app/views/cms/custom_fields/_date.html.erb
<%= render :layout => 'cms/custom_fields/article_custom_field_template', locals: { field: field } do %>
<div class='custom-field-label'>
<span><%= field[:name].humanize %>:</span>
</div>
<div class='custom-field-content'>
<%= text_field_tag("article[metadata][custom_fields][#{field[:name].to_slug}][value]",
field[:value], placeholder: Date.current, class: 'custom-datepicker') %>
</div>
<% end %>