Folder structure

                       /controllers
                            authorController.js
                            bookController.js
                            bookinstanceController.js
                            genreController.js

                        

Author controller

                        const Author = require("../models/author");

// Display list of all Authors.
exports.author_list = (req, res) => {
  res.send("NOT IMPLEMENTED: Author list");
};

// Display detail page for a specific Author.
exports.author_detail = (req, res) => {
  res.send(`NOT IMPLEMENTED: Author detail: ${req.params.id}`);
};

// Display Author create form on GET.
exports.author_create_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Author create GET");
};

// Handle Author create on POST.
exports.author_create_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Author create POST");
};

// Display Author delete form on GET.
exports.author_delete_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Author delete GET");
};

// Handle Author delete on POST.
exports.author_delete_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Author delete POST");
};

// Display Author update form on GET.
exports.author_update_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Author update GET");
};

// Handle Author update on POST.
exports.author_update_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Author update POST");
};

BookInstance controller

const BookInstance = require("../models/bookinstance");

// Display list of all BookInstances.
exports.bookinstance_list = (req, res) => {
  res.send("NOT IMPLEMENTED: BookInstance list");
};

// Display detail page for a specific BookInstance.
exports.bookinstance_detail = (req, res) => {
  res.send(`NOT IMPLEMENTED: BookInstance detail: ${req.params.id}`);
};

// Display BookInstance create form on GET.
exports.bookinstance_create_get = (req, res) => {
  res.send("NOT IMPLEMENTED: BookInstance create GET");
};

// Handle BookInstance create on POST.
exports.bookinstance_create_post = (req, res) => {
  res.send("NOT IMPLEMENTED: BookInstance create POST");
};

// Display BookInstance delete form on GET.
exports.bookinstance_delete_get = (req, res) => {
  res.send("NOT IMPLEMENTED: BookInstance delete GET");
};

// Handle BookInstance delete on POST.
exports.bookinstance_delete_post = (req, res) => {
  res.send("NOT IMPLEMENTED: BookInstance delete POST");
};

// Display BookInstance update form on GET.
exports.bookinstance_update_get = (req, res) => {
  res.send("NOT IMPLEMENTED: BookInstance update GET");
};

// Handle bookinstance update on POST.
exports.bookinstance_update_post = (req, res) => {
  res.send("NOT IMPLEMENTED: BookInstance update POST");
};

Genre controller

const Genre = require("../models/genre");

// Display list of all Genre.
exports.genre_list = (req, res) => {
  res.send("NOT IMPLEMENTED: Genre list");
};

// Display detail page for a specific Genre.
exports.genre_detail = (req, res) => {
  res.send(`NOT IMPLEMENTED: Genre detail: ${req.params.id}`);
};

// Display Genre create form on GET.
exports.genre_create_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Genre create GET");
};

// Handle Genre create on POST.
exports.genre_create_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Genre create POST");
};

// Display Genre delete form on GET.
exports.genre_delete_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Genre delete GET");
};

// Handle Genre delete on POST.
exports.genre_delete_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Genre delete POST");
};

// Display Genre update form on GET.
exports.genre_update_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Genre update GET");
};

// Handle Genre update on POST.
exports.genre_update_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Genre update POST");
};

Book controller

const Book = require("../models/book");

exports.index = (req, res) => {
  res.send("NOT IMPLEMENTED: Site Home Page");
};

// Display list of all books.
exports.book_list = (req, res) => {
  res.send("NOT IMPLEMENTED: Book list");
};

// Display detail page for a specific book.
exports.book_detail = (req, res) => {
  res.send(`NOT IMPLEMENTED: Book detail: ${req.params.id}`);
};

// Display book create form on GET.
exports.book_create_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Book create GET");
};

// Handle book create on POST.
exports.book_create_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Book create POST");
};

// Display book delete form on GET.
exports.book_delete_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Book delete GET");
};

// Handle book delete on POST.
exports.book_delete_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Book delete POST");
};

// Display book update form on GET.
exports.book_update_get = (req, res) => {
  res.send("NOT IMPLEMENTED: Book update GET");
};

// Handle book update on POST.
exports.book_update_post = (req, res) => {
  res.send("NOT IMPLEMENTED: Book update POST");
};

Create the catalog route module

/routes
    index.js
    users.js
    catalog.js

Open /routes/catalog.js and copy in the code below:

const express = require("express");
const router = express.Router();

// Require controller modules.
const book_controller = require("../controllers/bookController");
const author_controller = require("../controllers/authorController");
const genre_controller = require("../controllers/genreController");
const book_instance_controller = require("../controllers/bookinstanceController");

