======================
Tuesday, June 30, 2015
======================

More testing and documentation after :ticket:`173` (Class-based
permission control (UserRoles)).

Analyzing some server reports after release in Eupen:


UnicodeEncodeError at /callbacks/140565193883152/yes
====================================================

Diese Meldung ist eine Nebenwirkung der Mörderfalle. Sie kommt
scheinbar, wenn jemand einen Auszug direkt manuell zu löschen versucht
statt den Button "Cache löschen" des ausgedruckten Objekts zu
verwenden. 

Not sure whether the UnicodeDecodeError happens only on Python
2.6. This would be a reason to upgrade their Python to 2.7.

Or a reason for me to install Python 2.6 (thanks to `d3vid
<http://askubuntu.com/questions/125342/how-can-i-install-python-2-6-on-12-04>`__)
who asked about this on askubuntu.com::

  $ sudo add-apt-repository ppa:fkrull/deadsnakes
  $ sudo apt-get update
  $ sudo apt-get install python2.6

Unfortunately I still could not reproduce my customer's traceback.
Maybe because they have Python 2.6.6 while above trick installed
Python 2.6.9.


Setting ForeignKeys to NULL when deleting an object
===================================================

Lino now supports ForeignKey fields with `on_delete
<https://docs.djangoproject.com/en/5.0/ref/models/fields/#django.db.models.ForeignKey.on_delete>`_
set to `SET_NULL`.  First use case is the :attr:`printed_by
<lino.modlib.excerpts.mixins.Certifiable.printed_by>` field of a
:class:`Certifiable <lino.modlib.excerpts.mixins.Certifiable>`.

Until now, manually deleting a certifying excerpt failed with the
message "Cannot delete Excerpt XYZ because 1 contract refers to it".
Okay, the workaround was easy: just use the clear_cache action on the
certified object.  But direct deletion should not fail just because of
that nullable :attr:`printed_by
<lino.modlib.excerpts.mixins.Certifiable.printed_by>` pointer.

BTW :meth:`delete_veto_message
<lino.core.model.Model.delete_veto_message>` message now includes the
model's verbose name because the `unicode` of a database object does
not (and should not) mention it.

Three "quick wins"
==================

"Im Bereich Person, den Namen des Datenfelds "Anrede" durch "Titel" ersetzen"

This would have been a quick one, but I discovered that this field was
being rendered in an inconsistent way (sometimes before and sometimes
after the salutation).

I moved it from :class:`Person <lino.modlib.contacts.models.Person>`
to :class:`lino.mixins.human.Human`, updated documentation and added
some test cases in :ref:`lino.tutorial.human`.