用购物车创建商品时出现问题

Question

我在这里解决了一些问题，但是得到了以下消息：

Reference.update失败：第一个参数包含未定义的属性'购物车。-LRvqLfzwv9q9OMfW23K.items.-LPa0C_lNj2VAe1xLF5S.product.title'

未创建根。

export class ShoppingCartService {

  constructor(private db: AngularFireDatabase) { }

  private create() {
    return this.db.list('/shopping-carts').push({
      dateCreated: new Date().getTime()
    });
  }

  private getCart(cartId: string) {
    return this.db.object('/shopping-carts/' + cartId);
  }

  getItem(cartId: string, productId: string) {
    return this.db.object('/shopping-carts/' + cartId + '/items/' + productId);
  }

  private async getOrCreateCartId() {
    const cartId = localStorage.getItem('cartId');
    if (cartId) { return cartId; }

    const result = await this.create();
    localStorage.setItem('cartId', result.key);
    return result.key;

  }

  async addToCart(product) {
    const cartId = await this.getOrCreateCartId();
    const item$ = this.getItem(cartId, product.key);
    item$.snapshotChanges().take(1).subscribe((item: any) => {
      if (item.payload.exists()) {
        item$.update({ product: product, quantity: item.payload.val().quantity + 1});
      } else {
          item$.update({ product: {
            title: product.title,
            price: product.price,
            category: product.category,
            imageUrl: product.imageUrl,

          }, quantity: 1} );
        }
    });

  

}

Answer 1

尝试更改此行：

  

item $ .update（{product：product，quanity：（item.payload.val.quanity +   1}）

与

  

item $ .update（{product：product，quanity：（item.payload.val.quanity + 1）}）

更新对象时，您缺少'）'。

Answer 2

最后，我解决了这个问题，我想与所有人共享

export class ShoppingCartService {

  constructor(private db: AngularFireDatabase) { }

  private create() {
    return this.db.list('/shopping-carts').push({
      dateCreated: new Date().getTime()
    });
  }

  private getCart(cartId: string) {
    return this.db.object('/shopping-carts/' + cartId);
  }

  getItem(cartId: string, productId: string) {
    return this.db.object('/shopping-carts/' + cartId + '/items/' + productId);
  }

  private async getOrCreateCartId() {
    const cartId = localStorage.getItem('cartId');
    if (cartId) { return cartId; }

    const result = await this.create();
    localStorage.setItem('cartId', result.key);
    return result.key;

  }

  async addToCart(product) {
    const cartId = await this.getOrCreateCartId();
    const item$ = this.getItem(cartId, product.key);
    console.log(item$);

    item$.snapshotChanges().take(1).subscribe((item: any) => {
      if (item.payload.exists()) {
        item$.update({quantity: item.payload.val().quantity + 1 });
      } else {
        item$.update({
          product: {
            title: product.payload.val().title,
            price:  product.payload.val().price,
            category:  product.payload.val().category,
            imageUrl:  product.payload.val().imageUrl,

          }, quantity: 1
        });
      }
    });
  }
}