '{{log}}', providers:
@Component(
selector: 'provider-4',
template: '{{log}}',
providers:
//#docregion providers-4
const [const Provider(Logger, useClass: BetterLogger)]
const [const Provider(Logger, useClass: BetterLogger)]
//#enddocregion providers-4
)
class ProviderComponent4 {
@ -77,31 +72,32 @@ class ProviderComponent4 {
ProviderComponent4(Logger logger) {
logger.log('Hello from logger provided with useClass:BetterLogger');
log = logger.logs[0];
log = logger.logs.last;
}
}
//////////////////////////////////////////
// #docregion EvenBetterLogger
@Injectable()
class EvenBetterLogger implements Logger {
UserService _userService;
List<String> logs = [];
final UserService _userService;
@override List<String> logs = [];
EvenBetterLogger(this._userService);
log(String message) {
message = 'Message to ${ _userService.user.name}: ${ message}.';
print(message);
logs.add(message);
@override void log(String message) {
var msg = 'Message to ${_userService.user.name}: $message.';
print(msg);
logs.add(msg);
}
}
// #enddocregion EvenBetterLogger
@Component(selector: 'provider-5', template: '{{log}}', providers:
@Component(
selector: 'provider-5',
template: '{{log}}',
providers:
//#docregion providers-5
const [UserService, const Provider(Logger, useClass: EvenBetterLogger)]
const [UserService, const Provider(Logger, useClass: EvenBetterLogger)]
//#enddocregion providers-5
)
class ProviderComponent5 {
@ -109,29 +105,30 @@ class ProviderComponent5 {
ProviderComponent5(Logger logger) {
logger.log('Hello from EvenBetterlogger');
log = logger.logs[0];
log = logger.logs.last;
}
}
//////////////////////////////////////////
@Injectable()
class NewLogger extends Logger implements OldLogger {}
class OldLogger {
List<String> logs = [];
log(String message) {
void log(String message) {
throw new Exception('Should not call the old logger!');
}
}
@Component(selector: 'provider-6a', template: '{{log}}', providers:
//#docregion providers-6a
const [
NewLogger,
// Not aliased! Creates two instances of `NewLogger`
const Provider(OldLogger, useClass: NewLogger)
]
//#enddocregion providers-6a
@Component(
selector: 'provider-6a',
template: '{{log}}',
providers:
//#docregion providers-6a
const [NewLogger,
// Not aliased! Creates two instances of `NewLogger`
const Provider(OldLogger, useClass: NewLogger)]
//#enddocregion providers-6a
)
class ProviderComponent6a {
String log;
@ -144,18 +141,22 @@ class ProviderComponent6a {
// The newLogger wasn't called so no logs[]
// display the logs of the oldLogger.
log = newLogger.logs == null || newLogger.logs.isEmpty ? oldLogger.logs[0] : newLogger.logs[0];
log = newLogger.logs == null || newLogger.logs.isEmpty
? oldLogger.logs[0]
: newLogger.logs[0];
}
}
@Component(selector: 'provider-6b', template: '{{log}}', providers:
//#docregion providers-6b
const [
NewLogger,
// Alias OldLogger w/ reference to NewLogger
const Provider(OldLogger, useExisting: NewLogger)
//#enddocregion providers-6b
])
@Component(
selector: 'provider-6b',
template: '{{log}}',
providers:
//#docregion providers-6b
const [NewLogger,
// Alias OldLogger with reference to NewLogger
const Provider(OldLogger, useExisting: NewLogger)]
//#enddocregion providers-6b
)
class ProviderComponent6b {
String log;
@ -167,43 +168,46 @@ class ProviderComponent6b {
log = newLogger.logs[0];
}
}
//////////////////////////////////////////
// #docregion silent-logger
// #docregion opaque-token
const loggerPrefix = const OpaqueToken('Logger prefix');
// #enddocregion opaque-token
// An object in the shape of the logger service
class SilentLogger /*implements Logger*/ {
const SilentLogger({this.logs});
// #docregion configurable-logger
@Injectable()
class ConfigurableLogger extends Logger {
final String _prefix;
final List<String> logs;
// #docregion use-opaque-token
ConfigurableLogger(@Inject(loggerPrefix) this._prefix);
// #enddocregion use-opaque-token
log(String message) {}
@override
void log(String msg) {
super.log('$_prefix: $msg');
}
}
// #enddocregion configurable-logger
const silentLogger = const SilentLogger(
logs: const ['Silent logger says "Shhhhh!". Provided via "useValue"']);
// #enddocregion silent-logger
@Component(selector: 'provider-7', template: '{{log}}', providers:
@Component(selector: 'provider-7', template: '{{message}}',
//#docregion providers-7
const [const Provider(SilentLogger, useValue: silentLogger)]
providers: const [
const Provider(Logger, useClass: ConfigurableLogger),
//#docregion providers-usevalue
const Provider(loggerPrefix, useValue: 'Testing')
//#enddocregion providers-usevalue
]
//#enddocregion providers-7
/*
//#docregion providers-7-unchecked
const [const Provider(Logger, useValue: silentLogger)]
//#enddocregion providers-7-unchecked
*/
)
class ProviderComponent7 {
String log;
String message;
ProviderComponent7(SilentLogger logger) {
logger.log('Hello from logger provided with useValue');
log = logger.logs[0];
ProviderComponent7(Logger logger) {
logger.log('Hello from configurable logger.');
message = logger.logs.last;
}
}
/////////////////
@Component(selector: 'provider-8', template: '{{log}}', providers: const [
const Provider(HeroService, useFactory: heroServiceFactory),
Logger,
@ -219,111 +223,86 @@ class ProviderComponent8 {
var log = 'Hero service injected successfully';
}
/////////////////
@Component(selector: 'provider-9a', template: '{{log}}', providers:
/*
// #docregion providers-9a-interface
// WOKRKS! Can use abstract class as provider token
[provide(Config, {useValue: CONFIG})]
// #enddocregion providers-9a-interface
*/
// #docregion providers-9a
// Use string as provider token
const [const Provider('app.config', useValue: CONFIG_HASH)]
//#enddocregion providers-9a
@Component(
selector: 'provider-9',
template: '{{log}}',
providers:
// #docregion providers-9
const [const Provider(AppConfig, useValue: config1)]
// #enddocregion providers-9
)
class ProviderComponent9a implements OnInit {
Config _config;
class ProviderComponent9 implements OnInit {
AppConfig _config;
String log;
/*
// #docregion provider-9a-ctor-interface
// WORKS! Can inject using the abstract class as the parameter type
Config _config;
ProviderComponent9(AppConfig this._config);
ProviderComponent9a(this._config);
// #enddocregion provider-9a-ctor-interface
*/
// #docregion provider-9a-ctor
// @Inject(token) to inject the dependency
ProviderComponent9a(@Inject('app.config') Map config) {
_config = new ConfigImpl(apiEndpoint: config['apiEndpoint'], title: config['title']);
}
// #enddocregion provider-9a-ctor
ngOnInit() {
log = '\'app.config\' Application title is ' + _config.title;
@override
void ngOnInit() {
log = 'appConfigToken Application title is ${_config.title}';
}
}
@Component(selector: 'provider-9b', template: '{{log}}', providers:
// #docregion providers-9b
const [const Provider(APP_CONFIG, useValue: CONFIG_HASH)]) // #enddocregion providers-9b
class ProviderComponent9b
implements OnInit {
Config _config;
String log;
// #docregion provider-9b-ctor
ProviderComponent9b(@Inject(APP_CONFIG) Map config) {
_config = new ConfigImpl(apiEndpoint: config['apiEndpoint'], title: config['title']);
}
// #enddocregion provider-9b-ctor
ngOnInit() {
log = 'APP_CONFIG Application title is ' + _config.title;
}
}
//////////////////////////////////////////
// Normal required logger
@Component(selector: 'provider-10a', template: '{{log}}',
//#docregion providers-logger
providers: const [Logger]
//#enddocregion providers-logger
)
)
class ProviderComponent10a {
String log;
ProviderComponent10a(Logger logger) {
logger.log('Hello from the required logger.');
log = logger.logs[0];
log = logger.logs.last;
}
}
// Optional logger
// Optional logger, can be null
@Component(selector: 'provider-10b', template: '{{log}}')
class ProviderComponent10b implements OnInit {
Logger _logger;
class ProviderComponent10b {
// #docregion provider-10-ctor
final Logger _logger;
String log;
ProviderComponent10b(@Optional() this._logger);
ProviderComponent10b(@Optional() Logger this._logger) {
// . . .
// #enddocregion provider-10-ctor
ngOnInit() {
// #docregion provider-10-logger
// No logger? Make one!
if (_logger == null) {
_logger = new Logger();
// #enddocregion provider-10-logger
_logger.log('Optional logger was not available.');
} else {
_logger.log('Hello from the injected logger.');
log = _logger.logs[0];
}
log = _logger.logs[0];
_logger == null ? log = 'No logger exists' : log = _logger.logs.last;
// #docregion provider-10-ctor
}
// #enddocregion provider-10-ctor
}
/////////////////
// Optional logger, non null
@Component(selector: 'provider-10c', template: '{{log}}')
class ProviderComponent10c {
// #docregion provider-10-logger
final Logger _logger;
String log;
ProviderComponent10c(@Optional() Logger logger) :
_logger = logger ?? new DoNothingLogger() {
// . . .
// #enddocregion provider-10-logger
logger == null
? _logger.log('Optional logger was not available.')
: _logger.log('Hello from the injected logger.');
log = _logger.logs.last;
// #docregion provider-10-logger
}
// #enddocregion provider-10-logger
}
// #docregion provider-10-logger
// . . .
@Injectable()
class DoNothingLogger extends Logger {
@override List<String> logs = [];
@override void log(String msg) => logs.add(msg);
}
// #enddocregion provider-10-logger
@Component(
selector: 'my-providers',
template: '''
@ -337,11 +316,10 @@ class ProviderComponent10b implements OnInit {
<div id="p6b"><provider-6b></provider-6b></div>
<div id="p7"><provider-7></provider-7></div>
<div id="p8"><provider-8></provider-8></div>
<div id="p9a"><provider-9a></provider-9a></div>
<div id="p9b"><provider-9b></provider-9b></div>
<div id="p8"><provider-9></provider-9></div>
<div id="p10a"><provider-10a></provider-10a></div>
<div id="p10b"><provider-10b></provider-10b></div>
''',
<div id="p10c"><provider-10c></provider-10c></div>''',
directives: const [
ProviderComponent1,
ProviderComponent2,
@ -352,9 +330,9 @@ class ProviderComponent10b implements OnInit {
ProviderComponent6b,
ProviderComponent7,
ProviderComponent8,
ProviderComponent9a,
ProviderComponent9b,
ProviderComponent9,
ProviderComponent10a,
ProviderComponent10b
ProviderComponent10b,
ProviderComponent10c
])
class ProvidersComponent {}

