详解Angular 自定义结构指令

import { Component, TemplateRef, ViewContainerRef, ViewChild,
 AfterViewInit } from '@angular/core';
@Component({
 selector: 'app-code404',
 template: `
 <!-- 这里使用一个模板变量，在组件中使用@ViewChild装饰器获取模板元素-->
  <ng-template #tpl>
   Big Keriy !
  </ng-template>
 `,
})
export class Code404Component implements AfterViewInit{

 // @ViewChild 装饰器获取模板元素
 @ViewChild('tpl')
 tplRef: TemplateRef<any>;
 constructor(private vcRef: ViewContainerRef) {}
 ngAfterViewInit() {

  // 使用ViewContainerRef对象的createEmbeddedView方法创建内嵌视图。
  this.vcRef.createEmbeddedView(this.tplRef);
 } }

import { Component } from '@angular/core';
 @Component({
  selector: 'app-code404',
  template: `
   <ng-template #stpl>
    Hello, Semlinker!
   </ng-template>
   <ng-template #atpl>
    Big Keriy !
   </ng-template>
   <div [ngTemplateOutlet]="atpl"></div>
   <div [ngTemplateOutlet]="stpl"></div>
`, })
 export class Code404Component { }

import { Component, TemplateRef, ViewContainerRef, ViewChild,
 AfterViewInit } from '@angular/core';
@Component({
 selector: 'app-code404',
 template: `
  <!-- 这里的messagey映射到下面context中message 再使用插值表达式的方式显示message的值 -->
  <ng-template #stpl let-message="message">
   <p>{{message}}</p>
  </ng-template>
  <!-- 这里的messagey映射到下面context中message , let-msg是一种与语法糖的方式变量名是msg-->
  <ng-template #atpl let-msg="message">
   <p>{{msg}}</p>
  </ng-template>
  <!-- 若不指定变量值那么将显示 $implicit 的值-->
  <ng-template #otpl let-msg>
   <p>{{msg}}</p>
  </ng-template>
  <div [ngTemplateOutlet]="atpl"
     // 这里ngOutletContext绑定的是context对象
     [ngOutletContext]="context">
  </div>
  <div [ngTemplateOutlet]="stpl"
     [ngOutletContext]="context">
  </div>
  <div [ngTemplateOutlet]="otpl"
     [ngOutletContext]="context">
  </div>
 `,
})
export class Code404Component implements AfterViewInit{
 @ViewChild('tpl')
 tplRef: TemplateRef<any>;
 constructor(private vcRef: ViewContainerRef) {}
 ngAfterViewInit() {
  this.vcRef.createEmbeddedView(this.tplRef);
 }
 context = { message: 'Hello ngOutletContext!',
  $implicit: 'great, Semlinker!' };
  // 这里的$implicit是固定写法
}

 @Component({
  selector: 'alert-success',
  template: `
   <p>Alert success</p>
  `,
 })
 export class AlertSuccessComponent { }
 @Component({
  selector: 'alert-danger',
  template: `
   <p>Alert danger</p>
  `,
 })
 export class AlertDangerComponent { }
 @Component({
  selector: 'my-app',
  template: `
   <h1>Angular version 4</h1>
   <ng-container *ngComponentOutlet="alert"></ng-container>
   <button (click)="changeComponent()">Change component</button>
 `, })
 export class AppComponent {
   alert = AlertSuccessComponent;
  changeComponent() {
   this.alert = AlertDangerComponent;
 } 
}

// app.module.ts
@NgModule({
  // ...
  declarations: [
   AppComponent,
   SignUpComponent,
   AlertSuccessComponent,
   AlertDangerComponent
  ],
  entryComponents: [    // 这里面写指令中呀用到的组件
   AlertSuccessComponent,
   AlertDangerComponent
],
// ...
})

<!-- 简单语法 -->
<ng-container *ngComponentOutlet="componentTypeExpression"></ng-container>

<!-- 完整语法 -->
<ng-container *ngComponentOutlet="componentTypeExpression;
   injector: injectorExpression;
   content: contentNodesExpression;">
</ng-container>

// ...
@Component({
 selector: 'ng-component-outlet-complete-example',
 template: `
  <ng-container *ngComponentOutlet="CompleteComponent; 
                   injector: myInjector; 
                   content: myContent"></ng-container>`
})
class NgTemplateOutletCompleteExample {
 // This field is necessary to expose CompleteComponent to the template.
 CompleteComponent = CompleteComponent;
 myInjector: Injector;

 myContent = [[document.createTextNode('Ahoj')], [document.createTextNode('Svet')]];

 constructor(injector: Injector) {
  this.myInjector = ReflectiveInjector.resolveAndCreate([Greeter], injector);
 }
}

// uless.directive.ts

import { Directive, Input, TemplateRef, ViewContainerRef } from '@angular/core';
 @Directive({
   selector: '[exeUnless]'
 })
 export class UnlessDirective {
   @Input('exeUnless')
   set condition(newCondition: boolean) { // set condition
     if (!newCondition) {
       this.viewContainer.createEmbeddedView(this.templateRef);
     } else {
       this.viewContainer.clear();
     } 
   }
   constructor(private templateRef: TemplateRef<any>,
     private viewContainer: ViewContainerRef) {
   } 
 }


 import { Component } from '@angular/core';
 @Component({
  selector: 'app-root',
  template: `
   <h2 *exeUnless="condition">Hello, Semlinker!</h2>
  `,
 })
 export class AppComponent {
  condition: boolean = false;
 }


 // app.component.ts

 import { Component } from '@angular/core';
 @Component({
  selector: 'app-root',
  template: `
   <h2 *exeUnless="condition">Hello, Semlinker!</h2>
  `,
 })
 export class AppComponent {
  condition: boolean = false;
 }