RXJS 如何在嵌套订阅中优化 ForEach？

Question

我对 observables 还比较陌生，仍在学习，我需要一些帮助。我有一个包含一些广告系列的 slider ，对于每个广告系列，我都有一个制作人，我需要获取该制作人并将其设置为广告系列。

我知道在这里使用管道、合并和 MergeMap 可能是一些解决方案，但我似乎无法让它工作，有人对我有想法吗？

这是我目前拥有的。

  fetchCampaigns() {
    this.loading = true;
    this.campaignService
      .getCampaigns(
        this.campaignAmount,
        this.sorting,
        this.desc
      )
      .subscribe(
        campaignListDto => {
          this.campaigns = campaignListDto;
          this.campaigns.map(campaign => {
            this.producerService.getProducerByName(campaign.producer_name)
              .subscribe((producer) => {
                campaign.producer = producer
                campaign.producer_name
              })
            })
            this.loading = false; 
            this.fetchProducerMinPrices();
            this.fetchProducerTotalCampaigns();
        })
  };

Answer 1

尝试:

fetchCampaigns() {
  this.loading = true;
  this.campaignService.getCampaigns(this.campaignAmount,this.sorting,this.desc).pipe(
    switchMap(campaignListDto => forkJoin(campaignListDto.map(
      campaign => this.producerService.getProducerByName(campaign.producer_name).pipe(
        map(producer => ({ ...campaign, producer })),
      ),
    ))),
  ).subscribe(campaignListDtoExtended => {
    this.campaigns = campaignListDtoExtended;
    this.loading = false; 
    this.fetchProducerMinPrices();
    this.fetchProducerTotalCampaigns();
  });
}