1
public/docs/_examples/dependency-injection/dart/lib/user_service.dart
View File

@ -1,5 +1,4 @@
// #docregion
import 'package:angular2/core.dart';
@Injectable()

2
public/docs/_examples/dependency-injection/dart/pubspec.yaml
View File

@ -5,7 +5,7 @@ version: 0.0.1
environment:
sdk: '>=1.13.0 <2.0.0'
dependencies:
angular2: 2.0.0-beta.11
angular2: 2.0.0-beta.12
browser: ^0.10.0
dart_to_js_script_rewriter: ^0.1.0
transformers:

2
public/docs/_examples/dependency-injection/dart/test/hero_list_component_test.dart
View File

@ -1,6 +1,6 @@
// A simple test
// More details will be in the testing chapter.
import 'package:angular2/angular2.dart';
import 'package:angular2/core.dart';
import 'package:dependency_injection/heroes/hero.dart';
import 'package:dependency_injection/heroes/hero_list_component.dart';
import 'package:dependency_injection/heroes/hero_service.dart';

18
public/docs/_examples/dependency-injection/dart/web/index.html
View File

@ -1,15 +1,15 @@
<!-- #docregion -->
<!--#docregion-->
<!DOCTYPE html>
<html>
<head>
<head>
<title>Dependency Injection</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="styles.css">
<script type="application/dart" src="main.dart"></script>
</head>
<body>
<my-app>Loading my-app ...</my-app>
<my-providers>Loading my-providers ...</my-providers>
</body>
<script defer src="main.dart" type="application/dart"></script>
<script defer src="packages/browser/dart.js"></script>
</head>
<body>
<my-app>Loading...</my-app>
<my-providers>Loading my-providers ...</my-providers>
</body>
</html>

8
public/docs/_examples/dependency-injection/dart/web/main_1.dart
View File

@ -1,10 +1,10 @@
import 'package:angular2/platform/browser.dart';
import 'package:dependency_injection/app_component.dart';
import 'package:dependency_injection/heroes/hero_service.dart';
//#docregion bootstrap
main() {
// Injecting services in bootstrap works but is discouraged
bootstrap(AppComponent, [HeroService]);
//#enddocregion bootstrap
//#docregion bootstrap
bootstrap(AppComponent,
[HeroService]); // DISCOURAGED (but works)
//#enddocregion bootstrap
}

2
public/docs/_examples/dependency-injection/ts/app/injector.component.ts
View File

@ -12,7 +12,7 @@ import {Logger} from './logger.service';
selector: 'my-injectors',
template: `
<h2>Other Injections</h2>
<div id="car"> {{car.drive()}}</div>
<div id="car">{{car.drive()}}</div>
<div id="hero">{{hero.name}}</div>
<div id="rodent">{{rodent}}</div>
`,

