Firebase cloud function for file upload

I got a solution from the Firebase Support Team

So first thing:

var filePath = file.path + "/" + file.name;

we dont need the file.name since the file.path is full path of the file (including the file name).

So changed it to this instead:

var filePath = file.path;

Second, the function terminates before the asynchronous work in 'form.parse(...)' is completed. That means the actual file upload might still be in progress while the function execution has ended.

The fix for that is to wrap the form.parse(...) in a promise:

exports.uploadFile = functions.https.onRequest((req, res) => {
   var form = new formidable.IncomingForm();
   return new Promise((resolve, reject) => {
     form.parse(req, function(err, fields, files) {
       var file = files.fileToUpload;
       if(!file){
         reject("no file to upload, please choose a file.");
         return;
       }
       console.info("about to upload file as a json: " + file.type);
       var filePath = file.path;
       console.log('File path: ' + filePath);
 
       var bucket = gcs.bucket('bucket-name');
       return bucket.upload(filePath, {
           destination: file.name
       }).then(() => {
         resolve();  // Whole thing completed successfully.
       }).catch((err) => {
         reject('Failed to upload: ' + JSON.stringify(err));
       });
     });
   }).then(() => {
     res.status(200).send('Yay!');
     return null
   }).catch(err => {
     console.error('Error while parsing form: ' + err);
     res.status(500).send('Error while parsing form: ' + err);
   });
 });

Lastly, you may want to consider using the Cloud Storage for Firebase in uploading your file instead of Cloud functions. Cloud Storage for Firebase allows you to upload files directly to it, and would work much better:

1. It has access control
2. It has resumable uploads/downloads (great for poor connectivity)
3. It can accept files of any size without timeout-issues
4. If you want to trigger a Cloud Function on file upload even, you can do that and a lot more

I managed this by downloading the file to the tmp instead.

You will need:

const mkdirp = require('mkdirp-promise');

Then, inside onChange. I created tempLocalDir like so:

const LOCAL_TMP_FOLDER = '/tmp/';
const fileDir = (the name of the file); //whatever method you choose to do this
const tempLocalDir = `${LOCAL_TMP_FOLDER}${fileDir}`;

Then I use mkdirp to make the temp directory

return mkdirp(tempLocalDir).then(() => {
// Then Download file from bucket.
const bucket = gcs.bucket(object.bucket);
return bucket.file(filePath).download({
  destination: tempLocalFile
}).then(() => {
    console.log('The file has been downloaded to', tempLocalFile);
    //Here I have some code that converts images then returns the converted image
    //Then I use
    return bucket.upload((the converted image), {
        destination: (a file path in your database)
    }).then(() => {
        console.log('JPEG image uploaded to Storage at', filePath);
    })//You can perform more actions of end the promise here

I think my code achieves that you were trying to accomplish. I hope this helps; I can offer more code if necessary.