diff options
Diffstat (limited to 'tagging/managers.py')
| -rw-r--r-- | tagging/managers.py | 476 |
1 files changed, 68 insertions, 408 deletions
diff --git a/tagging/managers.py b/tagging/managers.py index 612c127..51e2473 100644 --- a/tagging/managers.py +++ b/tagging/managers.py @@ -1,408 +1,68 @@ -"""
-Custom managers for generic tagging models.
-"""
-from django.db import connection
-from django.db.models import Manager
-from django.db.models.query import QuerySet, parse_lookup
-from django.contrib.contenttypes.models import ContentType
-from django.utils.translation import ugettext as _
-
-from tagging import settings
-from tagging.utils import calculate_cloud, get_tag_list, parse_tag_input
-from tagging.utils import LOGARITHMIC
-
-# Python 2.3 compatibility
-if not hasattr(__builtins__, 'set'):
- from sets import Set as set
-
-qn = connection.ops.quote_name
-
-class TagManager(Manager):
- def update_tags(self, obj, tag_names):
- """
- Update tags associated with an object.
- """
- ctype = ContentType.objects.get_for_model(obj)
- current_tags = list(self.filter(items__content_type__pk=ctype.pk,
- items__object_id=obj.pk))
- updated_tag_names = parse_tag_input(tag_names)
- if settings.FORCE_LOWERCASE_TAGS:
- updated_tag_names = [t.lower() for t in updated_tag_names]
-
- TaggedItemModel = self._get_related_model_by_accessor('items')
-
- # Remove tags which no longer apply
- tags_for_removal = [tag for tag in current_tags \
- if tag.name not in updated_tag_names]
- if len(tags_for_removal):
- TaggedItemModel._default_manager.filter(content_type__pk=ctype.pk,
- object_id=obj.pk,
- tag__in=tags_for_removal).delete()
-
- # Add new tags
- current_tag_names = [tag.name for tag in current_tags]
- for tag_name in updated_tag_names:
- if tag_name not in current_tag_names:
- tag, created = self.get_or_create(name=tag_name)
- TaggedItemModel._default_manager.create(tag=tag, object=obj)
-
- def add_tag(self, obj, tag_name):
- """
- Associates the given object with a tag.
- """
- tag_names = parse_tag_input(tag_name)
- if not len(tag_names):
- raise AttributeError(_('No tags were given: "%s".') % tag_name)
- if len(tag_names) > 1:
- raise AttributeError(_('Multiple tags were given: "%s".') % tag_name)
- tag_name = tag_names[0]
- if settings.FORCE_LOWERCASE_TAGS:
- tag_name = tag_name.lower()
- tag, created = self.get_or_create(name=tag_name)
- ctype = ContentType.objects.get_for_model(obj)
- TaggedItemModel = self._get_related_model_by_accessor('items')
- TaggedItemModel._default_manager.get_or_create(
- tag=tag, content_type=ctype, object_id=obj.pk)
-
- def get_for_object(self, obj):
- """
- Create a queryset matching all tags associated with the given
- object.
- """
- ctype = ContentType.objects.get_for_model(obj)
- return self.filter(items__content_type__pk=ctype.pk,
- items__object_id=obj.pk)
-
- def usage_for_model(self, model, counts=False, min_count=None, filters=None):
- """
- Obtain a list of tags associated with instances of the given
- Model class.
-
- If ``counts`` is True, a ``count`` attribute will be added to
- each tag, indicating how many times it has been used against
- the Model class in question.
-
- If ``min_count`` is given, only tags which have a ``count``
- greater than or equal to ``min_count`` will be returned.
- Passing a value for ``min_count`` implies ``counts=True``.
-
- To limit the tags (and counts, if specified) returned to those
- used by a subset of the Model's instances, pass a dictionary
- of field lookups to be applied to the given Model as the
- ``filters`` argument.