280
public/docs/dart/latest/guide/dependency-injection.jade
View File

@ -1,11 +1,279 @@
include ../_util-fns
+includeShared('{ts}', 'intro')
:marked
We're working on the Dart version of this chapter.
In the meantime, please see these resources:
The complete source code for the example app in this chapter is
[in GitHub](https://github.com/angular/angular.io/tree/master/public/docs/_examples/dependency-injection/dart).
* [Dependency Injection](/docs/ts/latest/guide/dependency-injection.html):
The TypeScript version of this chapter
+includeShared('{ts}', 'why-1')
+makeExample('dependency-injection/dart/lib/car/car_no_di.dart', 'car', 'lib/car/car.dart (without DI)')
+includeShared('{ts}', 'why-2')
+makeTabs(
'dependency-injection/dart/lib/car/car.dart, dependency-injection/dart/lib/car/car_no_di.dart',
'car-ctor, car-ctor',
'lib/car/car.dart (excerpt with DI), lib/car/car.dart (excerpt without DI)')(format=".")
+includeShared('{ts}', 'why-3-1')
+includeShared('{ts}', 'why-3-2')
- var stylePattern = { otl: /(new Car.*$)/gm };
+makeExample('dependency-injection/dart/lib/car/car_creations.dart', 'car-ctor-instantiation', '', stylePattern)(format=".")
+includeShared('{ts}', 'why-4')
.l-sub-section
:marked
The _consumer_ of `Car` has the problem. The consumer must update the car creation code to
something like this:
- var stylePattern = { otl: /(new Car.*$)/gm };
+makeExample('dependency-injection/dart/lib/car/car_creations.dart', 'car-ctor-instantiation-with-param', '', stylePattern)(format=".")
:marked
The critical point is this: `Car` itself did not have to change.
We'll take care of the consumer's problem soon enough.
+includeShared('{ts}', 'why-6')
- var stylePattern = { otl: /(new Car.*$)/gm };
+makeExample('dependency-injection/dart/lib/car/car_creations.dart', 'car-ctor-instantiation-with-mocks', '', stylePattern)(format=".")
+includeShared('{ts}', 'why-7')
+makeExample('dependency-injection/dart/lib/car/car_factory.dart', null, 'lib/car/car_factory.dart')
+includeShared('{ts}', 'why-8')
+makeExample('dependency-injection/dart/lib/car/car_injector.dart','injector-call')(format=".")
+includeShared('{ts}', 'why-9')
* [Dart source code](https://github.com/angular/angular.io/tree/master/public/docs/_examples/dependency-injection/dart):
A preliminary version of the example code that will appear in this chapter
+includeShared('{ts}', 'di-1')
+makeTabs(
`dependency-injection/dart/lib/heroes/heroes_component_1.dart,
dependency-injection/dart/lib/heroes/hero_list_component_1.dart,
dependency-injection/dart/lib/heroes/hero.dart,
dependency-injection/dart/lib/heroes/mock_heroes.dart`,
'v1,,,',
`lib/heroes/heroes_component.dart,
lib/heroes/hero_list_component.dart,
lib/heroes/hero.dart,
lib/heroes/mock_heroes.dart`)
+includeShared('{ts}', 'di-2')
+includeShared('{ts}', 'di-3')
+makeExample('dependency-injection/dart/lib/heroes/hero_service_1.dart',null, 'lib/heroes/hero_service.dart' )
+includeShared('{ts}', 'di-4')
.l-sub-section
:marked
We aren't even pretending this is a real service.
If we were actually getting data from a remote server, the API would have to be asynchronous,
returning a `Future`.
We'd also have to rewrite the way components consume our service.
This is important in general, but not to our current story.
+includeShared('{ts}', 'di-6')
+includeShared('{ts}', 'di-configure-injector-1')
+makeExample('dependency-injection/dart/web/main.dart', 'bootstrap', 'web/main.dart (excerpt)')(format='.')
+includeShared('{ts}', 'di-configure-injector-2')
+makeExample('dependency-injection/dart/web/main_1.dart', 'bootstrap')(format='.')
+includeShared('{ts}', 'di-configure-injector-3')
+includeShared('{ts}', 'di-register-providers-1')
+makeExample('dependency-injection/dart/lib/heroes/heroes_component_1.dart',null,'lib/heroes/heroes_component.dart')
+includeShared('{ts}', 'di-register-providers-2')
+makeExample('dependency-injection/dart/lib/heroes/heroes_component_1.dart','providers')(format='.')
+includeShared('{ts}', 'di-register-providers-3')
+includeShared('{ts}', 'di-prepare-for-injection-1')
+makeTabs(
`dependency-injection/dart/lib/heroes/hero_list_component_2.dart,
dependency-injection/dart/lib/heroes/hero_list_component_1.dart`,
null,
`lib/heroes/hero_list_component (with DI),
lib/heroes/hero_list_component (without DI)`)
.l-sub-section
:marked
### Focus on the constructor
Adding a parameter to the constructor isn't all that's happening here.
+makeExample('dependency-injection/dart/lib/heroes/hero_list_component_2.dart', 'ctor')(format=".")
:marked
The constructor parameter has a type: `HeroService`.
The `HeroListComponent` class is also annotated with `@Component`
(scroll up to confirm that fact).
Also recall that the parent component (`HeroesComponent`)
has `providers` information for `HeroService`.
The constructor parameter type, the `@Component` annotation,
and the parent's `providers` information combine to tell the
Angular injector to inject an instance of
`HeroService` whenever it creates a new `HeroListComponent`.
+includeShared('{ts}', 'di-create-injector-implicitly-1')
+makeExample('dependency-injection/dart/lib/car/car_injector.dart','injector-create-and-call')(format=".")
+includeShared('{ts}', 'di-create-injector-implicitly-2')
+includeShared('{ts}', 'di-singleton-services')
// Skip the testing section, for now.
// includeShared('{ts}', 'di-testing-component-1')
// includeShared('{ts}', 'di-testing-component-2')
+includeShared('{ts}', 'di-service-service-1')
+makeTabs(
`dependency-injection/dart/lib/heroes/hero_service_2.dart,
dependency-injection/dart/lib/heroes/hero_service_1.dart`,
null,
`lib/heroes/hero_service (v.2),
lib/heroes/hero_service (v.1)`)
+includeShared('{ts}', 'di-service-service-2')
+includeShared('{ts}', 'di-injectable-1')
:marked
Forgetting the `@Injectable()` can cause a runtime error:
code-example(format, language="html").
Cannot find reflection information on &lt;Type>
+includeShared('{ts}', 'di-injectable-2')
.callout.is-critical
header Always include the parentheses
:marked
Always use `@Injectable()`, not just `@Injectable`.
A metadata annotation must be either a reference to a
compile-time constant variable or a call to a constant
constructor such as `Injectable()`.
If we forget the parentheses, the analyzer will complain:
"Annotation creation must have arguments". If we try to run the
app anyway, it won't work, and the console will say
"expression must be a compile-time constant".
+includeShared('{ts}', 'logger-service-1')
+makeExample(
'dependency-injection/dart/lib/logger_service.dart',null, 'lib/logger_service')
.l-sub-section
:marked
### Implementing a logger
Our examples use a simple logger.
A real implementation would probably use the
[logging package](https://pub.dartlang.org/packages/logging).
