micro-rest-api-server

micro-rest-api-server.js

// imports
const Express = require("express");
const bodyParser = require("body-parser");

// Some datastore to play with.
const bookDb = initDb();

// Set up express app.
const app = new Express();

// Express Routes.
app.get("/book", getBooks); // send all books. 
app.route("/book/:id(\\d+)") // book with a numeric id
    .get(getBook) // get a single book by id.
    .post(bodyParser.json(), setBook) // store a single book by id. Parse body before hand.
    .delete(deleteBook); // delete a single book by id.

// Starting Server. Console when server is ready.
app.listen(8080, () => console.log("Server Started"));
    
/**
 * Behind the scenes functions.
 */
function getBooks(req, res) {
    // Turn map into array, Inject BookId into objects.
    let modifiedBooks = Array.from(bookDb.entries())
        .map(([key, book]) => Object.assign({"_id": key}, book));
    
    // Send modified array.
    res.json(modifiedBooks);
}
function getBook(req, res) {
    let bookId = parseInt(req.params.id); // Make sure db has the book needed.
    if ( !bookDb.has(bookId) ) {
        return res.status(404).end(); // if no book, send NOT FOUND.
    }
    res.json(bookDb.get(bookId)); // send book object.
}
function setBook(req, res) {
    let bookId = parseInt(req.params.id);
    let book = req.body;
    
    // Make sure data coming in from outside is good.
    // This is very crucial for security reasons.
    // Not implemented for this demo.
    let invalidReason = isInvalidBook(bookId, book);
    
    if ( invalidReason ) {
        return res.status(400).end(invalidReason); // if book is not valid, send BAD REQUEST, and reasons why.
    }
    
    // Store book in db.
    bookDb.set(bookId, book);
    
    res.send(); // Send acknowledgement.
}
function deleteBook(req, res) {
    let bookId = parseInt(req.params.id);
    // Make sure book exists in db.
    if ( !bookDb.has(bookId) ) {
        return res.status(404).end(); // If does not exist, send NOT FOUND.
    }
    // Delete book from db.
    bookDb.delete(bookId);
}
function isBookInvalid(bookId, book) {
    // test book object to see if it is invalid
    // return reason why if it is invalid.
    // if valid, return falsey.
    return false;
}
function initDb() {
    // Some seed data for demo.
    return new Map([
        [1, { "title": "Twisted Metal", "author": "Tony Ballantyne" }], 
        [2, { "title": "Blood and Iron", "author": "Tony Ballantyne" }]
    ]);
}