Async/Await与Promise.all和.map函数无法正常工作 [英] Async/Await not working as expected with Promise.all and a .map function

问题描述

我正在使用大量的async个函数，但遇到了一个奇怪的问题.

I have a slew of async functions I'm using and I'm having a weird issue.

我的代码正常工作，如下所示:

My code, working, looks like:

async mainAsyncFunc (metadata) {
  let files = metadata.map(data => this.anotherAsyncFunc(data.url));
  return Promise.all(files);
}

anotherAsyncFunc函数如下:

  async anotherAsyncFunc (url) {
    return await axios({
      url,
    }).then(res => res.data)
      .catch(err => {
      throw err;
    });
  }

当我尝试向第一个函数(mainAsyncFunc)返回的内容追加更多数据时，出现了我的问题.我的想法是自然地在map中做到这一点，当一切都说完之后，修改它就像:

My issue comes when I try to append more data to what the first function (mainAsyncFunc) returns. My thoughts are to do that in the map, naturally, and when all is said and done, modified it looks like:

async mainAsyncFunc (metadata) {
    files = metadata.map(data => {
        return new Promise((resolve) => {
          let file = this.anotherAsyncFunc(data.download_url);
          let fileName = data.name;
          resolve({
            file,
            fileName
          });
        });
      });
    return Promise.all(files);
}

如果不清楚，我将像普通文件一样获取文件本身，并向其附加fileName，然后将该对象重新解析.

If it's not clear, I'm getting the file itself like normal, and appending a fileName to it, then resolving that object back.

由于某种原因，这将返回一个未决的Promise，而我希望它等待它们完成，然后以完整的文件和对象的名称返回.理解我在做什么的任何帮助将不胜感激.

For some reason, this is returning a pending Promise, whereas I would expect it to wait for them to be fulfilled and then returned as a complete file and name in an object. Any help understanding what I'm doing wrong would be greatly appreciated.

推荐答案

看起来您已经解决了问题，只需一点指针，就可以进一步简化代码，如下所示:

It looks like you've solved your issue, just as a bit of a pointer, you can further simplify your code as follows:

async anotherAsyncFunc (url) {
    return (await axios({ url })).data;
}

async mainAsyncFunc (metadata) {
    let files = metadata.map(async data => ({
        file: await this.anotherAsyncFunc(data.download_url),
        fileName: data.name
    }));

    return Promise.all(files);
}

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