A Simple Server in Node.js

In this video we are going to ignore PostgreSQL for a moment and just learn how to get a simple nodejs server working.

After that, we will add in postgres.

HTTP Requests

Initially, we will be focusing on two types of requests:

Get Requests

This request is used when the request is idempotent meaning that the request results in no changes to the server or database. An example of this would be a search request–we just query the database for the search results and nothing changes in the database or server.

Put Requests

This request is used when changes are made to the database. For example, when the request results in adding something to the database.

CRUD

The acronym CRUD refers to all of the major functions that are implemented in persistant storage including relational database applications.

• CREATE
• READ
• UPDATE
• DELETE

Each letter in the acronym can map to a standard Structured Query Language (SQL) statement, and the related http requests

The code

Step 1

Create a new directory

mkdir campgrounds
cd campgrounds

and

npm init

then

npm install --save pg express 

This step installs express

express is a minimal node web application framework. It is designed to build web applications that use the requests we just discussed. POST, GET, DELETE. we will see it in action in a few moments.

Step 2 Create index.js – Hello world

using your favorite editor

const express = require("express");

const app = express();

app.set("port", 8080);

app.get("/hello", (req, res) => {
	res.json("Hello World!");
});

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

To run the code type

node index.js

Point your browser to http://localhost:8080

Step 3 - a get request

Just a quick demo printing out the query parameters:

app.get("/vacancy", (req, res) => {
	console.log(req.query);
});

then the real code

app.get("/vacancy", (req, res) => {
	console.log(req.query.q);
	const campground = req.query.q;
	if (campground == "Saddle") {
		res.json({ campground: campground, sites: 5 });
	} else {
		res.json({ campground: campground, sites: 0 });
	}
});

Try it out with http://localhost:8080/vacancy?q=Saddle

Step 4 - Post request

const bodyParser = require("body-parser");
app.use(bodyParser.json({ type: "application/json" }));
app.use(bodyParser.urlencoded({ extended: true }));

app.post("/reserve", (req, res) => {
	console.log(req.body);
	const first = req.body.firstname;
	const last = req.body.lastname;
	const campground = req.body.campground;
	const sites = req.body.sites;
	res.json({ reservation_number: 1, campground: campground });
});