Download file with NodeJS - angularjs

Question

I am creating a csv file with node js and now want to download it to user's browser's default download location. We are using seneca with nodejs and csv file is getting saved on the server. Now when use will click export on the front end which angular based, node will create a csv and download that to user machine. How can we achieve this?

Answer 1

It is possible to download dynamic files generated with Node.js to the browser's default download location. There are many posts outlining how to retrieve static files from the server using the Express helper res.download(). Specific to your question there is a way to achieve what you are asking.
With interpretation of your question the following process is followed:
User generated data is sent to the server for processing when a user clicks export.
Node processes the data and generates a file that is to be downloaded without a second user interaction (user clicks Export and the file is downloaded).
Client
//Export button
$("#exportBtn").click(function () {
//Code to generate data for the CSV and save it to the src variable
var src = csvData;
//Send the CSV data to Node for processing and file generation.
$.post("http://localhost:3000/submitcsv", { csv: src }, function (data) {
//Check the returned file name in data - this check depends on your needs; ie: regex
if (data) {
//request the file that is to be downloaded to the client. Optionally use $window.open()
window.location.href = "http://localhost:3000/app/" + data;
}
});
});
Server
//Post data from the client
app.post('/submitcsv', function (req, res) {
var async = require('async');
var fs = require('fs');
var path = require('path');
var csvData = req.body.csv;
function processCSV(callback) {
//Code to create the csv file and a uniqueIdentifier
callback();
}
function finalize() {
//Save the CSV to the server. This is a specific location on the server in /app.
//You can use Express.static paths that suit your setup.
fs.writeFile('./app/temp/csvFile' + uniqueIdentifier + '.csv', buf, function (err) {
if (err) {
console.log(err);
res.send(500, "Something went wrong...");
}
else {
console.log("CSV file is saved");
//Send the file name and location back to the client
res.send('/temp/csvFile' + uniqueIdentifier + '.csv');
}
});
}
// After the CSV data is processed, save the file and send it to the client.
async.series([
processCSV
], finalize);
});
//Send the requested file back to the client
app.get('./app/:csvFile', function (req, res){
var c = req.params.csvFile;
res.download(c);
//Code to delete the file if it is temporary via fs.unlink
});
While it is not shown in the above code for simplicty, it is recommended that the /app routes sending and receiving this type of data are secured in some manner. Using Passport OIDCStrategy for the protected routes will look something like:
app.all('/app/*', function(req, res, next) {
//Check that the user has previously been authenticated
if (req.user){
next();
} else {
// require the user to log in
res.redirect("/login");
}
});

Answer 2

I dont think you can... Nodejs is serverside... so anything you put under Nodejs, will go to the server...
If the USER click on some button or some other event triggers a process that generates the CSV file, then the USER will have to choose where they want to save it or the file will be downloaded automatically to the default Downloads directory that was specified under USER's browser settings...