Der umgeschriebene Titel lautet: Übergeben Sie Daten von der Vorlage an die zugehörige Komponente, nicht an andere Komponenten

Question

Wie übergebe ich Vorlagendaten an verwandte Komponenten statt an untergeordnete oder übergeordnete Komponenten, ohne neue zu erstellen?

Mein Projekt.html

<div *ngFor="let item of items">
 <div *ngFor="let subItem of subItems">
  <div *ngIf="!item.value.length">
   <div class="cloth {{nextAvailableSubItem}}"></div>
  </div>
 </div>
</div>

my-item.component.ts

this.items = {one: ['redShirt'], two: [], three: [] four: ['whiteShirt', 'blackShirt']}
 this.subItems = ['redShirt', 'blueShirt', 'whiteShirt', 'blackShirt'];

filterItems(item, subItem){
 return nextAvailableSubItem //在redShirt之后应该返回whiteShirt以在模板中使用该值
    }

Answer 1

一种常见的方法是通过一个中间服务使用Observable来共享数据

如下所示

• 中间服务：

import { Injectable } from '@angular/core';
    import { BehaviorSubject, Observable } from 'rxjs';
    
    @Injectable({
      providedIn: 'root'
    })
    export class SharedDataService {
      private dataSource = new BehaviorSubject<any>('初始值');
      public data$: Observable<any> = this.dataSource.asObservable();
    
      updateData(newData: any): void {
        this.dataSource.next(newData);
      }
    }

• 第一个组件（数据发送者）：

import { Component } from '@angular/core';
import { SharedDataService } from './shared-data.service';

@Component({
  selector: 'app-first-component',
  template: `...`
})
export class FirstComponent {
  constructor(private sharedDataService: SharedDataService) {}

  updateSharedData(): void {
    this.sharedDataService.updateData('新值');
  }
}

• 第二个组件（数据消费者）：

import { Component, OnDestroy } from '@angular/core';
    import { SharedDataService } from './shared-data.service';
    import { Subscription } from 'rxjs';
    
    @Component({
      selector: 'app-second-component',
      template: `...`
    })
    export class SecondComponent implements OnDestroy {
      sharedData: any;
      private subscription: Subscription;
    
      constructor(private sharedDataService: SharedDataService) {
        this.subscription = this.sharedDataService.data$.subscribe(data => {
          this.sharedData = data;
          // 在这里消费数据
        });
      }
    
      ngOnDestroy(): void {
        this.subscription.unsubscribe();
      }
    }

不要忘记在消费者组件销毁时取消订阅，否则会导致内存泄漏。