Metamask popup on Server side Express js

+1 vote
So I have this problem when i used "window.web3.currentProvider" on my controller in express js, which i got an error say "window is undefined". And i know the "window" is not to work on server side.

Here is my code : (to post upload file), that works just fine, but i need my Metamask to popup so it can confirm the transaction and im still using TESTRPC. So is there any solution for me? Thank you~

exports.postUploadFile = (req, res, next) => {

var ethereumURI = req.body.ethereumURI;

var abi = JSON.parse(req.body.abi);

var contractAddress = req.body.contractAddress;

let web3 = new Web3();

web3.setProvider(new web3.providers.HttpProvider(ethereumURI));

//define default account[0]

const address = web3.eth.accounts[0];

const fileTitle = req.body.fileTitle;

const description = req.body.description;

const file = req.file;

const fileUrl = file.path;

const fileName = file.filename;

const submitAt = moment(new Date('DD-MM-YYYY, HH:mm:ss');

const newReportFile = fs.readFileSync(req.file.path);

const encodingBase64 = newReportFile.toString('base64');

const encodingMD5 = crypto.createHash('md5').update(newReportFile).digest('HEX');

if (!web3.isConnected()) {

throw new Error('unable to connect to ethereum node at ' + ethereumURI);

} else {

console.log('connected to ethereum node at ' + ethereumURI);

let accounts = web3.eth.accounts[0];

console.log('account : ' + accounts);


var DFRVerificationContract = web3.eth.contract(abi);

var Report =;

console.log('Report has been sent!');

const bapFiles = new BapFiles({

fileName: fileName,

submitAt: submitAt,

fileTitle: fileTitle,

description: description,

fileUrl: fileUrl,

userId: req.user

}); = encodingBase64;

bapFiles.reportFile.contentType = req.file.mimetype;

bapFiles.reportFileHash = encodingMD5;

if (req.session.isLoggedIn) { => {


var id = result._id;

console.log('ID:', id);

var fileReport = {

filePath: fileUrl,

fileName: fileName,

fileHash: encodingMD5,

description: description,

createdAt: submitAt


var reportObject = JSON.stringify(fileReport);

var reportWithoutQuotes = reportObject.toString().replace(/"/g, "");

var idObject = JSON.stringify(id);

var IDWithoutQuotes = idObject.toString().replace(/"/g, "");



console.log('address: ', address);


Report.uploadReport(IDWithoutQuotes, fileTitle, reportWithoutQuotes, address, {

from: address,

gas: '4700000'


console.log('Success Upload File!');


}).catch(err => {



} else {

console.log('Fail to Upload File');

console.log('User not Logged In. Please Login first!');

return res.redirect('/');


Jul 15, 2019 in Blockchain by Dzaky
• 130 points

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