Javascript/流变量未定义

Question

Here is my code. the variable file in the code

console.log(JSON.stringify(file));

is undefined.

const functions = require('firebase-functions');
const admin = require('firebase-admin');
const Buffer = require('buffer').Buffer;
const stream = require('stream');
exports.updateUserInfo = functions.https.onRequest(function(req, res){

    const uid = req.params.uid;
    const name = req.query.name;
    const gender = req.query.gender;
    const birthday = req.query.birthday;
    const base64Image = req.query.profileImage;
    let bufferStream = new stream.PassThrough();
    bufferStream.end(new Buffer.from(base64Image, 'base64'));
    let bucket = admin.storage().bucket();
    let file = bucket.file('user_images/' + uid + '/example.jpg');
    bufferStream.pipe(file.createWriteStream({
      metadata: {
        contentType: 'image/jpeg'
      }
    }))
    .on('error', error => {
      console.log("error", error);
    })
    .on('finish', (file) => {
      console.log(JSON.stringify(file));
    });
})

Answer 1

Stream event finish informs that operation is done, and passes no arguments. See https://nodejs.org/api/stream.html#stream_event_finish .

If you want use file object after operation is done:

let file = bucket.file('user_images/' + uid + '/example.jpg');
bufferStream.pipe(...)
.on('finish', () => {
  console.log(file);
});