Posted in Javascript onMarch 05, 2018
现在,我们写一个组件puppiesListCmp,用于显示小狗狗的列表:
//puppies-list.component.ts @Component({ selector: 'puppies-list', template: ` <div *ngFor="let puppy of puppies"> <span>{{puppy.name}}</span> <span>{{puppy.age}}</span> <span>{{puppy.color}}</span> </div> ` }) export class puppiesListCmp{ @Input() puppies: Puppy[]; } interface Puppy { name: string, age: number, color: string }
然后这样使用:
//app.component.ts @Component({ selector: 'my-app', template: ` <puppies-list [puppies]="puppies"></puppies-list> ` }) export class App{ puppies = [ { name: "sam", age: 0.6, color: "yellow" }, { name: "bingo", age: 1.5, color: "black" } ] }
效果就行这样:
但是,我希望我们的puppiesListCmp组件可以满足不同的需求,比如在数据不变的情况下只显示小狗狗的name和color,就像这样:
这就是本文的重点了。我们需要实现用户自定义模板!
现在我们不写死组件的模板了,而是让用户从外部输入!
首先,我们的组件模板:
<div *ngFor="let puppy of puppies"> <span>{{puppy.name}}</span> <span>{{puppy.age}}</span> <span>{{puppy.color}}</span> </div>
等价于:
<ng-template ngFor let-puppy [ngForOf]="puppies"> <div> <span>{{puppy.name}}</span> <span>{{puppy.age}}</span> <span>{{puppy.color}}</span> </div> </ng-template>
然后,用@ContentChild(关于@ContentChild可以查看这里,需FQ)获取到外部(相对puppiesListCmp组件而言)自定义模板,并赋给ngForTemplate。也就是说,这部分:
<div> <span>{{puppy.name}}</span> <span>{{puppy.age}}</span> <span>{{puppy.color}}</span> </div>
不再像之前那样写死在组件里了,而是由使用者在父组件中自定义,然后利用Angular的内容投射(Content Projection),投射到puppiesListCmp组件里面。就像这样:
//puppies-list.component.ts import { Component, Input, ContentChild, TemplateRef } from '@angular/core'; import { NgForOfContext } from '@angular/common'; @Component({ selector: 'puppies-list', template: ` <ng-template ngFor let-puppy [ngForOf]="puppies" [ngForTemplate]="tpl"></ng-template> ` }) export class puppiesListCmp{ @Input() puppies: Puppy[]; @ContentChild(TemplateRef) tpl: TemplateRef<NgForOfContext<Puppy>> } interface Puppy { name: string, age: number, color: string }
这样我们的组件就算完成了。然后我们使用它:
//app.component.ts @Component({ selector: 'my-app', template: ` <puppies-list [puppies]="puppies"> <ng-template let-puppy> <div> <span>{{puppy.name}}</span> <span>{{puppy.age}}</span> <span>{{puppy.color}}</span> </div> </ng-template> </puppies-list> ` })
效果还是一样的:
如果我们只要显示小狗狗的name和color,只要这样写就好了:
//app.component.ts @Component({ selector: 'my-app', template: ` <puppies-list [puppies]="puppies"> <ng-template let-puppy> <div> <span>{{puppy.name}}</span> <span>{{puppy.color}}</span> </div> </ng-template> </puppies-list> ` })
效果就像这样:
这样的组件很灵活,想要什么样的效果都可以定制,这就实现了组件的复用。
好了,本文就到此为止了。不当之处,欢迎指出!希望对大家的学习有所帮助,也希望大家多多支持三水点靠木。
Angular利用内容投射向组件输入ngForOf模板的方法
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