Question

Rails 3.0 deprecated f.error_messages and now requires a plugin to work correctly – I however want to learn how to display error messages the (new) native way. I am following the getting started guide, which uses the deprecated method when implementing the comments form. For example:

<h2>Add a comment:</h2>
<%= form_for([@post, @post.comments.build]) do |f| %>
  <%= f.error_messages %>
<div class="field">
  <% f.label :commenter  %><br />
  <%= f.text_field :commenter  %>
</div>
<div class="field">
  <%= f.label :body %><br />
  <%= f.text_area :body %>
</div>
<div class="actions">
  <%= f.submit %>
</div>
<% end %>

Here is the correct way to do it (as generated by the scaffold):

<%= form_for(@post) do |f| %>
  <% if @post.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@post.errors.count, "error") %> prohibited this post from being saved:</h2>

      <ul>
      <% @post.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>
 . . . 

I understand that I use the @post variable in the latter example, but what variable do I reference in the former to get the error messages for comment creation?

Answer 1

I just looked into the docrails github issues, and they’ve decided to remove f.error_messages instead of explaining how to do validation for comments.