Question

!! Express.js quesiton !!

I just started studying about Node.js with Express.js framework. I tried so hard but I have no idea how to solve these questions... I hope you guys can help me to solve those questions. Thank you :)

This is my problem :

1. DELETE /book?title=:book_title

   • always returns 204 Not Content status code even if the book is not present in the datastore.
   • no response body.

2. GET /books

   • returns 200 Success status code.
   • returns list of all books.
   • return format must be JSON: { "books": [{ "author":"joe", "title":"MyBook", "pages":234, "quality":"new"}, ... ] }

3. PUT /book

   • updates a single book on the list based on the title.
   • returns 200 Success status code when it finds the book and updates it successfully.
   • returns a single book formatted in JSON as the response body: ex. { "book": { "author":"joe", "title":"MyBook", "pages":234, "quality":"new" }} as long the body has the book and all its fields, the format does not matter.
   • for the PUT, please have your application accept a request body of content-type JSON and treat the title as the identifier when looking for the book for example, your cURL might look like: curl localhost:3000/book -X PUT -d '{"title":"...", "author":"...", ... }' -H 'content-type: application/json'
   • the request body can contain any of the attributes of a book, so if a matching attribute has a new value in the request body, update it, otherwise, ignore it for example, if the request body is {"title":"currentTitle", "author":"newtitle","nonexistentattribute":"nonexistentvalue"}, the datastore would update the book titled "currentTitle" with the new "author" value, but ignore the "nonexistentattribute" since that doesn't exist as an attribute for a book.
   • if the title is not found in the in-memory datastore, return a 404 status response code and whatever body you want to the user.

This is what I did so far(please fix the code..) :

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

app.get("/", (req, res) => {
res.send("Hi, This is Yi Wan's workpage")
});

var books = {
"books": [{
"author": "joe",
"title": "MyBook",
"pages": 234,
"quality": "new"
},
{
"author": "kevin",
"title": "YourBook",
"pages": 432,
"quality": "old"
}
]
}

app.delete('/book?title=:book_title', (req, res) => {
res.send(req.params.book_title);
res.status(204);
});

app.get('/books', (req, res) => {
res.status(200).send(JSON.stringify(books));
});

app.put('/book', (req, res) => {
// have no idea..
});

app.listen(3000, () => console.log("listening on port 3000"));

Answer 1

I have solved your DELETE and PUT methods and you can find the code with useful comments and the screenshots below.

CODE:

const express = require("express");
const app = express();

// Used to get json response body
app.use(express.json());

var books = [
{
author: "joe",
title: "MyBook",
pages: 234,
quality: "new"
},
{
author: "kevin",
title: "YourBook",
pages: 432,
quality: "old"
}
];

app.get("/", (req, res) => {
res.send("Hi, This is Yi Wan's workpage");
});

app.delete("/book/:book_title", (req, res) => {
const title = req.params.book_title;
// Filter books by book title
books = books.filter(book => book.title !== title);
res.sendStatus(204);
});

app.get("/books", (req, res) => {
res.status(200).send(JSON.stringify(books));
});

app.put("/book", (req, res) => {
const data = req.body;
// Missing data by user
if (!data) {
return res.status(404).send("Missing book information.");
}
// Finding book in the datastore
let book = books.filter(book => book.title === data.title);
if (!book.length) {
return res.status(404).send("Book not found.");
}
// map through books data store
books = books.map(book => {
// Check if book found
if (book.title === data.title) {
// Check if author field is present
if (data.author) {
// if new data is available then replace it with the old book data
book.author = book.author === data.author ? book.author : data.author;
}
// Check if author field is pages
if (data.pages) {
book.pages = book.pages === data.pages ? book.pages : data.pages;
}
// Check if author field is quality
if (data.quality) {
book.quality =
book.quality === data.quality ? book.quality : data.quality;
}
}
return book;
});
return res.status(200).send("Book updated successfully.");
});

app.listen(3000, () => console.log("listening on port 3000"));

IMAGES

OUTPUT: