server.js

const express = require('express');
const mysql = require('mysql');
const app = express();

app.use(function(req, res, next) {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
  next();
});
app.set('port', process.env.PORT || 3001);

// Express only serves static assets in production
console.log('NODE_ENV: ', process.env.NODE_ENV);
if (process.env.NODE_ENV === 'production') {
  app.use(express.static('client/build'));

  // Return the main index.html, so react-router render the route in the client
  app.get('/', (req, res) => {
    res.sendFile(path.resolve('client/build', 'index.html'));
  });
}

const host = 'localhost';
const user = 'root';
const pswd = 'password';
const dbname = 'books';

// config db ====================================
const pool = mysql.createPool({
  host: host,
  user: user,
  password: pswd,
  port: '3306',
  database: dbname
});

const COLUMNS = ['last_name', 'first_name'];

app.get('/api/books', (req, res) => {
  const firstName = req.query.firstName;

  if (!firstName) {
    res.json({
      error: 'Missing required parameters'
    });
    return;
  }

  let queryString = ``;
  if (firstName == '*') {
    queryString = `SELECT * from authors`;
  } else {
    queryString = `SELECT * from authors WHERE first_name REGEXP '^${firstName}'`;
  }

  pool.query(queryString, function(err, rows, fields) {
    if (err) throw err;

    if (rows.length > 0) {
      res.json(
        rows.map(entry => {
          const e = {};
          COLUMNS.forEach(c => {
            e[c] = entry[c];
          });
          return e;
        })
      );
    } else {
      res.json([]);
    }
  });
});

app.listen(app.get('port'), () => {
  console.log(`Find the server at: http://localhost:${app.get('port')}/`); // eslint-disable-line no-console
});