20120905
========

Today I solved two very subtle problems: 

- add (in an application) the fields `created` and `modified`
  to `contacts.Partner` using :class:`lino.mixins.CreatedModified`
- imported fields were not disabled on a Partner  

The trick was to override `contacts.Partner` instead of defining a `CpasPartner` mixin.

It is another usage example of our relatively new 
:attr:`lino.Lino.override_modlib_models` in the application's settings::

    override_modlib_models = [
        'contacts.Partner', 
        'contacts.Person', 'contacts.Company',
        'households.Household'
        ]

which required :class:`lino.modlib.contacts.models.Partner` to become overridable::

    class Meta:
        abstract = settings.LINO.is_abstract_model('contacts.Partner')

One difficulty was that this caused a Diamond inheritance structure:

.. graphviz::

   digraph foo {
      "contacts.Partner" -> "contacts.Person";
      "contacts.Partner" -> "contacts.Company";
      "contacts.Partner" -> "pcsw.Partner";
      "contacts.Person" -> "pcsw.Person";
      "contacts.Company" -> "pcsw.Company";
      "pcsw.Partner" -> "pcsw.Person";
      "pcsw.Partner" -> "pcsw.Company";
   }
   

And Django still has a problem with Diamond inheritance 
(see :djangoticket:`10808`).
Here is one visible aspect of the problem:

.. literalinclude:: 0905.py

Because we don't want Lino to require to patch Django, 
I wrote a workaround in :func:`lino.dd.on_class_prepared`.



Lino-Welfare
------------

- Partner haben jetzt zwei neue Felder `created` und `modified`.

- Person hat jetzt (wie geplant) ein neues Feld `is_client`. 
  Mit diesem Feld kann man also eine bestehende Person zu einem ´Klienten machen.
  Folgendes kleines Detail bestätigt, dass das Ganze vom Konzept her stimmt
  (ich hatte ein bisschen Angst, wie Lino das hinkriegen würde, 
  aber er hat das super gemacht):
  
  Wenn ich eine bestehende Person X zu einem Klienten mache, dann *nicht* deren NISS 
  ausfülle, und dann eine zweite Person Y ebenfalls zu einem Klienten machen will, 
  dann kriege ich eine Meldung "AJAX communication failed", und auf dem Server steht::

    Traceback (most recent call last):
      File "t:\hgwork\lino\lino\ui\extjs3\ext_store.py", line 1093, in form2obj
        if f.form2obj(ar.request,instance,form_values,is_new):
      File "t:\hgwork\lino\lino\ui\extjs3\ext_store.py", line 202, in form2obj
        return self.set_value_in_object(request,instance,v)
      File "t:\hgwork\lino\lino\utils\mti.py", line 238, in set_value_in_object
        insert_child(obj,self.child_model)
      File "t:\hgwork\lino\lino\utils\mti.py", line 172, in insert_child
        new_obj.save()
      File "t:\hgwork\welfare\lino_welfare\modlib\pcsw\models.py", line 599, in save
        super(Client,self).save(*args,**kw)
      File "t:\hgwork\lino\lino\modlib\contacts\models.py", line 185, in save
        super(Partner,self).save(*args,**kw)
      File "t:\hgwork\lino\lino\utils\dblogger.py", line 52, in save
        super(DiffingMixin, self).save()
      File "t:\hgwork\lino\lino\mixins\__init__.py", line 262, in save
        super(CreatedModified, self).save(*args, **kwargs)
      File "l:\snapshots\django\django\db\models\base.py", line 476, in save
        self.save_base(using=using, force_insert=force_insert, force_update=force_update)
      File "l:\snapshots\django\django\db\models\base.py", line 564, in save_base
        result = manager._insert([self], fields=fields, return_id=update_pk, using=using, raw=raw)
      File "l:\snapshots\django\django\db\models\manager.py", line 203, in _insert
        return insert_query(self.model, objs, fields, **kwargs)
      File "l:\snapshots\django\django\db\models\query.py", line 1581, in insert_query
        return query.get_compiler(using=using).execute_sql(return_id)
      File "l:\snapshots\django\django\db\models\sql\compiler.py", line 910, in execute_sql
        cursor.execute(sql, params)
      File "l:\snapshots\django\django\db\backends\util.py", line 40, in execute
        return self.cursor.execute(sql, params)
      File "l:\snapshots\django\django\db\backends\sqlite3\base.py", line 337, in execute
        return Database.Cursor.execute(self, query, params)
    IntegrityError: column national_id is not unique

  Das ist genau das, was wir wollen: *ein* Klienten ohne NISS ist okay, 
  aber solange der nicht eine NISS bekommen hat, darf man is_client nicht benutzen.
  
TODO: statt "AJAX communication failed" sollte er zumindest sagen 
"IntegrityError: column national_id is not unique", oder (die Luxus-Version) 
"Kann Person X nicht zu einem Klienten machen, weil Klient Y noch keine NISS bekommen hat"

Aber jetzt erstmal Checkin und Feierabend.