如何在不超过用户速率限制的情况下使用node.js向Google Drive API发出3千个请求？

Question

I am helping a friend which has the following problem.

He wants to have 3000 folders in google drive. For each one of them he will generate a QR code pointing to their URL. He will fill each folder with a photo people will take themselves on an event and people will then take home a small card with the QR code of their folder printed on it so they can see the photo home.

I made a small nodejs program using google's official nodejs client, and it works perfectly for one folder. Here's the code:

function listFiles(auth) {
  var fileMetadata = {
    'name' : "Folder",
    "mimeType" : "application/vnd.google-apps.folder"
  };
  var service = google.drive({version: 'v3', auth: auth});
    fileMetadata.name = "FOLDER"
      fileMetadata.name = "FOLDER"
      service.files.create({
        resource: fileMetadata,
        fields: "id, webViewLink, name"
        },function(err, file){
          if(err){
            console.log(err);
          }
          else{
            request("https://api.qrserver.com/v1/create-qr-code/?data="+file.webViewLink+"&size=256x256").pipe(fs.createWriteStream("qr"+file.name+".png"));
            console.log("Folder id: ", file.id, file.webViewLink);
            //datab.close();
          }
      });
}

Now, I'm pretty new to nodejs and its async nature. I don't know how to use the same code, if possible, to create 3000 folders. I tried using a for loop, but then i got Usage Rate Limit error codes (403). I then used a sleep function, but i still got a few 403 codes and the folders were not being named correctly.

Can anyone point me in the right direction? Thanks a lot

Answer 1

This should work for you, it will fire next Promise after previous is resolved.

function listFiles(auth, folder) {
    return new Promise(function (resolve, reject) {
        var fileMetadata = {
            'name' : folder,
            "mimeType" : "application/vnd.google-apps.folder"
        };
        var service = google.drive({version: 'v3', auth: auth});
        fileMetadata.name = 'FOLDER'
        service.files.create({
            resource: fileMetadata,
            fields: "id, webViewLink, name"
        },function(err, file){
            if(err){
                reject(err);
                console.log(err);
            }
            else{
                var response = request("https://api.qrserver.com/v1/create-qr-code/?data="+file.webViewLink+"&size=256x256");
                response.on('end', function () {
                    resolve();
                })
                response.pipe(fs.createWriteStream("qr"+file.name+".png"));
                console.log("Folder id: ", file.id, file.webViewLink);
                //datab.close();
            }
        });
    });

}

var folders = ['a', 'b','c'];
var promises = [];
folders.forEach(function (folder) {
    promises.push(function () {
        return listFiles(auth, folder);
    });
})
(new Promise(function (resolve, reject) {
    const final = promises.reduce(function (prevTask, current) {
        return prevTask.then(current).catch(reject);
    }, Promise.resolve());
    final.then(resolve).catch(reject);
})).then(function() {
    // all ok
}).catch(function (error) {
    // ups
});

If this is still too fast you can wrap resolve in setTimeout

setTimeout(function() {
    resolve();
}, 1000);