Question

export class YoutubeService {

  getTrendingVideos(country) {
    let result = [];
    return axios.get('/').then(function(res){
      result = res.data.items;
      for (var i = 0; i < result.length; i++) {
        result[i] = {
          id: result[i].id,
          title: result[i].snippet.title,
          thumbnail: result[i].snippet.thumbnails.high.url,
          publishedAt: moment(result[i].snippet.publishedAt).fromNow()
        };
        result[i]= YoutubeService.getVideoDetails(result[i]).then(
            (video)=> 
              {
                  return video;
              }
        ); //result[i] is not getting resolved
        console.log(result[i]); // it returns Promise { <pending> }
      }
      return result;
    });

  }

  static getVideoDetails(video) {
    return axios.get('/').then(function(res) {
      let result = res.data;
      video.viewCount = result['items'][0].statistics.viewCount;
      video.likeCount = result['items'][0].statistics.likeCount;
      return video;
    });
  }
}

如何从'.then（）'内部为'result [i]'数组赋值。目前看来它是空的。返回的错误是Promise {{<pending>}。预先感谢。

Answer 1

Promise.all()将在传递的承诺数组解决后解决。

代码应收集getVideoDetails()做出的承诺，并返回执行这些请求的承诺...

  getTrendingVideos(country) {
    let result = [];
    let promises = [];
    return axios.get('/').then(function(res){
      result = res.data.items;
      for (var i = 0; i < result.length; i++) {
        result[i] = {
          id: result[i].id,
          title: result[i].snippet.title,
          thumbnail: result[i].snippet.thumbnails.high.url,
          publishedAt: moment(result[i].snippet.publishedAt).fromNow()
        };
        promises.push( YoutubeService.getVideoDetails(result[i]) )
      }
      return Promise.all(promises);
    });
  }

如何从内部在PROMISE之外分配值

1 个答案: