81 lines
		
	
	
		
			2.2 KiB
		
	
	
	
		
			TypeScript
		
	
	
	
	
	
			
		
		
	
	
			81 lines
		
	
	
		
			2.2 KiB
		
	
	
	
		
			TypeScript
		
	
	
	
	
	
// #docregion
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import {
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  Component, Input, Output,
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  AfterContentInit,  ContentChild,
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  AfterViewChecked, AfterViewInit, ViewChild
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} from 'angular2/core';
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import {ChildComponent} from './child.component';
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import {LoggerService}  from './logger.service';
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@Component({
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  selector: 'after-view-parent',
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  template: `
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  <div class="parent">
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    <h2>AfterView</h2>
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    <div>
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      <input [(ngModel)]="hero">
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      <button (click)="showChild = !showChild">Toggle child view</button>
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      <my-child *ngIf="showChild" [hero]="hero"></my-child>
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    </div>
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    <h4>-- Lifecycle Hook Log --</h4>
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    <div *ngFor="#msg of hookLog">{{msg}}</div>
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  </div>
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  `,
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  styles: ['.parent {background: burlywood; padding: 8px; margin:100px 8px;}'],
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  directives: [ChildComponent],
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  providers:[LoggerService]
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})
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export class AfterViewParentComponent
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  implements AfterContentInit, AfterViewChecked, AfterViewInit {
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  private _logger:LoggerService;
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  constructor(logger:LoggerService){
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    this._logger = logger;
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    this.hookLog = logger.logs;
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    logger.log('AfterView ctor: ' + this._getMessage());
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  }
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  hookLog:string[];
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  hero = 'Magneta';
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  showChild = true;
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  // Query for a CONTENT child of type `ChildComponent`
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  // No such CONTENT child exists!
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  // This component holds a view but no content of that type.
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  @ContentChild(ChildComponent) contentChild: ChildComponent;
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  // Query for a VIEW child of type `ChildComponent`
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  @ViewChild(ChildComponent) viewChild: ChildComponent;
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  ///// Hooks
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  ngAfterContentInit() {
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    this._logger.log(`AfterContentInit: There is ${this.contentChild ? 'a' : 'no'} content child`);
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  }
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  ngAfterViewInit() {
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    // viewChild is set after the view has been initialized
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    this._logger.log('AfterViewInit: ' + this._getMessage());
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  }
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  private _prevHero:string;
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  ngAfterViewChecked() {
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    // viewChild is updated after the view has been checked
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    // Called frequently; only report when the hero changes
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    if (!this.viewChild || this._prevHero === this.viewChild.hero) {return;}
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    this._prevHero = this.viewChild.hero;
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    this._logger.log('AfterViewChecked: ' + this._getMessage());
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  }
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  private _getMessage(): string {
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    let cmp = this.viewChild;
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    return cmp ? `"${cmp.hero}" child view` : 'no child view';
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  }
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}
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