1. Before you can see your books, you’ll need make some changes. Open the bookstore directory in your text editor.

2. Now open config/routes.rb and add the following line inside the only block in the file:

   resources :books
   

3. Save your changes.

1. Go back to Terminal and make sure you’re in the bookstore directory.

2. Run rake routes.

   You should see a bunch of stuff about books along the lines of…

      Prefix Verb   URI Pattern               Controller#Action
       books GET    /books(.:format)          books#index
             POST   /books(.:format)          books#create
    new_book GET    /books/new(.:format)      books#new
   edit_book GET    /books/:id/edit(.:format) books#edit
        book GET    /books/:id(.:format)      books#show
             PATCH  /books/:id(.:format)      books#update
             PUT    /books/:id(.:format)      books#update
             DELETE /books/:id(.:format)      books#destroy
   

   rake routes prints a table of the available routes in your application. Since you added books as a resource in config/routes.rb, your application now has a bunch of book routes.

   The URI Pattern column in the table tells you how to reach the routes from a browser.

   For example, when your application is running locally you can reach /books by going to http://localhost:3000/books.

Let’s trying going to the /books route.

1. In Terminal, run rails server to start your application’s web server.

2. Now, open your favorite web browser and go to http://localhost:3000/books.

   If I had to guess, you probably got an error 🙃

We’ve run into a problem, but Rails is giving us some info to help us understand what’s going on.

You’re getting a Routing Error because there’s an uninitialized constant called BooksController. Rails is expecting your application to have a BooksController, but it doesn’t have one. Let’s create it!

1. Go back to Terminal and stop your rails server by running Ctrl-c.

2. Create the BooksController by running touch app/controllers/books_controller.rb.

3. Restart your web server by running rails server, and try going to http://localhost:3000/books again.

   That still errored, didn’t it? But hey, at least you got a new error!

1. If your text editor isn’t already open, open it and go to the bookstore directory.

2. Now, open app/controllers/books_controller.rb.

3. See, it’s empty 😝

   touch creates empty files. You used it to create an empty file called app/controllers/books_controller.rb.

The error you got said something about there being a missing constant BooksController. Let’s add it.

1. Add the following code to app/controllers/books_controller.rb:

   class BooksController < ApplicationController
   end
   

   That should define the constant Rails was looking for.

2. Save the file and try going to http://localhost:3000/books again.

   New error!

This new error is telling us that your BooksController doesn’t have an index action. That kinda makes sense - we didn’t add very much code to the BooksController. But why does it care that the index action is missing?

Remember the routing table? Kinda? Don’t worry, it’s fuzzy for me too. Let’s pull it up again.

1. Go back to Terminal and stop the rails server by running Ctrl-c.

2. Now, run rake routes. Voila - the routing table.

   The first entry in the routing table is for the /books path.

   Prefix Verb   URI Pattern       Controller#Action
    books GET    /books(.:format)  books#index
   

   The last column tells us which controller and action get run when we go to the /books path.

   The URI Pattern /books(.:format) maps to the Controller#Action pair of books#index. This tells us requests to the /books path will be routed to the BooksController index action.

   Clear as mud, right? Don’t worry, it’ll make more sense later.

3. Now that we (kinda) know why we’re trying to run the index action, let’s add it.

   Before we go on, restart your web server by running rails server.

1. In your text editor, open the BooksController and add the following method inside the BooksController class.

   def index
   end
   

2. Save your changes and try going to http://localhost:3000/books again.

   

1. Stop your rails server by running Ctrl-c.

2. All templates live in the app/views directory.

   app/views will have directories for each of the controllers in your application. By default, a controller’s template directory will be the name of the controller…minus the controller.

   For example, the templates for the BooksController will live in the app/views/books directory.

   Create the BooksController template directory by running mkdir app/views/books.

3. Now, create the template for the BooksController’s index action by running touch app/views/books/index.html.erb.

4. Restart your web server.

   (Remember? Start your web server by running rails server.)

5. Now, try going to http://localhost:3000/books.

   The page might be blank, but that means no errors!

Ok, let’s make this page a little more interesting.

1. In your text editor, open the template we made (app/views/books/index.html.erb) and add the following line:

   <h1>Welcome to My Super Rad Bookstore!</h1>
   

2. Save your changes and go to http://localhost:3000/books again.

   Yay! 🎉

Before you can show all of your books in the browser, you have to make the books data available through your application’s BooksController index action.

1. In your text editor, open app/controllers/books_controller.rb. Inside the index method, add the following line:

   @books = Book.all
   

   That line might look a little familiar. In Chapter 2, we used Book.all to list all your books on the rails console.

   We’re using the same method again so we can render your books in the browser.

2. Save your changes.

By making that change to the BooksController index action, you’ve made book data available to your index template.

Let’s see what you can do with it.

1. In your text editor, open app/views/books/index.html.erb and add the following line to the end of the file:

   <%= @books[0].title %>
   

2. Save your changes and try going to http://localhost:3000/books again.

1. In your text editor, open app/views/books/index.html.erb.

2. Remember that line you added to the end of the file?

   <%= @books[0].title %>
   

   Change it so it looks like this:

   <%= @books[1].title %>
   

3. Can you guess what this will change? Reload http://localhost:3000/books to see what happens.

1. Spend some time and see if you can get all the book titles to render. If you’ve been following along with the tutorial, you should have seven books in your application.

