20111210
========

Preparing release 1.3.0
-----------------------

Some last details solved:

- :class:`lino.modlib.links.models.LinksFromThis`.column_names
- removed contacts.RoleType and contacts.Role and adapted demo and std fixtures
- Adapted :func:`lino.apps.dsbe.migrate.migrate_from_1_2_8`

- Note that :class:`lino.apps.dsbe.models.ContactPersons`
  inherits :class:`lino.modlib.links.models.LinksFromThis`
  just to override the label.
  
- Discovered that due to a bug in previous dpy versions
  there were some Upload records on Role and RoleType 
  in the customer's database.
  
- Added unit test case :func:`lino.apps.dsbe.tests.dsbe_demo_tests.test11`
  (Anrede Kontaktperson eines :class:`Vertrags <lino.modlib.jobs.models.Contract>` beim Ausdruck)

New function :func:`lino.utils.mti.create_child`
------------------------------------------------

During the preliminary tests of the database migration
we discovered a subtle but serious 
problem which finally lead to an internal improvement in 
the dpy backup/restore mechanism.

Loading dpy fixtures failed because
there were now more complex dependencies
due to the structure changes around links.Link 
converted from contacts.Role.

When creating a Person, User, Company or JobProvider 
(i.e. the MTI children of Contact),
:lino:`Python fixtures </topics/dpy>` 
generated by :class:`lino.utils.dpy.Serializer` 
used the :func:`lino.utils.mti.insert_child` function.
This required a lookup in Contact.
This lookup wasn't only useless, but it failed when it was about an object 
that hadn't yet been saved.
The :class:`dpy.Deserializer <lino.utils.dpy.Deserializer>` 
usually handles
such errors due to not yet existing related objects 
by "deferring" them and try to save them in a second loop.
But in this case the Exception ocurred 
already during the instantiation and thus wasn't handled by the deserializer.

That's why Python fixtures now use the new function 
:func:`lino.utils.mti.create_child` 
instead of 
:func:`lino.utils.mti.insert_child`.
The new function is documented and tested in :mod:`lino.test_apps.mti.models`