:marked
We're likely to need the same logger service everywhere in our application,
so we put it in the `lib/` folder, and
we register it in the `providers` array of the metadata for our application root component, `AppComponent`.
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-logger', 'lib/app_component.dart (excerpt)')
+includeShared('{ts}', 'logger-service-3')
+includeShared('{ts}', 'logger-service-4')
+includeShared('{ts}', 'logger-service-5')
+makeExample('dependency-injection/dart/lib/providers_component.dart','provider-10-ctor')(format='.')
+includeShared('{ts}', 'logger-service-6')
+makeExample('dependency-injection/dart/lib/providers_component.dart','provider-10-logger')(format='.')
+includeShared('{ts}', 'logger-service-7')
+includeShared('{ts}', 'providers-1')
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-logger')
+includeShared('{ts}', 'providers-2')
+includeShared('{ts}', 'providers-provide-1')
:marked
### The *Provider* class
+includeShared('{ts}', 'providers-provide-1-1')
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-1')
+includeShared('{ts}', 'providers-provide-2')
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-2')
// includeShared('{ts}', 'providers-provide-3')
// includeShared('{ts}', 'providers-provide-4-1')
// Don't discuss provide function.
:marked
We supply two arguments (or more) to the `Provider` constructor.
+includeShared('{ts}', 'providers-provide-4-2')
:marked
The second is a named parameter, such as `useClass`,
that we can think of as a *recipe* for creating the dependency value.
There are many ways to create dependency values... and many ways to write a recipe.
+includeShared('{ts}', 'providers-alternative-1')
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-4')
.callout.is-helpful
header Dart difference: Constants in metadata
:marked
In Dart, the value of a metadata annotation must be a compile-time constant.
For that reason, we can't call functions to get values
to use within an annotation.
Instead, we use constant literals or constant constructors.
For example, a TypeScript program might use the
function call `provide(Logger, {useClass: BetterLogger})`,
which is equivalent to the TypeScript code
`new Provider(Logger, {useClass: BetterLogger})`.
A Dart annotation would instead use the constant value `const Provider(Logger, useClass: BetterLogger)`.
+includeShared('{ts}', 'providers-alternative-2')
+makeExample('dependency-injection/dart/lib/providers_component.dart','EvenBetterLogger')
+includeShared('{ts}', 'providers-alternative-3')
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-5')(format=".")
+includeShared('{ts}', 'providers-aliased-1')
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-6a')(format=".")
+includeShared('{ts}', 'providers-aliased-2')
- var stylePattern = { otl: /(useExisting.*\))/gm };
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-6b','', stylePattern)(format=".")
+includeShared('{ts}', 'providers-value-1')
:marked
We can provide objects directly,
instead of asking the injector to create an instance of a class,
by specifying a `useValue` parameter to `Provider`.
Because Dart annotations must be compile-time constants,
`useValue` is often used with string or list literals.
However, `useValue` works with any constant object.
To create a class that can provide constant objects,
make sure all its instance variables are `final`,
and give it a `const` constructor:
+makeExample('dependency-injection/dart/lib/app_config.dart','const-class','lib/app_config.dart (excerpt)')(format='.')
:marked
Create a constant instance of the class by using `const` instead of `new`:
+makeExample('dependency-injection/dart/lib/app_config.dart','const-object','lib/app_config.dart (excerpt)')(format='.')
:marked
Then specify the object using the `useValue` argument to `Provider`:
- var stylePattern = { otl: /(useValue.*\))/gm };
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-9','', stylePattern)(format='.')
:marked
See more `useValue` examples in the
[Non-class dependencies](#non-class-dependencies) and
[OpaqueToken](#opaquetoken) sections.
+includeShared('{ts}', 'providers-factory-1')
+makeExample('dependency-injection/dart/lib/heroes/hero_service.dart','internals', 'lib/heroes/hero_service.dart (excerpt)')(format='.')
+includeShared('{ts}', 'providers-factory-2')
+makeExample('dependency-injection/dart/lib/heroes/hero_service_provider.dart','factory', 'lib/heroes/hero_service_provider.dart (excerpt)')(format='.')
+includeShared('{ts}', 'providers-factory-3')
+makeExample('dependency-injection/dart/lib/heroes/hero_service_provider.dart','provider', 'lib/heroes/hero_service_provider.dart (excerpt)')(format='.')
+includeShared('{ts}', 'providers-factory-4')
+includeShared('{ts}', 'providers-factory-5')
- var stylePattern = { otl: /(providers.*),$/gm };
+makeTabs(
`dependency-injection/dart/lib/heroes/heroes_component.dart,
dependency-injection/dart/lib/heroes/heroes_component_1.dart`,
null,
`lib/heroes/heroes_component (v.3),
lib/heroes/heroes_component (v.2)`,
stylePattern)
+includeShared('{ts}', 'tokens-1')
+makeExample('dependency-injection/dart/lib/injector_component.dart','get-hero-service')(format='.')
+includeShared('{ts}', 'tokens-2')
// [PENDING: How about a better name than ProviderComponent8?]
+makeExample('dependency-injection/dart/lib/providers_component.dart','provider-8-ctor')(format=".")
+includeShared('{ts}', 'tokens-3')
.callout.is-helpful
header Dart difference: Interfaces are valid tokens
:marked
In TypeScript, interfaces don't work as provider tokens.
Dart doesn't have this problem;
every class implicitly defines an interface,
so interface names are just class names.
+includeShared('{ts}', 'tokens-non-class-deps-1')
:marked
We know we can register an object with a [value provider](#value-provider).
But what do we use for the token?
+includeShared('{ts}', 'tokens-opaque-1')
+makeExample('dependency-injection/dart/lib/providers_component.dart','opaque-token')(format='.')
+includeShared('{ts}', 'tokens-opaque-2')
+makeExample('dependency-injection/dart/lib/providers_component.dart','use-opaque-token')(format=".")
:marked
Here's an example of providing configuration information
for an injected class. First define the class:
+makeExample('dependency-injection/dart/lib/providers_component.dart','configurable-logger')(format=".")
:marked
Then inject that class and its configuration information:
+makeExample('dependency-injection/dart/lib/providers_component.dart','providers-7')(format=".")
+includeShared('{ts}', 'summary')
+includeShared('{ts}', 'appendix-explicit-injector-1')
+makeExample('dependency-injection/dart/lib/injector_component.dart', 'injector', 'lib/injector_component.dart')
+includeShared('{ts}', 'appendix-explicit-injector-2')

