angular内容投影详解

2022-04-16 08:07:56 来源：易采站长站作者：

单内容投影

利用ng-content来实现

<!-- 组件 - app-content-single --><div>  <h2>标题</h2>  <!-- 投影内容显示位置 -->  <ng-content></ng-content></div><!-- 使用 --><app-content-single>  <div>this is content</div></app-content-single>

多内容投影

利用ng-content来实现

<!-- 组件 - app-content-more --><div>  <h3>Herder Title</h3>  <ng-content select=".header"></ng-content>  <h3>Body Title</h3>  <ng-content select="[body]"></ng-content>  <h3>Default Title</h3>  <ng-content></ng-content>  <h3>Footer Title</h3>  <ng-content select="footer"></ng-content></div><!-- 使用 --><app-content-more>  <div>this is default01</div>  <div class="header">this is header</div>  <div>this is default02</div>  <div body>this is body</div>  <div>this is default03</div>  <footer>this is footer</footer>  <div>this is default04</div></app-content-more>

有条件的内容投影-ng-template, ng-container, directive 等来配合实现

单个条件的内容投影

eg: 假设现在有一个人员列表，当某个人的money大于200的时候，额外添加组件中模板定义的内容

定义一个 appChildRef 指令来配合 ng-template 获取模板

import { Directive, TemplateRef } from '@angular/core';@Directive({  selector: '[appChildRef]'})export class ChildRefDirective {  constructor(public templateRef: TemplateRef<any>) { }}

app-persons - html

<div class="list-item" *ngFor="let person of persons;">  <div>Name: {{ person.name }}</div>  <div>Money: {{ person.money }}</div>  <div *ngIf="person.money > 200">    <ng-container *ngIf="childRef" [ngTemplateOutlet]="childRef.templateRef"></ng-container>  </div></div>

app-persons - ts

import { Component, ContentChild, OnInit } from '@angular/core';import { ChildRefDirective } from '../../../../directives/child-ref.directive';@Component({  selector: 'app-persons',  templateUrl: './persons.component.html',  styleUrls: ['./persons.component.scss']})export class PersonsComponent impleme ['./form-unit.component.scss']})export class FormUnitComponent implements OnInit {  persons: { name: string; money: number; render?: string; }[] = [    { name: '杰克', money: 120, render: 'temp1' },    { name: '李莉', money: 210, render: 'temp2' },    { name: '张三', money: 170, render: 'temp3' },  ];  // @ContentChild(ChildRefDirective, { static: true }) childRef!: ChildRefDirective;  @ContentChildren(ChildRefDirective) childrenRef!: QueryList<ChildRefDirective>;  get tempRefs() {    const aObj: any = {};    this.childrenRef.forEach(template => {      const key: string = template.appChildRef;      aObj[key] = template;    })    return aObj;  }  constructor() { }  ngOnInit(): void { }}

使用

<app-persons>  <ng-template appChildRef="temp1" let-person let-index="i">    <div style="font-size: 14px; color: red;">{{index}}-{{person.name}}: this is temp1</div>  </ng-template>  <ng-template appChildRef="temp2" let-person let-index="i">    <div style="font-size: 14px; color: green;">{{index}}-{{person.name}}: this is temp2</div>  </ng-template>  <ng-template appChildRef="temp3" let-person let-index="i">    <div style="font-size: 14px; color: orange;">{{index}}-{{person.name}}: this is temp3</div>  </ng-template></app-persons>