- """
- if filters is None: filters = {}
- if min_count is not None: counts = True
-
- model_table = qn(model._meta.db_table)
- model_pk = '%s.%s' % (model_table, qn(model._meta.pk.column))
- query = """
- SELECT DISTINCT %(tag)s.id, %(tag)s.name%(count_sql)s
- FROM
- %(tag)s
- INNER JOIN %(tagged_item)s
- ON %(tag)s.id = %(tagged_item)s.tag_id
- INNER JOIN %(model)s
- ON %(tagged_item)s.object_id = %(model_pk)s
- %%s
- WHERE %(tagged_item)s.content_type_id = %(content_type_id)s
- %%s
- GROUP BY %(tag)s.id, %(tag)s.name
- %%s
- ORDER BY %(tag)s.name ASC""" % {
- 'tag': qn(self.model._meta.db_table),
- 'count_sql': counts and (', COUNT(%s)' % model_pk) or '',
- 'tagged_item': qn(self._get_related_model_by_accessor('items')._meta.db_table),
- 'model': model_table,
- 'model_pk': model_pk,
- 'content_type_id': ContentType.objects.get_for_model(model).pk,
- }
-
- extra_joins = ''
- extra_criteria = ''
- min_count_sql = ''
- params = []
- if len(filters) > 0:
- joins, where, params = parse_lookup(filters.items(), model._meta)
- extra_joins = ' '.join(['%s %s AS %s ON %s' % (join_type, table, alias, condition)
- for (alias, (table, join_type, condition)) in joins.items()])
- extra_criteria = 'AND %s' % (' AND '.join(where))
- if min_count is not None:
- min_count_sql = 'HAVING COUNT(%s) >= %%s' % model_pk
- params.append(min_count)
-
- cursor = connection.cursor()
- cursor.execute(query % (extra_joins, extra_criteria, min_count_sql), params)
- tags = []
- for row in cursor.fetchall():
- t = self.model(*row[:2])
- if counts:
- t.count = row[2]
- tags.append(t)
- return tags
-
- def related_for_model(self, tags, model, counts=False, min_count=None):
- """
- Obtain a list of tags related to a given list of tags - that
- is, other tags used by items which have all the given tags.
-
- If ``counts`` is True, a ``count`` attribute will be added to
- each tag, indicating the number of items which have it in
- addition to the given list of tags.
-
- If ``min_count`` is given, only tags which have a ``count``
- greater than or equal to ``min_count`` will be returned.
- Passing a value for ``min_count`` implies ``counts=True``.
- """
- if min_count is not None: counts = True
- tags = get_tag_list(tags)
- tag_count = len(tags)
- tagged_item_table = qn(self._get_related_model_by_accessor('items')._meta.db_table)
- query = """
- SELECT %(tag)s.id, %(tag)s.name%(count_sql)s
- FROM %(tagged_item)s INNER JOIN %(tag)s ON %(tagged_item)s.tag_id = %(tag)s.id
- WHERE %(tagged_item)s.content_type_id = %(content_type_id)s
- AND %(tagged_item)s.object_id IN
- (
- SELECT %(tagged_item)s.object_id
- FROM %(tagged_item)s, %(tag)s
- WHERE %(tagged_item)s.content_type_id = %(content_type_id)s
- AND %(tag)s.id = %(tagged_item)s.tag_id
- AND %(tag)s.id IN (%(tag_id_placeholders)s)
- GROUP BY %(tagged_item)s.object_id
- HAVING COUNT(%(tagged_item)s.object_id) = %(tag_count)s
- )
- AND %(tag)s.id NOT IN (%(tag_id_placeholders)s)
- GROUP BY %(tag)s.id, %(tag)s.name
- %(min_count_sql)s
- ORDER BY %(tag)s.name ASC""" % {
- 'tag': qn(self.model._meta.db_table),
- 'count_sql': counts and ', COUNT(%s.object_id)' % tagged_item_table or '',
- 'tagged_item': tagged_item_table,
- 'content_type_id': ContentType.objects.get_for_model(model).pk,
- 'tag_id_placeholders': ','.join(['%s'] * tag_count),
- 'tag_count': tag_count,
- 'min_count_sql': min_count is not None and ('HAVING COUNT(%s.object_id) >= %%s' % tagged_item_table) or '',
- }
-
- params = [tag.pk for tag in tags] * 2
- if min_count is not None:
- params.append(min_count)
-
- cursor = connection.cursor()
- cursor.execute(query, params)
- related = []
- for row in cursor.fetchall():
- tag = self.model(*row[:2])
- if counts is True:
- tag.count = row[2]
- related.append(tag)
- return related
-
- def cloud_for_model(self, model, steps=4, distribution=LOGARITHMIC,
- filters=None, min_count=None):
- """
- Obtain a list of tags associated with instances of the given
- Model, giving each tag a ``count`` attribute indicating how
- many times it has been used and a ``font_size`` attribute for
- use in displaying a tag cloud.
