philo/models/collections.py

   1 from django.contrib.contenttypes import generic
   2 from django.contrib.contenttypes.models import ContentType
   3 from django.db import models
   4
   5 from philo.models.base import value_content_type_limiter, register_value_model
   6 from philo.utils import fattr
   7
   8
   9 __all__ = ('Collection', 'CollectionMember')
  10
  11
  12 class Collection(models.Model):
  13         """
  14         Collections are curated ordered groupings of arbitrary models.
  15
  16         """
  17         #: :class:`CharField` with max_length 255
  18         name = models.CharField(max_length=255)
  19         #: Optional :class:`TextField`
  20         description = models.TextField(blank=True, null=True)
  21
  22         @fattr(short_description='Members')
  23         def get_count(self):
  24                 """Returns the number of items in the collection."""
  25                 return self.members.count()
  26
  27         def __unicode__(self):
  28                 return self.name
  29
  30         class Meta:
  31                 app_label = 'philo'
  32
  33
  34 class CollectionMemberManager(models.Manager):
  35         use_for_related_fields = True
  36
  37         def with_model(self, model):
  38                 """
  39                 Given a model class or instance, returns a queryset of all instances of that model which have collection members in this manager's scope.
  40
  41                 Example::
  42
  43                         >>> from philo.models import Collection
  44                         >>> from django.contrib.auth.models import User
  45                         >>> collection = Collection.objects.get(name="Foo")
  46                         >>> collection.members.all()
  47                         [<CollectionMember: Foo - user1>, <CollectionMember: Foo - user2>, <CollectionMember: Foo - Spam & Eggs>]
  48                         >>> collection.members.with_model(User)
  49                         [<User: user1>, <User: user2>]
  50
  51                 """
  52                 return model._default_manager.filter(pk__in=self.filter(member_content_type=ContentType.objects.get_for_model(model)).values_list('member_object_id', flat=True))
  53
  54
  55 class CollectionMember(models.Model):
  56         """
  57         The collection member model represents a generic link from a :class:`Collection` to an arbitrary model instance with an attached order.
  58
  59         """
  60         #: A :class:`CollectionMemberManager` instance
  61         objects = CollectionMemberManager()
  62         #: :class:`ForeignKey` to a :class:`Collection` instance.
  63         collection = models.ForeignKey(Collection, related_name='members')
  64         #: The numerical index of the item within the collection (optional).
  65         index = models.PositiveIntegerField(verbose_name='Index', help_text='This will determine the ordering of the item within the collection. (Optional)', null=True, blank=True)
  66         member_content_type = models.ForeignKey(ContentType, limit_choices_to=value_content_type_limiter, verbose_name='Member type')
  67         member_object_id = models.PositiveIntegerField(verbose_name='Member ID')
  68         #: :class:`GenericForeignKey` to an arbitrary model instance.
  69         member = generic.GenericForeignKey('member_content_type', 'member_object_id')
  70
  71         def __unicode__(self):
  72                 return u'%s - %s' % (self.collection, self.member)
  73
  74         class Meta:
  75                 app_label = 'philo'
  76
  77
  78 register_value_model(Collection)