/// BOOK ROUTES ///

// GET catalog home page.
router.get("/", book_controller.index);

// GET request for creating a Book. NOTE This must come before routes that display Book (uses id).
router.get("/book/create", book_controller.book_create_get);

// POST request for creating Book.
router.post("/book/create", book_controller.book_create_post);

// GET request to delete Book.
router.get("/book/:id/delete", book_controller.book_delete_get);

// POST request to delete Book.
router.post("/book/:id/delete", book_controller.book_delete_post);

// GET request to update Book.
router.get("/book/:id/update", book_controller.book_update_get);

// POST request to update Book.
router.post("/book/:id/update", book_controller.book_update_post);

// GET request for one Book.
router.get("/book/:id", book_controller.book_detail);

// GET request for list of all Book items.
router.get("/books", book_controller.book_list);

/// AUTHOR ROUTES ///

// GET request for creating Author. NOTE This must come before route for id (i.e. display author).
router.get("/author/create", author_controller.author_create_get);

// POST request for creating Author.
router.post("/author/create", author_controller.author_create_post);

// GET request to delete Author.
router.get("/author/:id/delete", author_controller.author_delete_get);

// POST request to delete Author.
router.post("/author/:id/delete", author_controller.author_delete_post);

// GET request to update Author.
router.get("/author/:id/update", author_controller.author_update_get);

// POST request to update Author.
router.post("/author/:id/update", author_controller.author_update_post);

// GET request for one Author.
router.get("/author/:id", author_controller.author_detail);

// GET request for list of all Authors.
router.get("/authors", author_controller.author_list);

/// GENRE ROUTES ///

// GET request for creating a Genre. NOTE This must come before route that displays Genre (uses id).
router.get("/genre/create", genre_controller.genre_create_get);

//POST request for creating Genre.
router.post("/genre/create", genre_controller.genre_create_post);

// GET request to delete Genre.
router.get("/genre/:id/delete", genre_controller.genre_delete_get);

// POST request to delete Genre.
router.post("/genre/:id/delete", genre_controller.genre_delete_post);

// GET request to update Genre.
router.get("/genre/:id/update", genre_controller.genre_update_get);

// POST request to update Genre.
router.post("/genre/:id/update", genre_controller.genre_update_post);

// GET request for one Genre.
router.get("/genre/:id", genre_controller.genre_detail);

// GET request for list of all Genre.
router.get("/genres", genre_controller.genre_list);

/// BOOKINSTANCE ROUTES ///

// GET request for creating a BookInstance. NOTE This must come before route that displays BookInstance (uses id).
router.get(
  "/bookinstance/create",
  book_instance_controller.bookinstance_create_get
);

// POST request for creating BookInstance.
router.post(
  "/bookinstance/create",
  book_instance_controller.bookinstance_create_post
);

// GET request to delete BookInstance.
router.get(
  "/bookinstance/:id/delete",
  book_instance_controller.bookinstance_delete_get
);

// POST request to delete BookInstance.
router.post(
  "/bookinstance/:id/delete",
  book_instance_controller.bookinstance_delete_post
);

// GET request to update BookInstance.
router.get(
  "/bookinstance/:id/update",
  book_instance_controller.bookinstance_update_get
);

// POST request to update BookInstance.
router.post(
  "/bookinstance/:id/update",
  book_instance_controller.bookinstance_update_post
);

// GET request for one BookInstance.
router.get("/bookinstance/:id", book_instance_controller.bookinstance_detail);

// GET request for list of all BookInstance.
router.get("/bookinstances", book_instance_controller.bookinstance_list);

module.exports = router;

Update the index route module

Open /routes/index.js

router.get("/", function (req, res) {
  res.redirect("/catalog");
});

Update app.js

Open app.js

const indexRouter = require("./routes/index");
const usersRouter = require("./routes/users");
const catalogRouter = require("./routes/catalog"); //Import routes for "catalog" area of site

app.use("/", indexRouter);
app.use("/users", usersRouter);
app.use("/catalog", catalogRouter); // Add catalog routes to middleware chain.

testing

http://localhost:3000/
http://localhost:3000/catalog
http://localhost:3000/catalog/books
http://localhost:3000/catalog/bookinstances/
http://localhost:3000/catalog/authors/
http://localhost:3000/catalog/genres/
http://localhost:3000/catalog/book/5846437593935e2f8c2aa226
http://localhost:3000/catalog/book/create