351
public/docs/ts/latest/guide/dependency-injection.jade
View File

@ -1,4 +1,6 @@
include ../_util-fns
// #docregion intro
:marked
**Dependency injection** is an important application design pattern.
Angular has its own dependency injection framework, and
@ -7,18 +9,21 @@ include ../_util-fns
In this chapter we'll learn what DI is and why we want it.
Then we'll learn [how to use it](#angular-di) in an Angular app.
// #enddocregion intro
:marked
[Run the live example](/resources/live-examples/dependency-injection/ts/plnkr.html)
// #docregion why-1
<a id="why-di"></a>
.l-main-section
:marked
## Why dependency injection?
Let's start with the following code.
// #enddocregion why-1
+makeExample('dependency-injection/ts/app/car/car-no-di.ts', 'car', 'app/car/car.ts (without DI)')
// #docregion why-2
- var lang = current.path[1]
- var prefix = lang == 'dart' ? '' : 'this.'
:marked
Our `Car` creates everything it needs inside its constructor.
What's the problem?
@ -31,7 +36,7 @@ include ../_util-fns
What if the `Engine` class evolves and its constructor requires a parameter?
Our `Car` is broken and stays broken until we rewrite it along the lines of
`this.engine = new Engine(theNewParameter)`.
`#{prefix}engine = new Engine(theNewParameter)`.
We didn't care about `Engine` constructor parameters when we first wrote `Car`.
We don't really care about them now.
But we'll *have* to start caring because
@ -58,40 +63,45 @@ include ../_util-fns
if we can't swap in low-pressure tires during the test?
We have no control over the car's hidden dependencies.
When we can't control the dependencies, a class become difficult to test.
When we can't control the dependencies, a class becomes difficult to test.
How can we make `Car` more robust, flexible, and testable?
That's super easy. We probably already know what to do. We change our `Car` constructor to a version with DI:
That's super easy. We change our `Car` constructor to a version with DI:
<a id="ctor-injection"></a>
// #enddocregion why-2
+makeTabs(
'dependency-injection/ts/app/car/car.ts, dependency-injection/ts/app/car/car-no-di.ts',
'car-ctor, car-ctor',
'app/car/car.ts (excerpt with DI), app/car/car.ts (excerpt without DI)')(format=".")
// #docregion why-3-1
:marked
See what happened? We moved the definition of the dependencies to the constructor.
Our `Car` class no longer creates an engine or tires.
It just consumes them.
// #enddocregion why-3-1
// TypeScript only
.l-sub-section
:marked
We also leverage TypeScript's constructor syntax for declaring parameters and properties simultaneously.
// #docregion why-3-2
:marked
Now we create a car by passing the engine and tires to the constructor.
// #enddocregion why-3-2
- var stylePattern = { otl: /(new Car.*$)/gm };
+makeExample('dependency-injection/ts/app/car/car-creations.ts', 'car-ctor-instantiation', '', stylePattern)(format=".")
// #docregion why-4
:marked
How cool is that?
The definition of the engine and tire dependencies are decoupled from the `Car` class itself.
The definition of the engine and tire dependencies are
decoupled from the `Car` class itself.
We can pass in any kind of engine or tires we like, as long as they
conform to the general API requirements of an engine or tires.
If someone extends the `Engine` class, that is not `Car`'s problem.
// #enddocregion why-4
// Must copy the following, due to indented +make.
.l-sub-section
:marked
The _consumer_ of `Car` has the problem. The consumer must update the car creation code to
@ -103,16 +113,16 @@ include ../_util-fns
:marked
The critical point is this: `Car` itself did not have to change.
We'll take care of the consumer's problem soon enough.
// #docregion why-6
:marked
The `Car` class is much easier to test because we are in complete control
of its dependencies.
We can pass mocks to the constructor that do exactly what we want them to do
during each test:
// #enddocregion why-6
- var stylePattern = { otl: /(new Car.*$)/gm };
+makeExample('dependency-injection/ts/app/car/car-creations.ts', 'car-ctor-instantiation-with-mocks', '', stylePattern)(format=".")
// #docregion why-7
:marked
**We just learned what dependency injection is**.
@ -126,9 +136,9 @@ include ../_util-fns
We need something that takes care of assembling these parts for us.
We could write a giant class to do that:
// #enddocregion why-7
+makeExample('dependency-injection/ts/app/car/car-factory.ts', null, 'app/car/car-factory.ts')
// #docregion why-8
:marked
It's not so bad now with only three creation methods.
But maintaining it will be hairy as the application grows.
@ -143,9 +153,9 @@ include ../_util-fns
We register some classes with this injector, and it figures out how to create them.
When we need a `Car`, we simply ask the injector to get it for us and we're good to go.
// #enddocregion why-8
+makeExample('dependency-injection/ts/app/car/car-injector.ts','injector-call')(format=".")
// #docregion why-9
:marked
Everyone wins. The `Car` knows nothing about creating an `Engine` or `Tires`.
The consumer knows nothing about creating a `Car`.
@ -156,7 +166,8 @@ include ../_util-fns
Now that we know what dependency injection is and appreciate its benefits,
let's see how it is implemented in Angular.
// #enddocregion why-9
// #docregion di-1
<a id="angular-di"></a>
.l-main-section
:marked
@ -170,7 +181,7 @@ include ../_util-fns
We'll begin with a simplified version of the `HeroesComponent`
that we built in the [The Tour of Heroes](../tutorial/).
// #enddocregion di-1
+makeTabs(
`dependency-injection/ts/app/heroes/heroes.component.1.ts,
dependency-injection/ts/app/heroes/hero-list.component.1.ts,
@ -181,34 +192,36 @@ include ../_util-fns
app/heroes/hero-list.component.ts,
app/heroes/hero.ts,
app/heroes/mock-heroes.ts`)
// #docregion di-2
:marked
The `HeroesComponent` is the root component of the *Heroes* feature area.
It governs all the child components of this area.
Our stripped down version has only one child, `HeroListComponent`,
which displays a list of heroes.
.l-sub-section
:marked
Do we really need so many files? Of course not!
We're going *beyond* the strictly necessary
in order to illustrate patterns that work well in real applications.
// #enddocregion di-2
// #docregion di-3
:marked
Right now `HeroListComponent` gets heroes from `HEROES`, an in-memory collection
defined in another file and imported by this component.
defined in another file.
That may suffice in the early stages of development, but it's far from ideal.
As soon as we try to test this component or want to get our heroes data from a remote server,
we'll have to change the implementation of `heroes` and
fix every other use of the `HEROES` mock data.
Let's make a service that hides how we get hero data.
// #enddocregion di-3
// Unnecessary for Dart
.l-sub-section
:marked
Write this service in its own file. See [this note](#forward-ref) to understand why.
+makeExample('dependency-injection/ts/app/heroes/hero.service.1.ts',null, 'app/heroes/hero.service.ts' )
// #docregion di-4
:marked
Our `HeroService` exposes a `getHeroes` method that returns
the same mock data as before, but none of its consumers need to know that.
// #enddocregion di-4
// #docregion di-5
.l-sub-section
:marked
We aren't even pretending this is a real service.
@ -217,24 +230,30 @@ include ../_util-fns
[ES2015 promises](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise).
We'd also have to rewrite the way components consume our service.
This is important in general, but not to our current story.
// #enddocregion di-5
// #docregion di-6
:marked
A service is nothing more than a class in Angular 2.
It remains nothing more than a class until we register it with an Angular injector.
// #enddocregion di-6
// #docregion di-configure-injector-1
:marked
### Configuring the injector
<a id="bootstrap"></a>
We don't have to create an Angular injector.
Angular creates an application-wide injector for us during the bootstrap process.
// #enddocregion di-configure-injector-1
+makeExample('dependency-injection/ts/app/main.ts', 'bootstrap', 'app/main.ts (excerpt)')(format='.')
// #docregion di-configure-injector-2
:marked
We do have to configure the injector by registering the **providers**
that create the services our application requires.
We'll explain what [providers](#providers) are later in this chapter.
Before we do, let's see an example of provider registration during bootstrapping:
// #enddocregion di-configure-injector-2
+makeExample('dependency-injection/ts/app/main.1.ts', 'bootstrap')(format='.')
// #docregion di-configure-injector-3
:marked
The injector now knows about our `HeroService`.
An instance of our `HeroService` will be available for injection across our entire application.
@ -247,36 +266,42 @@ include ../_util-fns
The preferred approach is to register application providers in application components.
Because the `HeroService` is used within the *Heroes* feature area &mdash;
and nowhere else &mdash; the ideal place to register it is in the top-level `HeroesComponent`.
// #enddocregion di-configure-injector-3
