Angular 中连续 HTTP 请求的动态数量 [英] Dynamic amount of sequential HTTP requests in Angular

问题描述

这是我在这里的第一个问题，如果不够详细，请见谅.

我希望按顺序发出动态数量的请求(可能很多)以获取数据，

我需要从每个请求中收集这些数据，并在最后一个请求结束时作为最终的 observable 返回.

我尝试使用 forkJoin 来组合请求，虽然，这并没有按顺序创建每个请求，然后还有 concat，它在每个请求之后发出和观察.

解决方案

您想要:

• 发出任意数量的连续 HTTP 请求(我假设基于某个数组)
• 返回结果数组

我会在这里将 concat 与 toArray 结合使用.concat 将按顺序运行请求，当所有响应都可用时 toArray 将发出一个数组.

//一些动态数组常量源 = [ 1, 2, 3, 4, 5 ];const observables = source.map(x => this.http.get('some url'));连接(...可观察的).管道(toArray()). 订阅(响应 => {控制台日志(响应)；//结果数组});

演示:https://stackblitz.com/edit/angular-s1fdxj

This is my first question here, sorry if it isn't detailed enough.

I am looking to make a dynamic amount of requests sequentially (could be a lot) to get data,

I would need this data to be collected from each request and returned as a final observable at the end of the last request.

I have attempted to use forkJoin to combine the requests, although, this does not make each request sequentially and then also concat, which emits and observable after each request.

解决方案

You want to:

• Make an arbitrary number of sequential HTTP requests (based on some array, I assume)
• Return an array of results

I would use concat in conjunction with toArray here. concat will run the requests sequentially, and toArray will emit an array when all responses are available.

// some dynamic array
const source = [ 1, 2, 3, 4, 5 ];

const observables = source.map(x => this.http.get('some url'));
concat(
  ...observables
).pipe(
  toArray()
).subscribe(responses => {
  console.log(responses);
  // array of results
});

DEMO: https://stackblitz.com/edit/angular-s1fdxj

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