angular內容投影詳解

阿新 • • 發佈：2021-12-23

單內容投影

利用ng-content來實現

<!-- 元件 - app-content-single -->
<div>
  <h2>標題</h2>
  <!-- 投影內容顯示位置 -->
  <ng-content></ng-content>
</div>
<!-- 使用 -->
<app-content-single>
  <div>this is content</div>
</app-content-single>

多內容投影

利用ng-content來實現

<!-- 元件 - 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</diJQjlAWK 
v>
  <footer>this is footer</footer>
  <div>this is default04</div>
</app-content-more>

有條件的內容投影-ng-template,ng-container,directive 等來配合實現

單個條件的內容投影

eg: 假設現在有一個人員列表，當某個人的money大於200的時候，額外新增元件中模板定義的內容

定義一個 appChildRef 指令來配合 ng-template 獲取模板

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.s']
})
export class PersonsComponent implements OnInit {
  persons: { name: string; money: number; }[] = [
    { name: '傑克',money: 120 },{ name: '李莉',money: 210 },{ name: '張三',money: 170 },];
  @ContentChild(ChildRefDirective,{ static: true }) childRef!: ChildRefDirective;
  constructor() { }
  ngOnInit(): void { }
}

使用

<app-persons>
  <ng-template appChildRef>
    <div style="font-size: 14px; color: red;">this is child ref content</div>
  </ng-template>
</app-persons>

效果圖

多個條件內容投影

eg: 現在希望通過 persons 資料中的欄位進行繫結內嵌的模板來顯示

appChildRef 調整

import { Directive,Input,TemplateRef } from '@angular/core';
@Directive({
  selector: '[appChildRef]'
})
export class ChildRefDirective {
  // 接受定義模板名稱-通過這個名稱和 persons 中的render欄位對應進行顯示對應的模板內容
  @Input() appChildRef!: string;
  constructor(public templateRef: TemplateRef<any>) { }
}

app-persons - html

<div class="list-item" *ngFor="let person of persons;let i=index;">
  <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 *ngIf="person.render && tempRefs[person.render]">
    <!-- 配合 ngTemplateOutlet 指令給template傳遞當前person的資料 -->
    <ng-container *ngTemplateOutlet="tempRefs[person.renderhttp://www.cppcns.com].templateRef; context: { $implicit: person,i: i }"></ng-container>
  </div>
</div>

app-persons - ts

import { Component,ContentChildren,OnInit,QueryList } from '@angular/core';
import { ChildRefDirective } from '../../../../directives/child-ref.directive';
@Component({
  selector: 'app-form-unit',templateUrl: './form-unit.component.html',styleUrls: ['./form-unit.component.scss']
})
export class FormUnitComponent implements OnInit {
  persons: { name: string; money: number; render?: string; }[] = [
    { name: '傑克',money: 120,render: 'temp1' },money: 210,render: 'temp2' },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>
  <nJQjlAWKg-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-sizeJQjlAWK: 14px; color: orange;">{{index}}-{{person.name}}: this is temp3</div>
  </ng-template>
</app-persons>