   If you know some HTML, try listing the titles in an unordered list.

   Don’t know very much HTML? Don’t worry about it - you’ll get familiar with it reaaaal soon. Just focus on getting the titles to render.

1. What did you come up with?

   One way may have been to list out each book like this:

   <%= @books[0].title %>
   <%= @books[1].title %>
   <%= @books[2].title %>
   <%= @books[3].title %>
   <%= @books[4].title %>
   <%= @books[5].title %>
   <%= @books[6].title %>
   

   That renders all the book titles, but they end up getting rendered on a single line.

2. If you know some HTML, you may have thrown in a few brs to give the titles some space like this:

   <%= @books[0].title %>
   <br>
   <%= @books[1].title %>
   <br>
   <%= @books[2].title %>
   <br>
   <%= @books[3].title %>
   <br>
   <%= @books[4].title %>
   <br>
   <%= @books[5].title %>
   <br>
   <%= @books[6].title %>
   

3. Better yet, you may have even used an unordered list:

   <ul>
     <li><%= @books[0].title %></li>
     <li><%= @books[1].title %></li>
     <li><%= @books[2].title %></li>
     <li><%= @books[3].title %></li>
     <li><%= @books[4].title %></li>
     <li><%= @books[5].title %></li>
     <li><%= @books[6].title %></li>
   </ul>
   

4. If you used an unordered list, great!

   If not, no worries - update your solution to use an unordered list.

1. Go back to your terminal and quit the rails server by running Ctrl-c.

2. Now, start the rails console by running…rails console.

3. Run the following code:

   books = Book.all
   

   You now have a books variable that’s been assigned all the books in your application’s database. books can be thought of as a Ruby Array.

   Sound familiar 😉

4. Now, try running the following:

   books.each { |book| puts book.title }
   

   What happened?

   You used the each method to iterate over each book and print its title.

5. The curly braces ({}) after each are the start and end of a block. We’ve seen the other block notation before - it starts with a do and ends with an end.

   Try running the following:

   books.each do |book|
     puts book.title
   end
   

   The syntax might be different, but it’s the same result - each of the book titles are printed.

6. At the beginning of the block, you have a couple of pipes surronding book

   books.each { |book| ... }
   

   This is called a block parameter. In this case, it lets you access each book so you can print its title.

   Before, we would’ve manually gone through each book to print its title.

   puts books[0].title
   puts books[1].title
   ...
   

   Now, each lets us do it in a lot less code.

   books.each { |book| puts book.title }
   

7. Try playing with the each method to see what else you can print out. You should be able print things like the book ids, authors, and quantities.

8. When you’re done exploring, run exit to exit the rails console. Then, restart the rails server.

Let’s put this new knowledge to work.

1. In your text editor, open app/views/books/index.html.erb.

2. At the end of the file, add a new, empty unordered list. It should look like this:

   <ul>
   </ul>
   

   Inside the new unordered list, we’ll want to iterate over all the books assigned to @books and render a list item for each book title.

   We can iterate over @books by using the each method.

   You’ve used the each method on the rails console, but how will you use it in your template?

3. To run Ruby code in your template, you have to put it inside some funny looking brackets:

   <% ... %>
   

   Everything inside <% %> will get run in your template.

   We’ve seen something similar before. Remember how you got the book titles to render?

   <%= @books[0].title %>
   

   The syntax is slightly different. <%= %> runs Ruby code and renders the result in your template.

   <% %> on the other hand only runs Ruby code. It does not render the result of that code.

   With that in mind, add the following code inside your new unordered list:

   <% @books.each do |book| %>
   <% end %>
   

4. Save your changes and revisit http://localhost:3000/books. Did anything change?

   Nothing changed! You’re running @books.each in your template, but since it’s inside <% %> the result of that block isn’t rendered.

Now that you have your block set up, you’re ready to render some book titles.

1. Spend a few minutes and try to get each book title to render as a list item inside the block.

   Remember, inside the block each book is availble to you as book.

   When you’re done, you should see two identical unordered lists on http://localhost:3000/books.

1. Did you get it?! Your new unordered list should look something like this:

   <ul>
     <% @books.each do |book| %>
       <li><%= book.title %></li>
     <% end %>
   </ul>
   

   Update your solution to match this solution.

2. Compare your two unordered lists. They both end in the same result, but one required a little more effort.

   <ul>
     <li><%= @books[0].title %></li>
     <li><%= @books[1].title %></li>
     <li><%= @books[2].title %></li>
     <li><%= @books[3].title %></li>
     <li><%= @books[4].title %></li>
     <li><%= @books[5].title %></li>
     <li><%= @books[6].title %></li>
   </ul>
   
   <ul>
     <% @books.each do |book| %>
       <li><%= book.title %></li>
     <% end %>
   </ul>
   

   We can take advantage of the ability to run Ruby code inside Rails templates to do things quickly.

3. You don’t need to show both unordered lists, so go ahead and remove the first one.

Now that you have book titles rendering, let’s try adding some information.

1. Update the books unordered lists so it includes the book author next to each author like this:

   why’s (poignant) Guide to Ruby by why the lucky stiff

1. What did you come up with? Compare your solution with people around you.

   Inside the @books.each block, you should’ve edited the list item so it renders each book’s author next to its title.

   <li><%= book.title %> by <%= book.author %></li>
   

2. Update your solution to match this solution.

3. When you’re done, stop your application’s web server by running Ctrl-C.