Angular4:HttpClient-连续许多请求 [英] Angular4: HttpClient - many requests in succession

问题描述

我有一个http get请求，以从提要中获取某些项目的列表. feed API需要一个页面参数，该参数限制为20.我想获取前60个参数，因此我需要发出3个请求

I have a http get request to get a list of some items from a feed. the feed API requires a page param, which is limited to 20. I would like to get first 60 instead, so I need to make 3 requests

requestOptions.params.set('page', 1);
this.http.get(environment.api+ '.feed.json', requestOptions)
requestOptions.params.set('page', 2);
this.http.get(environment.api+ '.feed.json', requestOptions)
requestOptions.params.set('page', 3);
this.http.get(environment.api+ '.feed.json', requestOptions)

处理它以获得有序列表的最佳方法是什么?我不太喜欢嵌套

what is the best way to deal with it to get an ordered list? I am not very fond of nesting

推荐答案

您的服务

getPage(page) {
  /*init requestOptions*/
  requestOptions.params.set('page', page);
  return this.http
     .get(environment.api+ '.feed.json', requestOptions)
     .map(/*map your object to the expected one*/)
     .catch(/*catch any http exception*/);
}

您在哪里致电服务

let allPages = [];

Observable.forkJoin(
  this.service.getPage(1);
  this.service.getPage(2);
  this.service.getPage(3);
).subscribe((respArray) =>{
   allPages = allPages.concat(respArray[0]);
   allPages = allPages.concat(respArray[1]);
   allPages = allPages.concat(respArray[2]);
});

Object.forkJoin将等待所有请求完成，然后您可以使用此结果构建一个列表；

Object.forkJoin will wait until all requests are completed and then you can build a single list with this results;

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