Question

import {Observable} from '@reactivex/rxjs'

// This is a fake API polling, this data is in reality coming from
// the server
const fakePoll$ = Observable.from([
  {
    status: 'initialized',
    data: {...},
  },
  {
    status: 'progress',
    data: {...},
  },
  {
    status: 'progress',
    data: {...},
  },
  {
    status: 'progress',
    data: {...},
  },
  {
    status: 'completed',
    data: {...},
  },
  ...
  {
    status: 'completed',
    data: {...},
  },
])

fakePoll$
  .takeWhile(x => x.status != 'completed')
  .subscribe(x => console.log(x))

此代码段会返回所有进度和初始化状态：

initialized
progress
progress
progress

但我需要让第一次完成也像takeWhile但包容性。

Answer 1

你可以考虑像这里一样添加它，如果这就是你所需要的：

Rx.Observable.concat(fakePoll$
  .takeWhile(x => x != 'completed'), Rx.Observable.from('completed'))
  .subscribe(x => console.log(x))

Answer 2

我相信你必须在使用api时使用repeat，假设它是一个承诺返回呼叫。我这样做了 Server Polling //代码在这里

angular.module('rxApp', ['rx'])
  .controller('AppCtrl', function($scope, $http, rx) {
    function getRandom(){
       return Math.floor(Math.random() * (10 - 1)) + 1;
    }

    function getResults(){
       console.log("returning promise");
       return $http({
          url: "https://en.wikipedia.org/w/api.php?&callback=JSON_CALLBACK",
          method: "jsonp",
          params: {
            action: "opensearch",
            search: 'eclipse',
            format: "json"
          }
        });
    }
    var toBeRepeated =  rx.Observable
    .fromPromise(getResults).repeat()
    .map(response => { console.log(response); return response.data[1]; })
    .map(results => {
        var rs = results[getRandom()];
        console.log(rs);
        return rs;
    });             

    var source = toBeRepeated.takeWhile(rs => rs.indexOf('play') === -1);
        source.subscribe(function(item){
        console.log("item:"+ item);
    },err => { console.log(err); },completed => {console.log("completed :" + completed);} );
});

希望这有帮助。

Rxjs：轮询数据直到满足谓词

2 个答案: