[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.

Schema of the data
------------------

First take a look at the data schema_ then try to remember that you are browsing
through a heap of data by applying stylesheets to the results of queries. This
site is not a content management system with items placed in folders. It is an
interface to a database which applies a view to retreived data.

.. _schema: schema