1. Open Terminal and go to the bookstore directory.

2. Now, run rake routes.

   We’ve worked through a couple of the books routes. First, we used the index action to list all your application’s books. Then, we used the show action to show details for a given book.

   Now, we’ll use the new action to create a new book.

3. The path for the new action is /books/new.

   new_book GET    /books/new(.:format)      books#new
   

   Let’s try going to that path.

1. In Terminal, start your application’s web server by running rails server.

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

3. You got an error, but doesn’t it look familiar?

   Why you think you got an Unknown action error?

1. In your text editor, open the BooksController (app/controllers/boooks_controller.rb).

2. At the end of the BooksController add the new method.

   def new
   end
   

3. Save your changes, and revisit http://localhost:3000/books/new.

1. Go back to terminal and stop your application’s web server by running Ctrl-C.

2. Now, run touch app/views/books/new.html.erb to create the new action’s template.

3. Restart your application’s web server and revisit http://localhost:3000/books/new. What do you see?

   A blank page! 🎉

1. In your text editor, open app/views/books/new.html.erb and add the following code:

   <%= form_for(@book) do |f| %>
   <% end %>
   

   form_for is a method provided by Rails. It provides a consistent interface to build forms inside Rails applications.

   Here, we’re passing @book to form_for because we want to create a form for a book.

   form_for takes a block as its last argument. We haven’t done anything interesting inside the block, but that’ll change soon 😉

2. Save your changes and revisit http://localhost:3000/books/new.

1. Open the BooksController in your text editor and take a look at the new method.

   Is @book defined inside in the new method?

   def new
   end
   

   It’s nowhere to be found! That explains that error 😅

Let’s fix that error.

1. Inside the BooksController new method, add the following line:

   @book = Book.new
   

   @book is set to be a new book because we want to create a form for new books.

2. Save your changes and revisit http://localhost:3000/books/new.

   No errors! But we still have a blank page. Let’s start building out that form.

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

2. Inside the form_for block, add the following:

   <ul>
     <li>
       <%= f.label :title %>
       <%= f.text_field :title %>
     </li>
   
     <li>
       <%= f.label :author %>
       <%= f.text_field :author %>
     </li>
   </ul>
   

   We’re putting your form elements inside an unordered list. The form will have two fields, one for title and one for author.

   f.label defines labels for each field.

   f.text_field creates a text input field for each field.

3. Save your changes and revisit http://localhost:3000/books/new.

   Can you match the code you added to the different elements on the page?

1. Your new book form has fields for title and author.

   Try adding a field for the price. Remember, we named the field price_cents.

1. What did you come up with? If you followed the pattern used for the other two fields, you probably came up with something like this:

   <li>
     <%= f.label :price_cents %>
     <%= f.text_field :price_cents %>
   </li>
   

   That works well, but price_cents isn’t a text field. It’s a number.

   To make it a number field, simply change

   <%= f.text_field :price_cents %>
   

   to

   <%= f.number_field :price_cents %>
   

2. Your full solution should look like this:

   <li>
     <%= f.label :price_cents %>
     <%= f.number_field :price_cents %>
   </li>
   

   Update your solution, save your changes, and revisit http://localhost:3000/books/new.

   Does the price_cents field differ from other fields on the page?

We have a couple more fields to add to the form. We need fields for quantity and description.

1. Add quantity to your form as a number_field.

2. Add description to your form as a text_area.

   (text_area differs from text_field by offering more space for text - which is useful for long descriptions.)

1. What does your solution look like? Your complete form should look like this:

   <%= form_for(@book) do |f| %>
     <ul>
       <li>
         <%= f.label :title %>
         <%= f.text_field :title %>
       </li>
   
       <li>
         <%= f.label :author %>
         <%= f.text_field :author %>
       </li>
   
       <li>
         <%= f.label :price_cents %>
         <%= f.number_field :price_cents %>
       </li>
   
       <li>
         <%= f.label :quantity %>
         <%= f.number_field :quantity %>
       </li>
   
       <li>
         <%= f.label :description %>
         <%= f.text_area :description %>
       </li>
     </ul>
   <% end %>
   

2. Update your solution to match this solution and save your changes.

Now you have a beautiful form full of fields. You can enter so much book data! 😍

But there’s no way for you to save that data in your application’s database 😞

Don’t worry! We can fix that!

1. At the end of the form_for block`, add the following line:

   <%= f.submit %>
   

   This will add a submission button to your form.

2. Save your changes and revisit http://localhost:3000/books/new.

   f.submit generates a button labeled “Create Book”.

