:xdate: 2017-10-18

===========================
Wednesday, October 18, 2017
===========================

Models for newbies documentation
================================

After stumbling over Tim Kholod's nice blogpost `The simple way to
understand Django models <https://arevej.me/django-models/>`__, I
started to write :ref:`dev.models` (which mentions it).

Common accounts
===============

I added two virtual fields to
:class:`lino_xl.lib.accounts.CommonAcccounts`, and added the table to
the Explorer menu.


Connect using a Belgian eID card
================================

I asked Google for "belgian eid python" and found `this page
<http://python-social-auth-docs.readthedocs.io/en/latest/backends/belgium_eid.html>`__
which made me discover `Python Social Auth
<https://github.com/python-social-auth>`__.

It seems that for Belgium it's only `a few lines of code
<https://github.com/python-social-auth/social-core/blob/master/social_core/
backends/belgiumeid.py>`__.

There is also a backend for `Google OpenId, OAuth2, OAuth1, Google+
<https://github.com/python-social-auth/social-core/blob/master/social_core/backends/google.py>`__. That
might be interesting for Hamza who is working on :ticket:`2013`.


FieldDoesNotExist: Event has no field named '_event_type_cache'
===============================================================

Yesterday with Johanna we had an error which happens from time to
time::

  File "/xl/lino_xl/lib/cal/models.py", line 560, in after_ui_save
    super(Event, self).after_ui_save(ar, cw)
  File "/lino/lino/modlib/notify/mixins.py", line 144, in after_ui_save
    ar, self, mt, msg, self.get_change_observers())
  File "/lino/lino/modlib/notify/models.py", line 213, in emit_message
    subject_body = msg_func(user, mm)
  File "/lino/lino/modlib/notify/mixins.py", line 135, in msg
    return (subject, self.get_change_body(ar, cw))
  File "/lino/lino/modlib/notify/mixins.py", line 67, in get_change_body
    items = list(cw.get_updates_html(["_user_cache"]))
  File "/lino/lino/core/diff.py", line 68, in get_updates_html
    f = self.watched._meta.get_field(k)
  File "/site-packages/django/db/models/options.py", line 619, in get_field
    raise FieldDoesNotExist("%s has no field named '%s'" % (self.object_name, field_name))
  FieldDoesNotExist: Event has no field named '_event_type_cache'

It seems that the :attr:`__dict__` of a Django database object can now
contain additional names used internally by Django.

I didn't write an automatic way to reproduce it, but I now fixed it at
least theoretically, and at least the test suite passes.

Side effect: The :meth:`lino.core.diff.ChangeWatcher.get_updates`
method now sorts its result in order to make it predictable for test
cases.

En passant I fixed another bug :message:`AjaxExceptionResponse
KeyError: u'obj' in request POST /api/tickets/Tickets` which occured
when sending an update notification to a user in German.  Because the
text "{user} created {what}" had been translated to "{user} hat {obj}
erstellt" (`{obj}` instead `{what}`).



New notification mode "silent"
==============================

For :ticket:`2119` I added a new notification mode :attr:`silent
<lino.modlib.notify.choicelists.MailModels.silent>`.

This mode differs from :attr:`never
<lino.modlib.notify.choicelists.MailModels.never>`: "never" means that
you want to get notified, but only in the web interface, not via
E-Mail. The new option "silent" means that notifications are
completely disabled and not even being created.

To be observed. I am not sure whether they really want this.


Cannot query "1Euro-Shop": Must be "Person" instance
====================================================

Lydia had an error message "ValueError: Cannot query "1Euro-Shop":
Must be "Person" instance".  In the virtual fields :attr:`suppliers`
and :attr:`needed_skills` we had to add::

    if not isinstance(self, dd.plugins.faculties.demander_model):
        return ''