使用列表数据为 drive.files.export Google Drive API V3 使用 Nodejs 定义下载参数

Question

My app can successfully list and download (export text/plain) a file, from Google Drive to my local hard drive, using separate functions listFiles() & downloadFile() (extensively using code from Nodejs Quickstart

I am trying to combine this code into a function that will download (export text/plain) of all files listed in the folder.

At this point my file and path references are 'hard coded' in for testing (one file/one path)

So I am trying to understand how any modified listFiles() code could loop through the available list of files and provide the next available fileId as a reference for the downloadFiles() code. I also wanted to provide the matching fileName for path building.

In my listFiles() I cannot seem to find much information on parsing the returned promise data stream. So I've just got a dumb version going. Which can only download 1 file. (this is my understanding of the code)

/**
 * Lists names and IDs of pageSize number of files (using query to define folder of files)
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
 function listFiles(auth) {
  const drive = google.drive({version: 'v3', auth});

    drive.files.list({
        corpora: 'user',  
        pageSize: 1,
        // files in a parent folder (drive>ocrTarget ID) that have not been trashed  
        q: `'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' in parents and trashed=false`,    
        fields: 'nextPageToken, files(id, name)',
      }, (err, res) => {
        if (err) return console.log('The API returned an error: ' + err);
        const files = res.data.files;
        if (files.length) {
          files.map((file) => {
            console.log(file);  
          });
        } else {
          console.log('No files found.');
        }
      });
    }

Output

PS C:\Users\blah\blah\gDriveDev> node . myNodejsScript
{
  id: 'xxxx file id of only file that could be listed with PageSize: 1 xxxxx',
  name: 'Copy of 31832_226140__0001-00007'
}

I have gone through Google Drive for Developers Drive API (V3) docs (Guides/Reference) Which, cover request parameters. However I want to manipulate the data type/structure of output. eg walk the file list and parse the fileId.

(i) Before I got my download code working properly I was creating metadata files of a JSON layout type. Now I have no idea how I did this. They were saved according to my file/path settings like this:.

{
 "kind": "drive#file",
 "id": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
 "name": "atest.txt",
 "mimeType": "text/plain"
}

(ii) During experiments, running working code, I found that files.length has a value that equals the number of files listed in the available PageSize:

(iii) For files.map((file) it looked like I was dealing with a Map object MDN Map Reference But error messages in my test code showed that it was not.

(iv) I have seen the following type of code used for accessing parameters:

let data = 'Name,URL\n';

res.data.files.map(entry => {
  const { name, webViewLink } = entry;
  data += `${name},${webViewLink}\n`;
});

But I don't have the knowledge to interpret this in order to evaluate it for my situation.

If anyone can make a suggestion, for my situation, it would be appreciated.

-------------------- [Added to question] --------------------

To summarize I understand from the following:

const files = res.data.files;
    if (files.length) {
       files.map((file) => {

• length property is the number of files
• files produces list of length x length (x lists of x files)
• file produces a list of the files (id, name)

How do I index these results? Do I have to read each of the file details from the list into an array?

Some examples of output here:

console.log(Object.keys(file)); // a list of file key types

output

[ 'id', 'name' ]

and

console.log(file);

eg

    {
  id: 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
  name: 'Copy of 31832_226140__0001-00007'
}

But the keys are not numbered. So there is no numerical reference (index) available.

My aim: read the full list of file names available and supply these for each file to be downloaded.

Answer 1

You can use a forEach() loop with an index

Sample:

const files = res.data.files;
var ids = [];
if (files.length) {
    files.forEach(function (file, i) {
        ids[i]= file.id;
    })
}