1. Now that you have a form with a shiny “Create Book” button, why don’t you try creating a book?

   Fill out the form and click “Create Book”.

2. Error? ERROR?!

   

   You’re getting an Unknown action error that says “The action ‘create’ could not be found for BooksController”.

   Huh?

   We’ve been working with the BooksController new action? How did we end up with an error for the create action?

1. Go back to Terminal and stop your application’s web server by running Ctrl-C. Then, run rake routes.

2. Take a look at the second row of the routing table.

   POST   /books(.:format)          books#create
   

   Does that look familiar? 😉

   POST requests to /books get sent to the BooksController create action!

   It looks like we were destined to reach the BooksController create action, but how did the form know to go there?

   By default, a form_for with a new record will be wired up to POST requests to its matching create action.

   In our case, we setup form_for with a new book. Therefore, the form was setup to POST to the BooksController create action.

   Does this make sense to you? If it does, I’m impressed. I’m having a hard time understanding it all. 😅

3. Don’t worry if you don’t understand everything that is going on. It will make more sense over time.

   The key take away here is the new book form gets submitted to the BooksController create action.

4. Restart your application’s web server.

1. Open the BooksController in your text editor.

2. Add a create method to the end of the controller.

   def create
   end
   

3. Save your changes and try adding a book again.

   Nothing happens! Hey, it’s better than an error…

1. Add the following code to your BooksController create method:

   Book.create(title: params[:book][:title], author: params[:book][:author], price_cents: params[:book][:price_cents], quantity: params[:book][:quantity], description: params[:book][:description])
   

   We’re using Book.create to create a new book. The new book’s attributes are being set with values from the params hash book key.

2. Save you changes and try adding a book again.

Nothing happened, right?

Not exactly…

1. Go to Terminal and stop your application’s web server.

2. Now, run rails console and get the last book in your database.

   Does it look familiar?

   It’s the book you created!

   Although it looked like nothing happened when you clicked submit, the request made it to the BooksController create action and Book.create was run.

3. The create action is almost done. Now, we just need make the experience a little better.

   Exit rails console and restart your application’s web server.

1. In your text editor, open the BooksController.

2. At the end of the create method, add the following line:

   redirect_to books_path
   

   With this change, you’ll be redirected to the books_path after a new book is created.

   books_path is a Rails helper method. It evaluates to /books or your book index page.

3. Save your changes and revisit http://localhost:3000/books/new.

   Add a new book and you will be redirected to the books index. The new book will show up at the end of the index.

   Magic

   

1. Open the BooksController in your text editor and take a look at the create method.

2. In the first line of the create method, you’re calling Book.create and setting attributes one by one from the params hash.

   Book.create(title: params[:book][:title], author: params[:book][:author], price_cents: params[:book][:price_cents], quantity: params[:book][:quantity], description: params[:book][:description])
   

   Do you notice a pattern in the attributes that are being set?

   Every attribute that you’re setting is in params[:book].

   title: params[:book][:title]
   author: params[:book][:author]
   price_cents: params[:book][:price_cents]
   ...
   

   Since every attribute you’re setting is in params[:book], we can simplify that line.

3. Change Book.create from

   Book.create(title: params[:book][:title], author: params[:book][:author], price_cents: params[:book][:price_cents], quantity: params[:book][:quantity], description: params[:book][:description])
   

   to

   Book.create(params[:book])
   

4. Save your changes, revisit http://localhost:3000/books/new, and try creating a book.

1. Reopen your BooksController.

2. To use strong parameters, change Book.create from

   Book.create(params[:book])
   

   to

   Book.create(params.require(:book).permit(:title, :author, :price_cents, :quantity, :description)
   

   When we want to create a book from the params hash, the params hash must have a book hash. From the book hash, we’ll get any of the permitted attributes and assign them to the new book.

3. Save your changes, revisit http://localhost:3000/books/new, and try creating a book again.

To create books in the browser, you’ve been going directly to http://localhost:3000/books/new. That works, but it isn’t very convenient.

Let’s add a link to the book index that will take us to http://localhost:3000/books/new.

1. Open app/view/books/index.html.erb in your text editor.

2. After the unordered list, add the following line:

   <%= link_to("Add a book", new_book_path) %>
   

   We’re using the link_to helper to create a link. The link’s text will be “Add a book”, and it will link to the new_book_path (/books/new).

3. Save your changes and go to http://localhost:3000/books/new.

   You should see the new link. Clicking it should take you to the new book form.

Now you can add all the books you heart desires from the comfort of your browser.

1. When you’re done adding books and basking in the glory, stop your application’s web server and give yourself a high five.