How to read content of JSON file uploaded to google cloud storage using node js
There exists a convenient method:'download' to download a file into memory or to a local destination. You may use download method as follows:
const bucketName='bucket name here';
const fileName='file name here';
const storage = new Storage.Storage();
const file = storage.bucket(bucketName).file(fileName);
file.download(function(err, contents) {
console.log("file err: "+err);
console.log("file data: "+contents);
});
I was using the createWriteStream
method like the other answers but I had a problem with the output in that it randomly output invalid characters (�) for some characters in a string. I thought it could be some encoding problems.
I came up with my workaround that uses the download
method. The download
method returns a DownloadResponse
that contains an array of Buffer. We then use Buffer.toString()
method and give it an encoding of utf8
and parse the result with JSON.parse()
.
const downloadAsJson = async (bucket, path) => {
const file = await new Storage()
.bucket(bucket)
.file(path)
.download();
return JSON.parse(file[0].toString('utf8'));
}
I've used the following code to read a json file from Cloud Storage:
'use strict';
const Storage = require('@google-cloud/storage');
const storage = Storage();
exports.readFile = (req, res) => {
console.log('Reading File');
var archivo = storage.bucket('your-bucket').file('your-JSON-file').createReadStream();
console.log('Concat Data');
var buf = '';
archivo.on('data', function(d) {
buf += d;
}).on('end', function() {
console.log(buf);
console.log("End");
res.send(buf);
});
};
I'm reading from a stream and concat all the data within the file to the buf variable.
Hope it helps.
UPDATE
To read multiple files:
'use strict';
const {Storage} = require('@google-cloud/storage');
const storage = new Storage();
listFiles();
async function listFiles() {
const bucketName = 'your-bucket'
console.log('Listing objects in a Bucket');
const [files] = await storage.bucket(bucketName).getFiles();
files.forEach(file => {
console.log('Reading: '+file.name);
var archivo = file.createReadStream();
console.log('Concat Data');
var buf = '';
archivo.on('data', function(d) {
buf += d;
}).on('end', function() {
console.log(buf);
console.log("End");
});
});
};