Book list page
Next we'll implement our book list page. This page needs to display a list of all books in the database along with their author, with each book title being a hyperlink to its associated book detail page.
Controller
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.
js
// 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.
View
Create /views/book_list.pug and copy in the text below.
pug
extends layout
block content
h1= title
ul
each book in book_list
li
a(href=book.url) #{book.title}
| (#{book.author.name})
else
li 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
-else
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'.
Note: We use book.url
to provide the link to the detail record for each book (we've implemented this route, but not the page yet). This is a virtual property of the Book
model which uses the model instance's _id
field to produce a unique URL path.
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.
What does it look like?
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.
Next steps
- Return to Express Tutorial Part 5: Displaying library data.
- Proceed to the next subarticle of part 5: BookInstance list page.