server.js

const express = require("express")
const server = express()

server.use(express.static('public'))

server.use(express.urlencoded({extended: true}))

const Pool = require('pg').Pool
const db = new Pool({
    user: 'postgres',
    password: 'm',
    host: 'localhost',
    port: 5432,
    database: 'doe'
})

const nunjucks = require("nunjucks")
nunjucks.configure("./", {
    express: server,
    noCache: true,
})

server.get("/", function(req, res){
    db.query("SELECT * FROM donors", function(err, result){
        if (err) return res.send("Erro no banco de dados.")   

        const donors = result.rows;
        return res.render("index.html", {donors})
    })
})

server.post("/", function(req, res){
    const name = req.body.name
    const email = req.body.email
    const blood = req.body.blood

    if (name == "" || email == "" || blood == ""){
        return res.send("Todos os campos são obrigatórios.")
    }

    const query = `
        INSERT INTO "donors" ("name", "email", "blood")
        VALUES ($1, $2, $3)
    `
    const values = [name, email, blood]

    db.query(query, values, function(err){
        if (err) return res.send("Erro no banco de dados.")    

        return res.redirect("/")
    })

})

server.listen(3000)