在 subscribe 中调用 subscribe 是个好方法吗? [英] Is it good way to call subscribe inside subscribe?

问题描述

我需要将三个数据从三个不同的 API 传递给一个函数:

I need to pass three data to one function from three different APIs:

this.service.service1().subscribe( res1 => {
  this.service.service1().subscribe( res2 => {
    this.service.service1().subscribe( res3 => {
      this.funcA(res1, res2, res3);
  });
  });
});

在订阅内订阅是一个好习惯吗?

Is it a good practice to subscribe inside a subscribe?

推荐答案

正确的方法是以某种方式组合各种 observable 然后订阅整个流程——如何组合它们将取决于您的确切需求.

The correct way is to compose the various observables in some manner then subscribe to the overall flow — how you compose them will depend on your exact requirements.

如果您可以并行执行所有操作:

If you can do them all in parallel:

forkJoin(
  this.service.service1(), this.service.service2(), this.service.service3()
).subscribe((res) => {
  this.funcA(res[0], res[1], res[2]);
});

如果每个都依赖于前一个的结果，则可以使用mergeMap(以前称为flatMap)或switchMap:

If each depends on the result of the previous, you can use mergeMap (formerly known as flatMap) or switchMap:

this.service.service1().pipe(
  mergeMap((res1) => this.service.service2(res1)),
  mergeMap((res2) => this.service.service3(res2))
).subscribe((res3) => {
  // Do something with res3.
});

...等等.有许多操作符可以组成 observables 以覆盖许多不同的场景.

... and so on. There are many operators to compose observables to cover lots of different scenarios.

这篇关于在 subscribe 中调用 subscribe 是个好方法吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！