How to download csv file using fast csv in node js - node.js

Question

I want to export my data into csv file so for that purpose i used fast-csv in node js. its working fine my code is
var csv = require("fast-csv");
app.get('/file/exportToExcel', function(req, res) {
var whereCondi = {
'Id': req.query.id,
}
var response = {};
table.find(whereCondi, function(err, tableData) {
if (err) {
response.status = 400;
response.message = err.message;
res.send(response);
} else {
var csvStream = csv.createWriteStream({headers: true}),
writableStream = fs.createWriteStream("code.csv");
writableStream.on("finish", function() {
});
csvStream.pipe(writableStream);
for (var i = 0; i < tableData.length; i++) {
csvStream.write({allcodes: tableData[i].code});
}
csvStream.end();
}
});
});
but the problem is its saving that csv file in my root folder i want to download that csv file when user click on export to excel please help me.

Answer 1

writableStream = fs.createWriteStream("coupons.csv");
This looks to be your problem if I'm understanding you correctly. The current code saves the csv file relative to the app file (basically in the same directory in your case).
Try something like:
writableStream = fs.createWriteStream("./some/directory/coupons.csv");

Answer 2

You should create the csv file in your directory an then delete it in the same way like that
const express = require('express')
const objectstocsv = require('objects-to-csv')
const fs = require("fs")
const app = express()
var data = [
{code: 'CA', name: 'California'},
{code: 'TX', name: 'Texas'},
{code: 'NY', name: 'New York'},
];
const PORT = process.env.PORT || 5000
app.get('/',async(req,res) => {
const csv = new objectstocsv(data);
// Save to file:
await csv.toDisk('./test.csv');
// Download the file
res.download("./test.csv",() => {
//Then delete the csv file in the callback
fs.unlinkSync("./test.csv")
})
})

Answer 3

Very late to the game but wanted to add in case other people were encountering same hurdle. Not sure if this is an ideal solution since I just started learning, but I got around this problem by wrapping the csv creation in an async function, and having that function called when a user clicks on a button.
Essentially, user clicks button > GET request to specific path > export csv and render success page.
index.js or server js file
const exportToCsv = () => {
...some code to get data and generate csv...
};
app.get('/download', async (req, res) => {
exportToCsv();
res.render('<your desired view>');
};
view or html
<button type='submit' onclick='someNavFunction()'>Export</button>
The someNavFunction() can be a helper function to navigate to a new path or some other solution that helps you hit '/download' that you created route for in server file.
This solution worked for me because I wanted to render a success page after download. You can add additional validation to only render if exported successfully etc.