app/views/search/_promise_results.html.erb
<h3><%= Promise.model_name.human(count: 2).capitalize %></h3>
<ul>
<% results.group_by { |e| e.party_names.to_sentence }.each do |party_names, promises| %>
<% promises.each do |promise| %>
<li>
<%= link_to promise.body, promise_path(promise._id), class: 'promise-link' %>
<span class="muted">(<%= promise.parliament_period_name %>)</span>
</li>
<% end %>
<% end %>
</ul>