angular 2更新对象数组在可观察的订阅中

Question

我正在尝试更新observable subscribe方法中的对象数组。但它并没有像预期的那样更新。 我的实现如下。 Compoent.ts

constructor(private shopHomeService: ShopHomeService) {

    this.shopHomeService.shopItemChanged.subscribe(
      (item) => {
        if (item) {
          this.items = shopHomeService.getShopItems();
          if (this.items.length > 0) {
            const findItem = this.items.find(shopItem => shopItem.Id === item.Id);
            if (findItem) {
              findItem.OrderQuantity = findItem.OrderQuantity + 1;
            } else {
              this.items.push(item);
            }
          } else {
            this.items.push(item);
          }
          this.items = this.items.slice();
          shopHomeService.ShopItems = this.items;
          this.shopItems = [];
          this.shopItems = this.items;
        }

      }
    );
  }

Service.ts

import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';

@Injectable()

    export class ShopHomeService {
      private shopItems = [];
      private shopItem: any;
      shopItemChanged = new BehaviorSubject<any>(this.shopItem);

      constructor() { }

      getShopItems() {
        console.log(this.shopItems);
        return this.shopItems;
      }

      set ShopItems(shopItems) {
        this.shopItems = shopItems;
        console.log(this.shopItems);
      }

      addShopItem(item) {
        item.OrderQuantity = 1;
        item.Discount = 0;
        item.DiscountPercentage = 0;
        this.shopItemChanged.next(item);
      }

      removeShopItem(item) {
        this.shopItems = this.shopItems.filter(element => element.Id !== item.Id);
        this.shopItemChanged.next(this.shopItems);
      }

    }

最初 OrderQuantity 属性在数组项的每个对象中设置为1。 当相同类型的对象添加到shopItems时，它将使OrderQuantity的值增加1.逻辑已经实现了上面的代码。但是当商店商品改变时，它总是给出具有 OrderQuantity = 1 的对象数组。 （ shopHomeService.getShopItems（）返回OrderQuantity = 1的数组列表，但当 shopHomeService.ShopItems 调用它时发送rderQuantity = 2）