UpgradeComponent

Experimental Class

What it does

Part of the upgrade/static library for hybrid upgrade apps that support AoT compilation

Allows an AngularJS component to be used from Angular.

How to use

Let's assume that you have an AngularJS component called ng1Hero that needs to be made available in Angular templates.

// This AngularJS component will be "upgraded" to be used in Angular
ng1AppModule.component('ng1Hero', {
  bindings: {hero: '<', onRemove: '&'},
  transclude: true,
  template: `<div class="title" ng-transclude></div>
             <h2>{{ $ctrl.hero.name }}</h2>
             <p>{{ $ctrl.hero.description }}</p>
             <button ng-click="$ctrl.onRemove()">Remove</button>`
});

We must create a Directive that will make this AngularJS component available inside Angular templates.

// This Angular directive will act as an interface to the "upgraded" AngularJS component
@Directive({selector: 'ng1-hero'})
class Ng1HeroComponentWrapper extends UpgradeComponent implements OnInit, OnChanges, DoCheck,
    OnDestroy {
  // The names of the input and output properties here must match the names of the
  // `<` and `&` bindings in the AngularJS component that is being wrapped
  @Input() hero: Hero;
  @Output() onRemove: EventEmitter<void>;
  constructor(@Inject(ElementRef) elementRef: ElementRef, @Inject(Injector) injector: Injector) {
    // We must pass the name of the directive as used by AngularJS to the super
    super('ng1Hero', elementRef, injector);
  }

  // For this class to work when compiled with AoT, we must implement these lifecycle hooks
  // because the AoT compiler will not realise that the super class implements them
  ngOnInit() { super.ngOnInit(); }

  ngOnChanges(changes: SimpleChanges) { super.ngOnChanges(changes); }

  ngDoCheck() { super.ngDoCheck(); }

  ngOnDestroy() { super.ngOnDestroy(); }
}

In this example you can see that we must derive from the UpgradeComponent base class but also provide an @Directive decorator. This is because the AoT compiler requires that this information is statically available at compile time.

Note that we must do the following:

specify the directive's selector (ng1-hero)
specify all inputs and outputs that the AngularJS component expects
derive from UpgradeComponent
call the base class from the constructor, passing
- the AngularJS name of the component (ng1Hero)
- the ElementRef and Injector for the component wrapper

Class Overview

class UpgradeComponent implements OnInit,  OnChanges,  DoCheck,  OnDestroy {
  constructor(name: string, elementRef: ElementRef, injector: Injector)
  
  
  ngOnInit()
  ngOnChanges(changes: SimpleChanges)
  ngDoCheck()
  ngOnDestroy()
}

Class Description

A helper class that should be used as a base class for creating Angular directives that wrap AngularJS components that need to be "upgraded".

Constructor

constructor(name: string, elementRef: ElementRef, injector: Injector)

Create a new UpgradeComponent instance. You should not normally need to do this. Instead you should derive a new class from this one and call the super constructor from the base class.

// This Angular directive will act as an interface to the "upgraded" AngularJS component
@Directive({selector: 'ng1-hero'})
class Ng1HeroComponentWrapper extends UpgradeComponent implements OnInit, OnChanges, DoCheck,
    OnDestroy {
  // The names of the input and output properties here must match the names of the
  // `<` and `&` bindings in the AngularJS component that is being wrapped
  @Input() hero: Hero;
  @Output() onRemove: EventEmitter<void>;
  constructor(@Inject(ElementRef) elementRef: ElementRef, @Inject(Injector) injector: Injector) {
    // We must pass the name of the directive as used by AngularJS to the super
    super('ng1Hero', elementRef, injector);
  }

  // For this class to work when compiled with AoT, we must implement these lifecycle hooks
  // because the AoT compiler will not realise that the super class implements them
  ngOnInit() { super.ngOnInit(); }

  ngOnChanges(changes: SimpleChanges) { super.ngOnChanges(changes); }

  ngDoCheck() { super.ngDoCheck(); }

  ngOnDestroy() { super.ngOnDestroy(); }
}

The name parameter should be the name of the AngularJS directive.
The elementRef and injector parameters should be acquired from Angular by dependency injection into the base class constructor.

Note that we must manually implement lifecycle hooks that call through to the super class. This is because, at the moment, the AoT compiler is not able to tell that the UpgradeComponent already implements them and so does not wire up calls to them at runtime.

Class Details

ngOnInit()

ngOnChanges(changes: SimpleChanges)

ngDoCheck()

ngOnDestroy()

exported from upgrade-static-index, defined in upgrade/static/src/static/upgrade_component.ts

© 2010–2017 Google, Inc.
Licensed under the Creative Commons Attribution License 4.0.
https://angular.io/docs/ts/latest/api/upgrade/static/index/UpgradeComponent-class.html