app/views/books/_form.html.erb
<%= form_for(@book) do |f| %>
<% if @book.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(@book.errors.count, "error") %> prohibited this book from being saved:</h2>
<ul>
<% @book.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :isbn %><br>
<%= f.text_field :isbn %>
</div>
<div class="field">
<%= f.label :title %><br>
<%= f.text_field :title %>
</div>
<div class="field">
<%= f.label :description %><br>
<%= f.text_area :description %>
</div>
<div class="field">
<%= f.label :pc_image_url %><br>
<%= f.text_field :pc_image_url %>
</div>
<div class="field">
<%= f.label :mb_image_url %><br>
<%= f.text_field :mb_image_url %>
</div>
<div class="field">
<%= f.label :category_id %><br>
<%= f.text_field :category_id %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>