Cannot create I18n labels when using accepts_nested_attributes_for

Note: I am using Rails 2.3.10.

Normally, you can use Rails’ I18n system to generate label text.

For example, suppose you have a Person class with a name attribute. And this ERB:
<%= form_for @person do |f| %>
<%= f.label :name %>
<%= f.text_field :name %>
<% end %>

And you’d construct your en.yml like so:
en:
helpers:

label:
  name: “your name”

However, this doesn’t work very well with related objects and accepts_nested_attributes_for. Suppose you have the same Person class as before. And person has_many :activities (likewise, activity belongs_to :person) and accepts_nested_attributes_for :activities.

Now your ERB looks like this:
<%= form_for @person do |f| %>
<%= f.label :name %>
<%= f.text_field :name %>

    <% f.fields_for :activities do |a| %>
            <%= l.label :difficulty %> 
            <%= l.text_field :difficulty %> 
    <% end %>

<% end %>

Various combinations indentation of person / activities / difficulty in my en.yml file didn’t work. So I looked inside rails to see what’s going on.

The relevant code is in actionpack-2.3.10/lib/action_view/helpers/form_helper.rb. The method used is

    def to_label_tag(text = nil, options = {})

on line 758.

And the code doing the work is:

    content = if text.blank?
      i18n_label = I18n.t("helpers.label.#{object_name}.#{method_name}", :default => “”) 
      i18n_label if i18n_label.present? 
    else 
      text.to_s 
    end

The problem is you end up with a set of labels like:

    helpers.label.person[activities_attributes][0].difficulty
    helpers.label.person[activities_attributes][1].difficulty 
    helpers.label.person[activities_attributes][2].difficulty