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