// #docregion di-register-providers-1
:marked
### Registering providers in a component
Here's a revised `HeroesComponent` that registers the `HeroService`.
// #enddocregion di-register-providers-1
+makeExample('dependency-injection/ts/app/heroes/heroes.component.1.ts',null,'app/heroes/heroes.component.ts')
// #docregion di-register-providers-2
:marked
Look closely at the `providers` part of the `@Component` metadata:
// #enddocregion di-register-providers-2
+makeExample('dependency-injection/ts/app/heroes/heroes.component.1.ts','providers')(format='.')
// #docregion di-register-providers-3
:marked
An instance of the `HeroService` is now available for injection in this `HeroesComponent`
and all of its child components.
The `HeroesComponent` itself doesn't happen to need the `HeroService`.
But its child `HeroListComponent` does, so we head there next.
// #enddocregion di-register-providers-3
// #docregion di-prepare-for-injection-1
:marked
### Preparing the HeroListComponent for injection
The `HeroListComponent` should get heroes from the injected `HeroService`.
Per the dependency injection pattern, the component must ask for the service in its constructor, [as we explained
earlier](#ctor-injection).
It's a small change:
// #enddocregion di-prepare-for-injection-1
+makeTabs(
`dependency-injection/ts/app/heroes/hero-list.component.2.ts,
dependency-injection/ts/app/heroes/hero-list.component.1.ts`,
null,
`app/heroes/hero-list.component (with DI),
app/heroes/hero-list.component (without DI)`)
:marked
// Must copy the following, due to indented +make.
.l-sub-section
:marked
### Focus on the constructor
@ -285,6 +310,7 @@ include ../_util-fns
+makeExample('dependency-injection/ts/app/heroes/hero-list.component.2.ts', 'ctor')(format=".")
// TypeScript only
:marked
We're writing in TypeScript and have followed the parameter name with a type annotation, `:HeroService`.
The class is also decorated with the `@Component` decorator (scroll up to confirm that fact).
@ -295,14 +321,15 @@ include ../_util-fns
That's how the Angular injector knows to inject an instance of the `HeroService` when it
creates a new `HeroListComponent`.
<a id="di-metadata"></a>
// #docregion di-create-injector-implicitly-1
:marked
<a id="di-metadata"></a>
### Creating the injector (implicitly)
When we introduced the idea of an injector above, we showed how to create
an injector and use it to create a new `Car`.
// #enddocregion di-create-injector-implicitly-1
+makeExample('dependency-injection/ts/app/car/car-injector.ts','injector-create-and-call')(format=".")
// #docregion di-create-injector-implicitly-2
:marked
We won't find code like that in the Tour of Heroes or any of our other samples.
We *could* write [code with an explicit injector](#explicit-injector) if we *had* to, but we rarely do.
@ -310,7 +337,9 @@ include ../_util-fns
when it creates components for us &mdash; whether through HTML markup, as in `<hero-list></hero-list>`,
or after navigating to a component with the [router](./router.html).
If we let Angular do its job, we'll enjoy the benefits of automated dependency injection.
// #enddocregion di-create-injector-implicitly-2
// #docregion di-singleton-services
:marked
### Singleton services
Dependencies are singletons within the scope of an injector.
In our example, a single `HeroService` instance is shared among the
@ -319,19 +348,25 @@ include ../_util-fns
However, Angular DI is an hierarchical injection
system, which means that nested injectors can create their own service instances.
Learn more about that in the [Hierarchical Injectors](./hierarchical-dependency-injection.html) chapter.
// #enddocregion di-singleton-services
// Skip this for Dart, for now
// #docregion di-testing-component-1
:marked
### Testing the component
We emphasized earlier that designing a class for dependency injection makes the class easier to test.
Listing dependencies as constructor parameters may be all we need to test application parts effectively.
For example, we can create a new `HeroListComponent` with a mock service that we can manipulate
under test:
// #enddocregion di-testing-component-1
+makeExample('dependency-injection/ts/app/test.component.ts', 'spec')(format='.')
// #docregion di-testing-component-2
.l-sub-section
:marked
Learn more in [Testing](../testing/index.html).
// #enddocregion di-testing-component-2
// #docregion di-service-service-1
:marked
### When the service needs a service
Our `HeroService` is very simple. It doesn't have any dependencies of its own.
@ -342,49 +377,61 @@ include ../_util-fns
adding a constructor that takes a `Logger` parameter.
Here is the revision compared to the original.
// #enddocregion di-service-service-1
+makeTabs(
`dependency-injection/ts/app/heroes/hero.service.2.ts,
dependency-injection/ts/app/heroes/hero.service.1.ts`,
null,
`app/heroes/hero.service (v.2),
app/heroes/hero.service (v.1)`)
// #docregion di-service-service-2
:marked
The constructor now asks for an injected instance of a `Logger` and stores it in a private property called `_logger`.
We call that property within our `getHeroes` method when anyone asks for heroes.
// #enddocregion di-service-service-2
// #docregion di-injectable-1
- var lang = current.path[1]
- var decoration = lang == 'dart' ? 'annotation' : 'decoration'
- var tsmetadata = lang == 'ts' ? 'As <a href="#di-metadata">we mentioned earlier</a>, <b>TypeScript only generates metadata for classes that have a decorator.</b>' : ''
:marked
<a id="injectable"></a>
### Why @Injectable?
Notice the `@Injectable()` decoration above the service class.
Notice the `@Injectable()` #{decoration} above the service class.
We haven't seen `@Injectable()` before.
As it happens, we could have added it to our first version of `HeroService`.
We didn't bother because we didn't need it then.
We need it now... now that our service has an injected dependency.
We need it because Angular requires constructor parameter metadata in order to inject a `Logger`.
As [we mentioned earlier](#di-metadata), **TypeScript only generates metadata for classes that have a decorator.**
We need it because Angular requires constructor parameter metadata in order to inject a `Logger`. !{tsmetadata}
// #enddocregion di-injectable-1
// #docregion di-injectable-2
- var lang = current.path[1]
- var a_decorator = lang == 'dart' ? 'an annotation' : 'a decorator'
- var decorated = lang == 'dart' ? 'annotated' : 'decorated'
- var any_decorator = lang == 'dart' ? '' : 'TypeScript generates metadata for any class with a decorator, and any decorator will do.'
.callout.is-helpful
header Always add @Injectable()
:marked
We recommend adding `@Injectable()` to every service class, even those that don't have dependencies
and, therefore, do not technically require it. Here's why:
ul(style="font-size:inherit")
li <b>Future proofing:</b> No need to remember <code>@Injectable</code> when we add a dependency later.
li <b>Consistency:</b> All services follow the same rules, and we don't have to wonder why a decorator is missing.
li <b>Future proofing:</b> No need to remember <code>@Injectable()</code> when we add a dependency later.
li <b>Consistency:</b> All services follow the same rules, and we don't have to wonder why #{a_decorator} is missing.
.l-sub-section
:marked
The `HeroesComponent` has an injected dependency too. Why don't we add `@Injectable()` to the `HeroesComponent`?
We *can* add it if we really want to. It isn't necessary because the `HeroesComponent` is already decorated with `@Component`.
TypeScript generates metadata for *any* class with a decorator, and *any* decorator will do.
.alert.is-critical
We *can* add it if we really want to. It isn't necessary because
the `HeroesComponent` is already #{decorated} with `@Component`. #{any_decorator}
// #enddocregion di-injectable-2
.callout.is-critical
header Always include the parentheses
:marked
**Always include the parentheses!** Always call `@Injectable()`.
Always use `@Injectable()`, not just `@Injectable`.
Our application will fail mysteriously if we forget the parentheses.
// #docregion logger-service-1
.l-main-section
:marked
## Creating and registering a logger service
@ -393,18 +440,23 @@ include ../_util-fns
1. Register it with the application.
The logger service implementation is no big deal.
// #enddocregion logger-service-1
+makeExample(
'dependency-injection/ts/app/logger.service.ts',null, 'app/logger.service')
// Copied into Dart, due to different directory structure
:marked
We're likely to need the same logger service everywhere in our application,
so we put it at the root level of the application in the `app/` folder, and
we register it in the `providers` array of the metadata for our application root component, `AppComponent`.
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-logger', 'app/app.component.ts (excerpt)')
// #docregion logger-service-3
:marked
If we forget to register the logger, Angular throws an exception when it first looks for the logger:
code-example(format, language="html").