-
- ``steps`` defines the range of font sizes - ``font_size`` will
- be an integer between 1 and ``steps`` (inclusive).
-
- ``distribution`` defines the type of font size distribution
- algorithm which will be used - logarithmic or linear. It must
- be either ``tagging.utils.LOGARITHMIC`` or
- ``tagging.utils.LINEAR``.
-
- To limit the tags displayed in the cloud to those associated
- with a subset of the Model's instances, pass a dictionary of
- field lookups to be applied to the given Model as the
- ``filters`` argument.
-
- To limit the tags displayed in the cloud to those with a
- ``count`` greater than or equal to ``min_count``, pass a value
- for the ``min_count`` argument.
- """
- tags = list(self.usage_for_model(model, counts=True, filters=filters,
- min_count=min_count))
- return calculate_cloud(tags, steps, distribution)
-
- def _get_related_model_by_accessor(self, accessor):
- """
- Returns the model for the related object accessed by the
- given attribute name.
-
- Since we sometimes need to access the ``TaggedItem`` model
- when managing tagging and the``Tag`` model does not have a
- field representing this relationship, this method is used to
- retrieve the ``TaggedItem`` model, avoiding circular imports
- betweeen the ``models`` and ``managers`` modules.
- """
- for rel_obj in self.model._meta.get_all_related_objects():
- if rel_obj.get_accessor_name() == accessor:
- return rel_obj.model
- raise ValueError(_('Could not find a related object with the accessor "%s".') % accessor)
-
-class TaggedItemManager(Manager):
- def get_by_model(self, model, tags):
- """
- Create a queryset matching instances of the given Model
- associated with a given Tag or list of Tags.
- """
- tags = get_tag_list(tags)
- tag_count = len(tags)
- if tag_count == 0:
- # No existing tags were given
- return model._default_manager.none()
- elif tag_count == 1:
- # Optimisation for single tag - fall through to the simpler
- # query below.
- tag = tags[0]
- else:
- return self.get_intersection_by_model(model, tags)
-
- ctype = ContentType.objects.get_for_model(model)
- opts = self.model._meta
- tagged_item_table = qn(opts.db_table)
- return model._default_manager.extra(
- tables=[opts.db_table],
- where=[
- '%s.content_type_id = %%s' % tagged_item_table,
- '%s.tag_id = %%s' % tagged_item_table,
- '%s.%s = %s.object_id' % (qn(model._meta.db_table),
- qn(model._meta.pk.column),
- tagged_item_table)
- ],
- params=[ctype.pk, tag.pk],
- )
-
- def get_intersection_by_model(self, model, tags):
- """
- Create a queryset matching instances of the given Model
- associated with all the given list of Tags.
-
- FIXME The query currently used to grab the ids of objects
- which have all the tags should be all that we need run,
- using a non-explicit join for the QuerySet returned, as
- in get_by_model, but there's currently no way to get the
- required GROUP BY and HAVING clauses into Django's ORM.
-
- Once the ORM is capable of this, we should have a
- solution which requires only a single query and won't
- have the problem where the number of ids in the IN
- clause in the QuerySet could exceed the length allowed,
- as could currently happen.
- """
- tags = get_tag_list(tags)
- tag_count = len(tags)
- model_table = qn(model._meta.db_table)
- # This query selects the ids of all objects which have all the
- # given tags.
