app/views/relations/_edit.html.erb
<div class="relations edit list-editor" data-components="editRelations"
data-editrelations-options='<%= {data: relations_manager_data}.to_json %>'>
<%= f.input :relations_attributes, as: :hidden, input_html: { class: 'relations-value', value: f.object.relations_values.to_json } %>
<div class="relations-list"></div>
<button class="add-new-btn button" title="<%= t 'relations.title.add' %>">
<%= icon 'plus', t('relations.add') %>
</button>
</div>