Iterating over an association in_groups_of (i.e. "wrapper every X items")

[Timothy Spangler]

I have a HABTM association connecting Users to Languages. I am using simple_fields_for and accepts_nested_attributes_for to allow my UserInfo form to accept languages for the association.

My goal is to display a checkbox for each language, nicely aligned and following Bootstrap conventions. I've tried this:

<%= f.simple_fields_for :user do |fields| %>

  <%= fields.association :languages, as: :check_boxes, label_method: :english_and_native_name, label: 'Languages spoken', wrapper_html: {class: 'row'}, item_wrapper_tag: 'span', item_wrapper_class: 'col-md-4' %>

<% end %>

Of course, this only ever creates one row tag (the collection wrapper), and as such the boxes don't stack nicely and everything gets thrown off, especially the collection label ("Languages spoken").

What I need is to create a new row every 3 languages, which led me to something more along the lines of this:

<% Language.all.in_groups_of(3, false) do |languages| %>

  <div class="row">

    <% languages.each do |language| %>

      <div class="col-md-4">

        <span class="checkbox">

          <%= fields.label :language_ids, language.english_and_native_name do %>

            <%= fields.check_box :language_ids %>

            <%= language.english_and_native_name %>

          <% end %>

        </span>

      </div>

    <% end %>

  </div>    

<% end %>

This creates a perfectly aligned grid of checkboxes, but with the wrong names and values:

<div class="col-md-4">

  <span class="checkbox">

    <label for="user_info_user_attributes_language_ids">

      <input name="user_info[user_attributes][language_ids]" type="hidden" value="0"><input type="checkbox" value="1" name="user_info[user_attributes][language_ids]" id="user_info_user_attributes_language_ids">Japanese (日本語)

    </label>

  </span>

</div>

What is the most SimpleForm-appropriate way to do what I'm trying to do?