<%- id = "koi-#{ new_uuid }" -%>
<%= f.association attr.to_sym,
  collection: attr.to_s.classify.constantize.scoped,
  include_blank: true,
  input_html: { id: id, style: 'width:550px' } %>

<%= render "koi/admin_crud/form_field_collection_errors", f: f, attr: attr %>

<script type='text/javascript'>
  $(document).ready(function() {$("#<%= id %>").select2(); });
</script>

<%- id = "koi-#{ new_uuid }" -%>
<%= f.association attr.to_sym,
  collection: attr.to_s.classify.constantize.all,
  include_blank: true,
  input_html: { id: id, style: 'width:550px' } %>

<%= render "koi/admin_crud/form_field_collection_errors", f: f, attr: attr %>

<script type='text/javascript'>
  $(document).ready(function() {$("#<%= id %>").select2(); });
</script>

Update multiselect_association form field to be Rails v4 compatible
Update multiselect_association form field to be Rails v4 compatible