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"""
Custom managers for tagging.
"""
from django.db import models
from django.contrib.contenttypes.models import ContentType
from tagging.models import Tag
from tagging.models import TaggedItem
class ModelTagManager(models.Manager):
"""
A manager for retrieving tags for a particular model.
"""
def get_queryset(self):
ctype = ContentType.objects.get_for_model(self.model)
return Tag.objects.filter(
items__content_type__pk=ctype.pk).distinct()
def cloud(self, *args, **kwargs):
return Tag.objects.cloud_for_model(self.model, *args, **kwargs)
def related(self, tags, *args, **kwargs):
return Tag.objects.related_for_model(tags, self.model, *args, **kwargs)
def usage(self, *args, **kwargs):
return Tag.objects.usage_for_model(self.model, *args, **kwargs)
class ModelTaggedItemManager(models.Manager):
"""
A manager for retrieving model instances based on their tags.
"""
def related_to(self, obj, queryset=None, num=None):
if queryset is None:
return TaggedItem.objects.get_related(obj, self.model, num=num)
else:
return TaggedItem.objects.get_related(obj, queryset, num=num)
def with_all(self, tags, queryset=None):
if queryset is None:
return TaggedItem.objects.get_by_model(self.model, tags)
else:
return TaggedItem.objects.get_by_model(queryset, tags)
def with_any(self, tags, queryset=None):
if queryset is None:
return TaggedItem.objects.get_union_by_model(self.model, tags)
else:
return TaggedItem.objects.get_union_by_model(queryset, tags)
class TagDescriptor(object):
"""
A descriptor which provides access to a ``ModelTagManager`` for
model classes and simple retrieval, updating and deletion of tags
for model instances.
"""
def __get__(self, instance, owner):
if not instance:
tag_manager = ModelTagManager()
tag_manager.model = owner
return tag_manager
else:
return Tag.objects.get_for_object(instance)
def __set__(self, instance, value):
Tag.objects.update_tags(instance, value)
def __delete__(self, instance):
Tag.objects.update_tags(instance, None)
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