如何在 Angular 8 中捕获动态渲染组件输出？

Question

我想捕捉来自ViewChild 渲染组件的输出。在ngIf 触发后显示的 ViewChild 的内容。

这是我的模板代码：

<div *ngIf="isModalVisible" class="modal" tabindex="-1" role="dialog">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <!-- ... -->
      </div>
      <div class="modal-body">
        <ng-template #dialogHost (saveModel)="setModel($event)"></ng-template>
      </div>
    </div>
  </div>
</div>

这是 TypeScript 文件：

import { ChangeDetectorRef, Component, ComponentFactoryResolver, Input, ViewChild, ViewContainerRef } from '@angular/core';
import { DialogContentItem } from 'src/app/models/dialog/content/dialog-content-item';

@Component({
  selector: 'app-dialog-preparator',
  templateUrl: './dialog-preparator.component.html',
  styleUrls: ['./dialog-preparator.component.css']
})
export class DialogPreparatorComponent {
  isModalVisible = false;
  @Input() dialogContent: DialogContentItem;
  @ViewChild('dialogHost', {static: false, read: ViewContainerRef}) dialogHost: ViewContainerRef;

  showModal() {
    this.isModalVisible = true;
    this.changeDetector.detectChanges();
    this.renderComponent();
  }

  renderComponent() {
    const componentFactory = this.componentFactoryResolver.resolveComponentFactory(this.dialogContent.component);

    this.dialogHost.clear();

    const componentRef = this.dialogHost.createComponent(componentFactory);
    (componentRef.instance as DialogContentInterface).data = this.dialogContent.data;
  }

  setModel(model: any) {
    // I need to emit the model
  }
}

这里是 ProcutCreateEditComponent：

<app-dialog-preparator [dialogContent]="userDialogContent"></app-dialog-preparator>

该组件的 TypeScript 代码：

import { Component } from '@angular/core';
import { UserCreateEditComponent } from 'src/app/components/user/user-create-edit.component';

@Component({
  selector: 'app-product-create-edit',
  templateUrl: './product-create-edit.component.html',
  styleUrls: ['./product-create-edit.component.scss']
})
export class ProductCreateEditComponent {
  // this could be any other component in my software
  userDialogContent: DialogContentItem = new DialogContentItem(UserCreateEditComponent, {});

  constructor() {}

  // ...
}

这里是 UserCreateEditComponent 的 TypeScript 代码：

import { Component, Output } from '@angular/core';

@Component({
  selector: 'app-user-create-edit',
  templateUrl: './user-create-edit.component.html',
  styleUrls: ['./user-create-edit.component.scss']
})
export class UserCreateEditComponent {
  @Output() saveModel: EventEmitter<T> = new EventEmitter();
  user = new User();

  constructor() {}

  save() {
    this.saveModel.emit(this.user);
  }
}

所以在 ProcutCreateEditComponent 中我创建了一个 UserCreateEditComponent 的实例并将这个实例传递给 DialogPreparatorComponent。 DialogPreparatorComponent 在对话框中显示 UserCreateEditComponent，然后单击保存按钮（在 UserCreateEditComponent 中），saveModel() 发送到 DialogPreparatorComponent。我想......但不是这个，我收到了这个错误消息：

Event binding saveModel not emitted by any directive on an embedded template.
Make sure that the event name is spelled correctly and all directives are
listed in the "@NgModule.declarations". ("
      </div>
      <div class="modal-body">
        <ng-template #dialogHost [ERROR ->](saveModel)="setModel($event)"></ng-template>
      </div>
    </div>

其实很好，因为ng-template 没有saveModel() 输出。

但是我怎样才能捕捉到 UserCreateEditComponent 的输出呢？

Answer 1

由于您在代码中创建组件，因此您无法在模板中添加事件处理程序，您必须在创建组件时也将其添加到组件代码中。

例如，您可以更改渲染组件方法以添加订阅。

renderComponent() {
  const componentFactory = this.componentFactoryResolver.resolveComponentFactory(this.dialogContent.component);

  this.dialogHost.clear();

  const componentRef = this.dialogHost.createComponent(componentFactory);
  (componentRef.instance as DialogContentInterface).data = this.dialogContent.data;
  (componentRef.instance as DialogContentInterface).saveModel.subscribe((model) => this.setModel(model));
}

我希望我正确理解了您的模型，并且您在此处创建的组件是具有输出属性的组件。

确保在销毁动态组件时也取消订阅，这样您就不会因为剩余订阅而导致内存泄漏。