The rewritten title is: Pass data from template to related component, not to other components

Question

How to pass template data to related components instead of child or parent components without creating new components?

My project.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

A common approach is to use Observable to share data through an intermediate service

As follows

• Intermediate service:

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);
      }
    }

• First component (data sender):

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');
  }
}

• Second component (data consumer):

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();
      }
    }

Don't forget to unsubscribe when the consumer component is destroyed, otherwise it will cause a memory leak.