Improving the JSON file upload structure – Open Event Web app

Open Event Web app generator also allows user to upload JSON file for the event data other than the API endpoint. The generator used the socket connection ID to uniquely identify uploaded files on the server which worked good for a single socket connection but failed for multiple due to overlap of connection IDs which resulted in crashing of web app. The problem is fixed by providing a unique ID to every file uploaded on the server and creating a separate field for uploaded file ID in the request body.

How to add listener for file upload?

A listener for socket ‘file’ event is added in the file app.js, which is triggered when the event namely file is emitted by the socket. The file ID kept unique by introducing a counter for number of files uploaded on the server till now and incrementing the counter subsequently for every new file.

ss(socket).on('file', function(stream, file) {
 generator.startZipUpload(count, socket);
 filename = path.join(__dirname, '..', 'uploads/connection-' +    count.toString()) + '/';
 count += 1;


The procedure named startZipUpload in generator.js is executed when the zip file upload starts which further calls the helper function to make uploads directory on the server.

exports.startZipUpload = function(id, socket) {
 console.log('========================ZIP UPLOAD START\n\n');
 distHelper.makeUploadsDir(id, socket);

Creating uploads directory

Uploads directory is created in the root directory using the file system interfaces, the ID passed as parameter ensures that the file names do not overlap.

makeUploadsDir: function(id, socket) {
 fs.mkdirpSync(uploadsPath + '/connection-' + id.toString());
 socket.emit('uploadsId', id);

Embedding uploads ID with the data

After the successful creation of uploads directory and the file, the socket emits the ID of uploaded file through the event uploadsID. The value of ID thus received is embedded in the object namely data along with the other entries in the form.

socket.on('uploadsId', function(data) {
 initialValue = data;

function getData(initValue) {
 const data = initValue;
 const formData = $('#form').serializeArray();

 formData.forEach(function(field) {
   if ( === 'email') { = field.value;
   if ( === 'apiVersion') {
     data.apiVersion = field.value;


Tags:  GsoC’18, Fossasia, Eventyay, Open Event Web App, JSON file upload