Node/expresss endpoint to generate a downloadable link to csv file of mongodb collection "logs"

log.controller.js

const fs = require('fs');

const json2csv = require('json2csv');  //"json2csv": "^3.7.3"
const moment = require('moment');  	   //"moment": "^2.17.1"
const mkdirp = require('mkdirp');      //"mkdirp": "^0.5.1",
const del = require('del');			       //"del": "^2.2.2" 

const fields = ['collection', 'message', 'createdAt'];
const Log = require ( './log.model');
const Controller = {};

Controller.export = function(req, res){
    Log.find({})
        .sort('-createdAt')
        .exec(function(err, logs){
            if(err){
                return res.status(500).end();
            }
            else{
                mkdirp('./public/exports', function (err) { //create "exports" dir in a static folder (public in this case, defined during express configuration)
                    if (err){
                        return res.json(err).status(500);
                    }
                    else{
                        var csv = json2csv({ data: logs, fields: fields });
                        var dateTime = moment().format('YYYYMMDDhhmmss');
                        var filePath = 'exports/logs'+dateTime+'.csv';
                        fs.writeFile('./public/' + filePath, csv, function(err) {
                            if (err){
                                return res.json(err).status(500);
                            }
                            else{
                                setTimeout(function(){ // delete exports directory after 30 seconds
                                    del.sync(['./public/exports']);
                                }, 30000)
                                return res.json(filePath);
                            }
                        });
                    }
                });
            }
        })
};

module.exports = Controller;

log.model.js

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

var logSchema = new Schema({
    collection:{
        type: String
    },
    message: {
        type: String
    },
    createdAt: {
        type: Date,
        required: true,
        default: Date.now
    }
});

module.exports = mongoose.model('Log', logSchema);