simple tools to shorten url

urlshortener.js

const express = require('express')
const app = express()
const sqlite = require('sqlite3')
const bodyPraser = require('body-parser')
app.use(bodyPraser.urlencoded({extended: false}))
app.use(bodyPraser.json())

const PORT = 8114


let db = new sqlite.Database('./shorturl.db' , sqlite.OPEN_READWRITE | sqlite.OPEN_CREATE , (err)=> {
    if (err) {
        console.err('error to connect sqlite')
    }
    console.log('connect to sqlite success')
})

db.run("create table if not exists short_url(short_url varchar(50),url varchar(50))")

let insertOrUpdate = function(short_url, url, res) {
    db.get(`select * from short_url where short_url='${short_url}'`, (err, row)=>{
        if (row) {
            db.run(`update short_url set url='${url}' where short_url='${short_url}'`, (err) =>{
                if (err) {
                    res.status(500).json({error: err.message})
                }
            })
        } else {
            db.run(`insert into short_url(short_url,url) values ('${short_url}','${url}')`, (err) =>{
                if (err) {
                    res.status(500).json({error: err.message})
                }
            })
        }

})}


app.post('/set/', function(req, res, next) {
    let url = req.body.url
    // let shortedURL = req.body.shortedURL || Math.random().toString(36).substring(2,8)
    let shortedURL = req.body.shortedURL
    console.log(url)
    console.log(shortedURL)
    insertOrUpdate(shortedURL, url)
    res.status(200).json({error: 'success'})
})

app.get('/:shortedURL', function(req, res,next) {
    let shortedURL = req.params.shortedURL
    db.get(`select url from short_url where short_url='${shortedURL}' limit 1`, (err,row) =>{
        if (err) {
            console.error('fail to find record' + err.message)
        }
        console.log(`url = ${row.url}` )
        res.redirect(row.url)
    })
})

app.listen(PORT, () =>{
    console.log("url shorten service start on port " + PORT)
})