angular-docs-cn/public/docs/_examples/lifecycle-hooks/ts/app/after-content.component.ts

103 lines
2.7 KiB
TypeScript

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