javascript - 如何从 promise.all 获得被拒绝的 promise ？

Question

我编写了以下代码，用于在 promises 的帮助下在服务器上异步上传文件。我们知道一旦任何一个 promise 失败，promise.all 就会失败。所以，我想知道哪个 promise 实际上失败了，在我的例子中， promise 失败的文件名。我正在尝试 console.log(e1) 但它没有给我有关失败 promise 的信息。任何人都可以帮我做吗？

uploadFilesAndSendStatus(stateType, notes, estimate, visibleToCustomer = null)
  {
    let filesPromise = Promise.resolve([]);

    const promises = this.state.files_to_upload.map((file) => {
      return this.uploadFilesOnServer(file);
    });

    filesPromise = Promise.all(promises).then((results) => {

      return [].concat(...results);
    }).catch((e1) =>{
      console.log(e1);
      this.setState({
         serverActionPending: false,
         serverActionComplete: false,
         file_upload_try_again: true,
      });
    });
}  

UploadFilesOnServer 代码是:

uploadFilesOnServer(file) {
    let files=[];
    let file_id='';
    const image=file;
    const promise = getAttachmentUploadURL(this.props.task.id)
    .then((imageUrlResponse) => {
      const data = new FormData();

      data.append('file-0', image);

      const { upload_url }  = JSON.parse(imageUrlResponse);

      return uploadAttachment(upload_url, data);
    })
    .then ((updateImageResponse) => {
      file_id= JSON.parse(updateImageResponse);

      files.push(file_id);

      return files;
    });

    return promise;
  }

Answer 1

您可以将该信息添加到错误对象中:

const promises = this.state.files_to_upload.map((file, i) => {
  return this.uploadFilesOnServer(file).catch(err => {
    const e = new Error("upload failed");
    e.index = i;
    e.filename = file
    throw e;
  });
});

const filesPromise = Promise.all(promises).then(res => [].concat(...res)).catch(e1 => {
  console.log(e1);
  …
});