EXCEPTION: No provider for Logger! (HeroListComponent -> HeroService -> Logger)
// #enddocregion logger-service-3
// #docregion logger-service-4
:marked
That's Angular telling us that the dependency injector couldn't find the *provider* for the logger.
It needed that provider to create a `Logger` to inject into a new
@ -419,20 +471,32 @@ code-example(format, language="html").
Our `HeroService` currently requires a `Logger`. What if we could get by without a logger?
We'd use it if we had it, ignore it if we didn't. We can do that.
// #enddocregion logger-service-4
// TypeScript only?
:marked
First import the `@Optional()` decorator.
+makeExample('dependency-injection/ts/app/providers.component.ts','import-optional')(format='.')
// #docregion logger-service-5
- var lang = current.path[1]
- var rewrite = lang == 'dart' ? 'Just rewrite' : 'Then rewrite'
- var decorator = lang == 'dart' ? 'annotation' : 'decorator'
:marked
Then rewrite the constructor with `@Optional()` decorator preceding the private `_logger` parameter.
#{rewrite} the constructor with the `@Optional()` #{decorator} preceding the private `_logger` parameter.
That tells the injector that `_logger` is optional.
// #enddocregion logger-service-5
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-10-ctor')(format='.')
// #docregion logger-service-6
:marked
Be prepared for a null logger. If we don't register one somewhere up the line,
the injector will inject `null`. We have a method that logs.
What can we do to avoid a null reference exception?
We could substitute a *do-nothing* logger stub so that calling methods continue to work:
// #enddocregion logger-service-6
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-10-logger')(format='.')
// #docregion logger-service-7
:marked
Obviously we'd take a more sophisticated approach if the logger were optional
in multiple locations.
@ -440,7 +504,10 @@ code-example(format, language="html").
But enough about optional loggers. In our sample application, the `Logger` is required.
We must register a `Logger` with the application injector using *providers*,
as we learn in the next section.
// #enddocregion logger-service-7
// #docregion providers-1
:marked
<a id="providers"></a>
.l-main-section
:marked
@ -453,62 +520,94 @@ code-example(format, language="html").
We must register a service *provider* with the injector, or it won't know how to create the service.
Earlier we registered the `Logger` service in the `providers` array of the metadata for the `AppComponent` like this:
// #enddocregion providers-1
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-logger')
// #docregion providers-2
- var lang = current.path[1]
- var implements = lang == 'dart' ? 'implements' : 'looks and behaves like a '
- var objectlike = lang == 'dart' ? '' : 'an object that behaves like '
- var loggerlike = lang == 'dart' ? '' : 'We could provide a logger-like object. '
:marked
The `providers` array appears to hold a service class.
In reality it holds an instance of the [Provider](/docs/ts/latest/api/core/Provider-class.html) class that can create that service.
There are many ways to *provide* something that looks and behaves like a `Logger`.
There are many ways to *provide* something that #{implements} `Logger`.
The `Logger` class itself is an obvious and natural provider &mdash; it has the right shape and it's designed to be created.
But it's not the only way.
We can configure the injector with alternative providers that can deliver an object that behaves like a `Logger`.
We could provide a substitute class. We could provide a logger-like object.
We can configure the injector with alternative providers that can deliver #{objectlike} a `Logger`.
We could provide a substitute class. #{loggerlike}
We could give it a provider that calls a logger factory function.
Any of these approaches might be a good choice under the right circumstances.
What matters is that the injector has a provider to go to when it needs a `Logger`.
// #enddocregion providers-2
// #docregion providers-provide-1
:marked
<a id="provide"></a>
### The *provide* function
// #enddocregion providers-provide-1
// Don't mention provide function in Dart
:marked
### The *Provider* class and *provide* function
// #docregion providers-provide-1-1
:marked
We wrote the `providers` array like this:
// #enddocregion providers-provide-1-1
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-1')
// #docregion providers-provide-2
:marked
This is actually a short-hand expression for a provider registration that creates a new instance of the
[Provider](/docs/ts/latest/api/core/Provider-class.html) class.
// #enddocregion providers-provide-2
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-2')
// #docregion providers-provide-3
// Skip for Dart, where the provide() function won't pass type checking.
:marked
The [provide](/docs/ts/latest/api/core/provide-function.html) function is the more common, friendlier way to create a `Provider`:
// #enddocregion providers-provide-3
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-3')
// #docregion providers-provide-4-1
// Modified for Dart.
:marked
In both approaches &mdash; `Provider` class and `provide` function &mdash;
we supply two arguments.
// #enddocregion providers-provide-4-1
// #docregion providers-provide-4-2
:marked
The first is the [token](#token) that serves as the key for both locating a dependency value
and registering the provider.
// #enddocregion providers-provide-4-2
// Dart is different here (uses an optional parameter)
:marked
The second is a provider definition object,
which we can think of as a *recipe* for creating the dependency value.
There are many ways to create dependency values... and many ways to write a recipe.
// #docregion providers-alternative-1
:marked
<a id="class-provider"></a>
### Alternative class providers
Occasionally we'll ask a different class to provide the service.
The following code tells the injector
to return a `BetterLogger` when something asks for the `Logger`.
// #enddocregion providers-alternative-1
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-4')
// #docregion providers-alternative-2
:marked
### Class provider with dependencies
Maybe an `EvenBetterLogger` could display the user name in the log message.
This logger gets the user from the injected `UserService`,
which happens also to be injected at the application level.
// #enddocregion providers-alternative-2
+makeExample('dependency-injection/ts/app/providers.component.ts','EvenBetterLogger')
// #docregion providers-alternative-3
:marked
Configure it like we did `BetterLogger`.
// #enddocregion providers-alternative-3
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-5')(format=".")
// #docregion providers-aliased-1
:marked
### Aliased class providers
@ -525,16 +624,21 @@ code-example(format, language="html").
We certainly do not want two different `NewLogger` instances in our app.
Unfortunately, that's what we get if we try to alias `OldLogger` to `NewLogger` with `useClass`.
// #enddocregion providers-aliased-1
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-6a')(format=".")
// #docregion providers-aliased-2
:marked
The solution: Alias with the `useExisting` option.
// #enddocregion providers-aliased-2
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-6b')(format=".")
// #docregion providers-value-1
<a id="value-provider"></a>
:marked
### Value providers
// #enddocregion providers-value-1
// Typescript only
:marked
Sometimes it's easier to provide a ready-made object rather than ask the injector to create it from a class.
+makeExample('dependency-injection/ts/app/providers.component.ts','silent-logger')(format=".")
:marked
@ -542,6 +646,7 @@ code-example(format, language="html").
which makes this object play the logger role.
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-7')(format=".")
// #docregion providers-factory-1
<a id="factory-provider"></a>
:marked
### Factory providers
@ -571,20 +676,24 @@ code-example(format, language="html").
Why? We don't know either. Stuff like this happens.
:marked
Instead the `HeroService` constructor takes a boolean flag to control display of secret heroes.
// #enddocregion providers-factory-1
+makeExample('dependency-injection/ts/app/heroes/hero.service.ts','internals', 'app/heroes/hero.service.ts (excerpt)')(format='.')
// #docregion providers-factory-2
:marked
We can inject the `Logger`, but we can't inject the boolean `isAuthorized`.
We'll have to take over the creation of new instances of this `HeroService` with a factory provider.
A factory provider needs a factory function:
// #enddocregion providers-factory-2
+makeExample('dependency-injection/ts/app/heroes/hero.service.provider.ts','factory', 'app/heroes/hero.service.provider.ts (excerpt)')(format='.')
// #docregion providers-factory-3
:marked
Although the `HeroService` has no access to the `UserService`, our factory function does.
We inject both the `Logger` and the `UserService` into the factory provider and let the injector pass them along to the factory function:
// #enddocregion providers-factory-3
+makeExample('dependency-injection/ts/app/heroes/hero.service.provider.ts','provider', 'app/heroes/hero.service.provider.ts (excerpt)')(format='.')
:marked
// #docregion providers-factory-4
.l-sub-section
:marked
The `useFactory` field tells Angular that the provider is a factory function
@ -593,6 +702,8 @@ code-example(format, language="html").
The `deps` property is an array of [provider tokens](#token).
The `Logger` and `UserService` classes serve as tokens for their own class providers.
The injector resolves these tokens and injects the corresponding services into the matching factory function parameters.
// #enddocregion providers-factory-4
// #docregion providers-factory-5
:marked
Notice that we captured the factory provider in an exported variable, `heroServiceProvider`.
This extra step makes the factory provider reusable.
@ -601,6 +712,7 @@ code-example(format, language="html").
In our sample, we need it only in the `HeroesComponent`,
where it replaces the previous `HeroService` registration in the metadata `providers` array.
Here we see the new and the old implementation side-by-side:
// #enddocregion providers-factory-5
+makeTabs(
`dependency-injection/ts/app/heroes/heroes.component.ts,
dependency-injection/ts/app/heroes/heroes.component.1.ts`,
@ -608,6 +720,7 @@ code-example(format, language="html").
`app/heroes/heroes.component (v.3),
app/heroes/heroes.component (v.2)`)
// #docregion tokens-1
<a id="token"></a>
.l-main-section
:marked
@ -620,41 +733,56 @@ code-example(format, language="html").
In all previous examples, the dependency value has been a class *instance*, and
the class *type* served as its own lookup key.
Here we get a `HeroService` directly from the injector by supplying the `HeroService` type as the token:
// #enddocregion tokens-1
+makeExample('dependency-injection/ts/app/injector.component.ts','get-hero-service')(format='.')
// #docregion tokens-2
:marked
We have similar good fortune when we write a constructor that requires an injected class-based dependency.
We define a constructor parameter with the `HeroService` class type,
and Angular knows to inject the
service associated with that `HeroService` class token:
// #enddocregion tokens-2
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-8-ctor')(format=".")
// #docregion tokens-3
:marked
This is especially convenient when we consider that most dependency values are provided by classes.
// #enddocregion tokens-3
// #docregion tokens-non-class-deps-1
- var lang = current.path[1]
- var objectexamples = lang == 'dart' ? 'a string or list literal, or maybe a function' : 'a string, a function, or an object'
// Is function injection useful? Should we show it?
:marked
### Non-class dependencies
What if the dependency value isn't a class?
Sometimes the thing we want to inject is a string, a function, or an object.
Sometimes the thing we want to inject is #{objectexamples}.
// #enddocregion tokens-non-class-deps-1
// TS/JS only
:marked
Applications often define configuration objects with lots of small facts like the title of the application or the address of a web API endpoint.
These configuration objects aren't always instances of a class. They tend to be object hashes like this one:
+makeExample('dependency-injection/ts/app/app.config.ts','config','app/app-config.ts (excerpt)')(format='.')
// TypeScript only?
:marked
We'd like to make this `config` object available for injection.
We know we can register an object with a [value provider](#value-provider).
But what do we use for the token?
We don't have a class to serve as a token. There is no `Config` class.
// begin Typescript only
// Typescript only
<a id="interface"></a>
:marked
### Interfaces aren't valid tokens
.l-sub-section
:marked
### TypeScript interfaces aren't valid tokens
The `CONFIG` constant has an interface, `Config`. Unfortunately, we
cannot use an interface as a token:
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-9a-interface')(format=".")
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-9a-ctor-interface')(format=".")
:marked
cannot use a TypeScript interface as a token:
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-9a-interface')(format=".")
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-9a-ctor-interface')(format=".")
:marked
That seems strange if we're used to dependency injection in strongly typed languages, where
an interface is the preferred dependency lookup key.
@ -662,16 +790,29 @@ code-example(format, language="html").
The TypeScript interface disappears from the generated JavaScript.
There is no interface type information left for Angular to find at runtime.
// end Typescript only
<a id="string-token"></a>
// #docregion tokens-opaque-1
<a id="opaque-token"></a>
- var lang = current.path[1]
- var opaquetoken = lang == 'dart' ? '<code>OpaqueToken</code>' : '<a href="/docs/ts/latest/api/core/OpaqueToken-class.html"><code>OpaqueToken</code></a>'
h3 OpaqueToken
p.
The solution is to define and use an !{opaquetoken}.
The definition looks like this:
// #enddocregion tokens-opaque-1
+makeExample('dependency-injection/ts/app/app.config.ts','token')(format='.')
:marked
### String tokens
Fortunately, we can register any dependency provider with a string token.
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-9a')(format=".")
:marked
Now we inject the configuration object into any constructor that needs it, with
the help of an `@Inject` decorator that tells Angular how to find the configuration dependency value.
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-9a-ctor')(format=".")
We register the dependency provider using the `OpaqueToken` object:
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-9b')(format=".")
// #docregion tokens-opaque-2
- var lang = current.path[1]
- var decorated = lang == 'dart' ? 'annotated' : 'decorated'
- var configuration = lang == 'dart' ? '' : 'configuration'
:marked
Now we can inject the #{configuration} object into any constructor that needs it, with
the help of an `@Inject` #{decorator} that tells Angular how to find the #{configuration} dependency value.
// #enddocregion tokens-opaque-2
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-9b-ctor')(format=".")
// begin Typescript only
.l-sub-section
@ -681,32 +822,13 @@ code-example(format, language="html").
:marked
// end typescript only
<a id="opaque-token"></a>
// Skip for Dart (we have another example)
:marked
### OpaqueToken
Alternatively, we could define and use an [OpaqueToken](/docs/ts/latest/api/core/OpaqueToken-class.html)
rather than rely on magic strings that may collide with other developers' string choices.
The definition looks like this:
+makeExample('dependency-injection/ts/app/app.config.ts','token')(format='.')
:marked
Substitute `APP_CONFIG` for the magic string when registering the provider and defining the constructor parameter:
+makeExample('dependency-injection/ts/app/providers.component.ts','providers-9b')(format=".")
+makeExample('dependency-injection/ts/app/providers.component.ts','provider-9b-ctor')(format=".")
:marked
Here's how we provide and inject the configuration object in our top-level `AppComponent`.
Or we can provide and inject the configuration object in our top-level `AppComponent`.
+makeExample('dependency-injection/ts/app/app.component.ts','providers', 'app/app.component.ts (providers)')(format=".")
+makeExample('dependency-injection/ts/app/app.component.ts','ctor', 'app/app.component.ts (constructor)')(format=".")
.l-sub-section
:marked
Angular itself uses `OpaqueToken` objects to register all of its own non-class dependencies. For example,
[HTTP_PROVIDERS](/docs/ts/latest/api/http/HTTP_PROVIDERS-let.html)
is the `OpaqueToken` associated with an array of providers for persisting data with the Angular `Http` client.
Internally, the `Provider` turns both the string and the class type into an `OpaqueToken`
and keys its *token-provider* map with that.
// #docregion summary
.l-main-section
:marked
## Summary
@ -719,15 +841,18 @@ code-example(format, language="html").
We can learn more about its advanced features, beginning with its support for
nested injectors, in the
[Hierarchical Dependency Injection](hierarchical-dependency-injection.html) chapter.
// #enddocregion summary
// #docregion appendix-explicit-injector-1
.l-main-section
<a id="explicit-injector"></a>
:marked
### Appendix: Working with injectors directly
We rarely work directly with an injector.
Here's an `InjectorComponent` that does.
// #enddocregion appendix-explicit-injector-1
+makeExample('dependency-injection/ts/app/injector.component.ts', 'injector', 'app/injector.component.ts')
// #docregion appendix-explicit-injector-2
:marked
The `Injector` is itself an injectable service.
@ -755,7 +880,9 @@ code-example(format, language="html").
Framework developers may take this approach when they
must acquire services generically and dynamically.
// #enddocregion appendix-explicit-injector-2
// TypeScript only? Unnecessary for Dart
.l-main-section
<a id="forward-ref"></a>
:marked