How to stream file as download on Loopback 4? - node.js

Question

I'm trying to create a system that would read a file from another site and serve this as a file download to the user. The file size could vary from Mbs to Gbs.
I have have already created a proof of concept using vanilla nodejs.
const app = express();
app.get('/', (req, res) => {
res.setHeader('Content-disposition', 'attachment; filename=FILENAME');
res.setHeader('Content-type', 'application/octet-stream');
http.get('URL_TO_FILE', data => {
data.pipe(res);
});
});
I would like to do this using loopback 4. Is this possible? Thanks!

Answer 1

You can do this easily with nodejs request and using the loopback 4 controllers.
You need to import this packages:
var request = require('request');
var fs = require('fs');
And put this code in the endpoint method:
#get('/getImage')
async retrieveImage(): Promise<any> {
let file = fs.createWriteStream(__dirname + `/file.jpg`);
console.log('the file is here: ' + file.path);
return await new Promise((resolve, reject) => {
request({
url: 'URL_TO_FILE',
headers: {
'Content-disposition': 'attachment; filename=FILENAME',
'Content-type': 'application/octet-stream',
},
gzip: true,
})
.pipe(file)
.on('finish', () => {
console.log(`The file is finished downloading.`);
resolve();
})
.on('error', (error: any) => {
reject(error);
})
}).catch(error => {
console.log(`something happened: ${error}`)
});
}
From this you need to go to this url:
http://localhost:3000/getImage
And the file would be in your controllers folder with the "file.jpg" name.