restql.js

const Sql = require('mysql');
const Express = require('express');

const app = Express();
const port = process.argv[6] || '8080';
const database = process.argv[5];
const pool = Sql.createPool({
    database: database,
    connectionLimit: 10,
    host: process.argv[2],
    user: process.argv[3],
    password: process.argv[4]
});

async function startServer() {
    app.use(Express.json());
    await GenerateRoutes();
    app.listen(parseInt(port));
}   

async function Query(...args) {
    return new Promise((resolve, reject) => {
        args.push((error, results, fields) => {
            if (error) return resolve(error);
            resolve([results, fields])
        });
        pool.query(...args);
    });
}

function WHERE(json) {
    return Object.keys(json)
        .map(key => `\`${key}\` = ?`)
        .join(' ');
}

async function GenerateRoutes() {
    return new Promise(async (resolve, reject) => {
        const tables = (await Query('show tables'))[0];
        let routesGenerated = tables.length;

        tables.forEach(async tableResult => {
            const id = {};
            const table = tableResult['Tables_in_' + database];
            const columns = (await Query(`describe ${table}`))[0]
                .filter(result => !result.Extra.length)
                .map(result => result.Field);
            const placeholders = '(' + columns.map(_ => '?').join(',') + ')';
            const columnTuple = '(' + columns.map(column => `\`${column}\``).join(',') + ')';
            id[(await Query(`show keys from ${table} where Key_name = 'PRIMARY'`))[0][0].Column_name] = 0;

            app.get(`/${table}`, async (req, resp) =>
                resp.send((await Query(`SELECT * FROM ${table}`)[0])));
            app.get(`/${table}/:id`, async (req, resp) =>
                resp.send((await Query(`SELECT * FROM ${table} ${WHERE(id)}`, req.params.id)[0])));
            app.delete(`/${table}/:id`, async (req, resp) =>
                resp.send((await Query(`DELETE FROM ${table} ${WHERE(id)}`, req.params.id)[0])));
            app.put(`/${table}/:id`, async (req, resp) => {
                const keys = Object.keys(req.body).filter(key => columns.includes(key));
                const cols = keys.map(key => `\`${key}\` = ?`).join(',');
                const values = keys.map(key => req.body[key]);
                values.push(req.params.id);
                resp.send((await Query(`UPDATE ${table} SET ${key} ${WHERE(id)}`, values))[0]);
            });
            app.post(`/${table}`, async (req, resp) => {
                const keys = Object.keys(req.body)
                    .filter(key => columns.includes(key))
                const values = keys.map(key => req.body[key]);
                await Query(`INSERT INTO ${table} (${keys.join(',')}) VALUES (${keys.map(_ => '?').join(',')})`, values);
                resp.end();
            });

            if (--routesGenerated === 0)
                resolve();
        });
    });
}

startServer();