[dataimport] backout 6947201033be (related to #2788402)
(and add a try: except to cache the intended error)
The problem actually comes from the ``MassiveObjectStore``
in the ``dataio`` cube, so it should be corrected there.
Here, we only protect it with a ``RuntimeWarning`` so that
the user can see the problem.
``value`` is set to ``None`` (whence to ``NULL`` from
a database standpoint), so that the data can be nevertheless
inserted in the database. However, only the keys present in
``row`` are actually non-'``NULL``'.
The real solution is to work out the issue in ``MassiveObjectStore``
directly.
The current try/except should only be a temporary hack.
<table class="attributeForm" style="width:100%;"
tal:attributes="id tab_id | nothing;
class tab_class | nothing;">
<tr tal:iter="widget lines">
<th class="labelCol" tal:content="structure python:widget.render_label(entity)">attrname</th>
<td tal:define="error python:widget.render_error(entity)" style="width:100%;"
tal:attributes="class python:error and 'error' or nothing">
<div tal:replace="structure error">error message if any</div>
<div tal:replace="structure python:widget.edit_render(entity)" >widget (input, textarea, etc.)</div>
<div tal:replace="structure python:widget.render_help(entity)">format help if any</div>
</td>
</tr>
</table>