Add ModelWithFieldAttributes *before* PolyModel, so that everything does not
become a "ModelWithFieldAttributes" in the Datastore.
The way PolyModel works, each Model class hierarchy is stored in the Datastore
as the class that directly inherited from PolyModel. So, we do not want to
insert ModelWithFieldAttributes *after* PolyModel by inheriting *from*
PolyModel, or everything would just be a ModelWithFieldAttributes in the
Datastore, instead of Person, Work, Group, etc.
"""
22. Using properties on models
Use properties on models just like on any other Python object.
"""
from django.db import models
class Person(models.Model):
first_name = models.CharField(maxlength=30)
last_name = models.CharField(maxlength=30)
def _get_full_name(self):
return "%s %s" % (self.first_name, self.last_name)
def _set_full_name(self, combined_name):
self.first_name, self.last_name = combined_name.split(' ', 1)
full_name = property(_get_full_name)
full_name_2 = property(_get_full_name, _set_full_name)
__test__ = {'API_TESTS':"""
>>> a = Person(first_name='John', last_name='Lennon')
>>> a.save()
>>> a.full_name
'John Lennon'
# The "full_name" property hasn't provided a "set" method.
>>> a.full_name = 'Paul McCartney'
Traceback (most recent call last):
...
AttributeError: can't set attribute
# But "full_name_2" has, and it can be used to initialise the class.
>>> a2 = Person(full_name_2 = 'Paul McCartney')
>>> a2.save()
>>> a2.first_name
'Paul'
"""}