Establishes a connection to a PostgreSQL database using credentials and handles create and read operations on the database

app.js

// Node-postgres, supports for callbacks, promises, async/await,
const pg = require("pg");

// Parse connectionString to get username, password, database name, server, port,...
const parse = require('pg-connection-string').parse;

// Our config details
let config = parse(connectionString);

// Set up a new client using our config details
let client = new pg.Client(config);

client.connect(function (err) {
    if (err) {
        console.log(err);
        process.exit(1);
    } else {
        client.query(
            "CREATE TABLE IF NOT EXISTS objects (object varchar(256) NOT NULL, definition varchar(256) NOT NULL)",
            function (err, result) {
                if (err) {
                    console.log(err);
                }
            }
        );
    }
});

function addObject(object, definition) {
    return new Promise(function (resolve, reject) {
        let queryText = "INSERT INTO objects(object,definition) VALUES($1, $2)";
        client.query(
            queryText, [object, definition],
            function (error, result) {
                if (error) {
                    reject(error);
                } else {
                    resolve(result);
                }
            }
        );
    });
}

function getObject() {
    return new Promise(function (resolve, reject) {
        client.query("SELECT * FROM objects ORDER BY object ASC", function (
            err,
            result
        ) {
            if (err) {
                reject(err);
            } else {
                resolve(result.rows);
            }
        });
    });
}

// Send the data to the addObject function and send a response if successful
app.put("/objects", function (request, response) {
    addObject(request.body.object, request.body.definition)
        .then(function (resp) {
            response.send(resp);
        })
        .catch(function (err) {
            response.status(500).send(err);
        });
});

// Use the getObject function to get a list of objects and definitions from the database
app.get("/objects", function (request, response) {
    getObject()
        .then(function (objects) {
            response.send(objects);
        })
        .catch(function (err) {
            response.status(500).send(err);
        });
});

// Listen for a connection
app.listen(port, function () {
    console.log("Server is listening on port " + port);
});