project/cmsplugin_contact_plus/inline_ordering/models.py

   1 from django.db import models
   2
   3 class Orderable(models.Model):
   4
   5     """Add extra field and default ordering column for and inline orderable model"""
   6
   7     inline_ordering_position = models.IntegerField(blank = True,
   8                                                    null = True,
   9                                                    editable = True)
  10
  11     class Meta:
  12         abstract = True
  13         ordering = ('inline_ordering_position',)
  14
  15     def save(self, force_insert=False, force_update=False, using=None):
  16         """Calculate position (max+1) for new records"""
  17         if not self.inline_ordering_position:
  18             max = self.__class__.objects.filter().aggregate(models.Max('inline_ordering_position'))
  19             try:
  20                 self.inline_ordering_position = max['inline_ordering_position__max'] + 1
  21             except TypeError:
  22                 self.inline_ordering_position = 1
  23         return super(Orderable, self).save(force_insert=force_insert, force_update=force_update, using=using)