How to export csv nodejs

Question

Hey I am trying to export a csv from node.js (pulling the data from mongodb). I already have the data being pulled and separated by commas and all, but now I am trying to figure out how to actually send it... I am sticking this code in my routes file. Any advice on how to take the array of data and send it to a user straight for download on request.

here is the code: (I attempted the the bottom part of the code the second function)

exports.downloadContacts = function(req, res) {
    async.waterfall([
        function(callback) {
            var source = [];
            Friend.find({userId: req.signedCookies.userid}, function(err, friends) {
                if(err) {console.log('err with friends for download');
                } else {
                    var userMap = {};
                    var friendIds = friends.map(function (user) {
                        userMap[user.friend_id] = user;
                        return user.friend_id;
                    });
                    console.log(friends);
                    User.find({_id: {$in: friendIds}}, function(err, users) {
                        if(err) {console.log(err); 
                        } else {
                            for(var i = 0; i < users.length; i++) {
                                console.log('users')
                                //console.log(users[i]);
                                source.push(users[i].firstNameTrue, users[i].lastNameTrue, users[i].emailTrue, users[i].phone, users[i].emailList, users[i].phoneList)
                            }
                            console.log(source);
                            callback(null, source);
                        }


                    });
                }


            });

        }
    ],
    function(err, source) {
        var result = [];

        res.contentType('csv');

        csv()
        .from(source)
        .on('data', function(data){ 
            result.push(data.join());
        })
        .on('end', function(){
            res.send(result.join('\n'));
        });
    });     
};

Answer 1

Here is what I did:

1. Use json2csv to build csv data from mongodb data

var json2csv = require('json2csv'); var fields = ['name', 'phone', 'mobile', 'email', 'address', 'notes']; var fieldNames = ['Name', 'Phone', 'Mobile', 'Email', 'Address', 'Notes']; var data = json2csv({ data: docs, fields: fields, fieldNames: fieldNames }); 

2. Send csv data to client

res.attachment('filename.csv'); res.status(200).send(data); 

Answer 2

Have you tried something like this with a content type as "application/octet-stream"

res.set('Content-Type', 'application/octet-stream');
res.send(<your data>);

or simply

res.send(Buffer.from(<your data>));

Express send() docs.

Answer 3

The json2csv package has been updated since the highest voted answer was written, the newer version has slightly different syntax:

        var { Parser } = require('json2csv')

        const fields = [{
            label: 'header 1',
            value: 'field1_name'
        }, {
            label: 'header 2',
            value: 'field2_name'
        }]

        const json2csv = new Parser({ fields: fields })

        try {
            const csv = json2csv.parse(data)
            res.attachment('data.csv')
            res.status(200).send(csv)
        } catch (error) {
            console.log('error:', error.message)
            res.status(500).send(error.message)
        }

res.attachment is a function and not an attribute. Needed to remove the equal sign for this to work.