app/views/documents/_form.html.erb
<%= form_for(@document) do |f| %>
<% if @document.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(@document.errors.count, "error") %> prohibited this document from being saved:</h2>
<ul>
<% @document.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :name %><br>
<%= f.text_field :name %>
</div>
<div class="field">
<%= f.label :data %><br>
<%= f.text_field :data %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>