Book list page

The book list controller function needs to get a list of all Book objects in the database, sort them, and then pass these to the template for rendering.

Open /controllers/bookController.js. Find the exported book_list() controller method and replace it with the following code.

// Display list of all books.
exports.book_list = asyncHandler(async (req, res, next) => {
  const allBooks = await Book.find({}, "title author")
    .sort({ title: 1 })
    .populate("author")
    .exec();

  res.render("book_list", { title: "Book List", book_list: allBooks });
});

The route handler calls the find() function on the Book model, selecting to return only the title and author as we don't need the other fields (it will also return the _id and virtual fields), and sorting the results by the title alphabetically using the sort() method. We also call populate() on Book, specifying the author field—this will replace the stored book author id with the full author details. exec() is then daisy-chained on the end in order to execute the query and return a promise.

The route handler uses await to wait on the promise, pausing execution until it is settled. If the promise is fulfilled, the results of the query are saved to the allBooks variable and the handler continues execution.

The final part of the route handler calls render(), specifying the book_list (.pug) template and passing values for the title and book_list into the template.

Create /views/book_list.pug and copy in the text below.

extends layout

block content
  h1= title
  if book_list.length
    ul
      each book in book_list
        li
          a(href=book.url) #{book.title}
          |  (#{book.author.name})

  else
    p There are no books.

The view extends the layout.pug base template and overrides the block named 'content'. It displays the title we passed in from the controller (via the render() method) and iterates through the book_list variable using the each-in syntax. A list item is created for each book displaying the book title as a link to the book's detail page followed by the author name. If there are no books in the book_list then the else clause is executed, and displays the text 'There are no books'.

Of interest here is that each book is defined as two lines, using the pipe for the second line. This approach is needed because if the author name were on the previous line then it would be part of the hyperlink.

Run the application (see Testing the routes for the relevant commands) and open your browser to http://localhost:3000/. Then select the All books link. If everything is set up correctly, your site should look something like the following screenshot.

• Return to Express Tutorial Part 5: Displaying library data.
• Proceed to the next subarticle of part 5: BookInstance list page.