1. Open Terminal and go to your bookstore directory. Then, run rake routes.

2. Now that we want to edit and update books, a couple of rows in the routing table should stand out.

   First, take a look at the row with edit_book.

   edit_book GET    /books/:id/edit(.:format) books#edit
   

   The path to edit_book is /books/:id/edit. Doesn’t that look a little familiar? You’ve been going to /books/:id to see the details for a given book. Now, you’ll go to /books/:id/edit to edit the given book.

3. Start your application’s web server and go to http://localhost:3000/books. From the index, click the link for why’s (poignant) Guide to Ruby.

   Your browser should have URL of http://localhost:3000/books/1 in its address bar. Edit the URL so it’s http://localhost:3000/books/1/edit to visit the edit path for why’s (poignant) Guide to Ruby. Now, try going to the new URL.

You’re getting an Unknown action error because your BooksController doesn’t have an edit method. Let’s add it.

1. Open the BooksController in your text editor. Add the edit method to the end of the controller.

   def edit
   end
   

2. Try going to http://localhost:3000/books/1/edit again.

   What do you think will happen?

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

2. Run touch app/views/books/edit.html.erb to create the edit book template.

3. Restart your application’s web server and revisit http://localhost:3000/books/1/edit.

   A blank page has never looked better!

In the edit template, we’ll take advantage of forms again. We’ll use them to gather new book data.

Before we add the form to the template, let’s make some of the existing book data available.

1. Open the BooksController and add the following line inside the edit method:

   @book = Book.find(params[:id])
   

   (Doesn’t that look a lot like the show method?)

2. Save your changes.

Let’s start the edit book form by adding a field to edit the book’s title.

1. Open app/views/books/edit.html.erb in your text editor and add the following:

   <%= form_for(@book) do |f| %>
     <ul>
       <li>
         <%= f.label :title %>
         <%= f.text_field :title %>
       </li>
     </ul>
   <% end %>
   

2. Save your changes and revist http://localhost:3000/books/1/edit.

1. Update the form so it has fields for all the book attributes: title, author, price_cents, quantity, and description.

   Use the new book form in app/views/books/new.html.erb as an example.

1. How’s your form look? It 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. Save your changes and revisit http://localhost:3000/books/1/edit.

1. Open app/views/books/edit.html.erb and add a submit button as the last line inside the form_for block.

   <%= f.submit %>
   

   This will add a button to your form labeled “Update Book”. Magic

2. Save your changes and revisit http://localhost:3000/books/1/edit. Try making a change and submitting the form.

We’ve been through this drill before…

1. Open the BooksController and add an update method to the end of it.

2. Save your changes and revisit http://localhost:3000/books/1/edit. Try making a change to the book and submitting the form.

Nothing happened!

The form is being submitted to the BooksController update method, and the method is…empty. I think I’d be more surprised if something did happen. 😉

The update method should probably do something. Maybe it should update the book.

1. First, let’s find the book you’re trying to update.

   Open the BooksController and add the following line insided the update method:

   book = Book.find(params[:id])
   

   We’ve done this in a few of the BooksController methods.

   Now that we have the book, how will we update it?

   You’ve updated books before. Do you remember when you added descriptions to all your books? How did you do it?

   You did something along the lines of my_first_book.update(description: "Woooo").

   You called the update method on each of your books to give them descriptions. We’ll use update again to make the requested changes.

2. We could simply do book.update(params[:book]), but that won’t work because of strong parameters.

   Instead, add the following line to the end of the BooksController update method.

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

3. Save your changes, revisit http://localhost:3000/books/1/edit, make some changes, and submit that form!

1. At the end of the BooksController update method, add the following line:

   redirect_to book_path(book)
   

2. Save your changes, revisit http://localhost:3000/books/1/edit, and try making another change. When you submit your changes, you should be redirected to the first book’s details. Keep an out to see your changes.

1. Open the BooksController in your text editor, and add the following code to the end of it:

   def book_params
     params.require(:book).permit(:title, :author, :price_cents, :quantity, :description)
   end
   

   By defining a new book_params method, we have one place to deal with getting and authorizing book params.

2. Now, update the create method so it uses book_params. Change

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

   to

   Book.create(book_params)
   

3. Make the same change to the update method.

4. Save your changes and try creating and editing books. Everything should still work the same as it did before these changes.

Let’s make one more change to improve the edit workflow.

Right now, you can only edit books if you know the edit_book_path URL. Let’s make this a little user-friendly by adding a link to the edit page from the book show page.

1. Open app/views/books/show.html.erb in your text editor. Add the following line to the end of the file:

   <%= link_to "Edit book", edit_book_path(@book) %>
   

   This will create a link with text “Edit book”. It will link to the edit_book_path for @book which will evaluate to /books/:id/edit.

   Adding the link here works really well because we already have the book we want to edit as @book.

2. Save your changes and visit a few books. Clicking the “Edit book” link should take you to the edit page for the book you’re viewing.

3. When you’re done exploring, stop your application’s web server.