RxJS：forkJoin 延迟似乎不适用于超过 1 个调用

Question

我有两个 http 调用，我需要延迟第二个调用或等待第一个调用完成，我添加了一个延迟，但第二个调用总是先执行。

ngOnInit

 forkJoin({
      getProductDetails:  this.getProductDetails(),
      getRelatedProducts: this.getRelatedProducts().pipe(delay(1000)) }).subscribe(res => {
        this.productDetailsData = res.getProductDetails;
        this.productsRelated = res.getRelatedProducts;
      }, err =>{
        // this.loader.hide();
      });
  }

获取产品详情

 getProductDetails(): Observable < any > {

    var queryString = `?productId=${this.productId}`;

    return this.marketCommunication.productDetails(queryString)
      .pipe(
        map((res) => {
          this.productCategoryId = res.productCategoryId

          return res
        }),
        catchError((err) => {
          throw err;
        })
      )

  }

getRelatedProducts

getRelatedProducts(): Observable < any > {

    console.log( this.productCategoryId) // -> returns null

    var queryString = `?productCategoryId=${this.productCategoryId}&take=&skip=`;

    return this.marketCommunication.publishedProductsByFilters(queryString)
      .pipe(
       map((res) => {
          return res
        }),
        catchError((err) => {
          throw err;
        })
      )


  }

Answer 1

你需要改用switchMap来确保它们一个接一个地执行：

this.getProductDetails().pipe(
  // now we have result of the first request and executing 2nd one.
  switchMap(getProductDetails => this.getRelatedProducts().pipe(

    // merging results together.
    map(getRelatedProducts => ({
      getProductDetails,
      getRelatedProducts,
    })),
  )),
).subscribe(res => {
  this.productDetailsData = res.getProductDetails;
  this.productsRelated = res.getRelatedProducts;
});

RxJS：forkJoin 延迟似乎不适用于超过 1 个调用

RxJS: forkJoin delay seems not working on more than 1 call

rxjs

angular

angular9