file_upload.pt

<tal:block tal:define="oid oid|field.oid;
                       css_class css_class|field.widget.css_class;
                       style style|field.widget.style;">
  ${field.start_mapping()}
  <input type="file" name="upload" id="${oid}"
         tal:attributes="style style;
                         accept accept|field.widget.accept;
                         data-filename cstruct.get('filename');
                         attributes|field.widget.attributes|{};"/>
  <input tal:define="uid cstruct.get('uid')"
         tal:condition="uid"
         type="hidden" name="uid" value="${uid}"/>
  ${field.end_mapping()}
  <script type="text/javascript">
    deform.addCallback('${oid}', function (oid) {
      $('#' + oid).upload();
    });
  </script>
</tal:block>