app/views/json/enumeration/medias.erb
"medias": {
<% unless @medias.empty? -%>
<% last_index = @medias.size - 1 -%>
<% @medias.each_with_index do |media, index| -%>
<%= media.url.to_json %>: {
<%= render('@finding', item: media) -%>
}<% unless index == last_index -%>,<% end -%>
<% end -%>
<% end -%>
},