- query = """
- SELECT %(model_pk)s
- FROM %(model)s, %(tagged_item)s
- WHERE %(tagged_item)s.content_type_id = %(content_type_id)s
- AND %(tagged_item)s.tag_id IN (%(tag_id_placeholders)s)
- AND %(model_pk)s = %(tagged_item)s.object_id
- GROUP BY %(model_pk)s
- HAVING COUNT(%(model_pk)s) = %(tag_count)s""" % {
- 'model_pk': '%s.%s' % (model_table, qn(model._meta.pk.column)),
- 'model': model_table,
- 'tagged_item': qn(self.model._meta.db_table),
- 'content_type_id': ContentType.objects.get_for_model(model).pk,
- 'tag_id_placeholders': ','.join(['%s'] * tag_count),
- 'tag_count': tag_count,
- }
-
- cursor = connection.cursor()
- cursor.execute(query, [tag.pk for tag in tags])
- object_ids = [row[0] for row in cursor.fetchall()]
- if len(object_ids) > 0:
- return model._default_manager.filter(pk__in=object_ids)
- else:
- return model._default_manager.none()
-
- def get_union_by_model(self, model, tags):
- """
- Create a queryset matching instances of the given Model
- associated with any of the given list of Tags.
- """
- tags = get_tag_list(tags)
- tag_count = len(tags)
- model_table = qn(model._meta.db_table)
- # This query selects the ids of all objects which have any of
- # the given tags.
- query = """
- SELECT %(model_pk)s
- FROM %(model)s, %(tagged_item)s
- WHERE %(tagged_item)s.content_type_id = %(content_type_id)s
- AND %(tagged_item)s.tag_id IN (%(tag_id_placeholders)s)
- AND %(model_pk)s = %(tagged_item)s.object_id
- GROUP BY %(model_pk)s""" % {
- 'model_pk': '%s.%s' % (model_table, qn(model._meta.pk.column)),
- 'model': model_table,
- 'tagged_item': qn(self.model._meta.db_table),
- 'content_type_id': ContentType.objects.get_for_model(model).pk,
- 'tag_id_placeholders': ','.join(['%s'] * tag_count),
- }
-
- cursor = connection.cursor()
- cursor.execute(query, [tag.pk for tag in tags])
- object_ids = [row[0] for row in cursor.fetchall()]
- if len(object_ids) > 0:
- return model._default_manager.filter(pk__in=object_ids)
- else:
- return model._default_manager.none()
-
- def get_related(self, obj, model, num=None):
- """
- Retrieve instances of ``model`` which share tags with the
- model instance ``obj``, ordered by the number of shared tags
- in descending order.
-
- If ``num`` is given, a maximum of ``num`` instances will be
- returned.
- """
- model_table = qn(model._meta.db_table)
- content_type = ContentType.objects.get_for_model(obj)
- related_content_type = ContentType.objects.get_for_model(model)
- query = """
- SELECT %(model_pk)s, COUNT(related_tagged_item.object_id) AS %(count)s
- FROM %(model)s, %(tagged_item)s, %(tag)s, %(tagged_item)s related_tagged_item
- WHERE %(tagged_item)s.object_id = %%s
- AND %(tagged_item)s.content_type_id = %(content_type_id)s
- AND %(tag)s.id = %(tagged_item)s.tag_id
- AND related_tagged_item.content_type_id = %(related_content_type_id)s
- AND related_tagged_item.tag_id = %(tagged_item)s.tag_id
- AND %(model_pk)s = related_tagged_item.object_id"""
- if content_type.pk == related_content_type.pk:
- # Exclude the given instance itself if determining related
- # instances for the same model.
- query += """
- AND related_tagged_item.object_id != %(tagged_item)s.object_id"""
- query += """
- GROUP BY %(model_pk)s
- ORDER BY %(count)s DESC
- %(limit_offset)s"""
- query = query % {
- 'model_pk': '%s.%s' % (model_table, qn(model._meta.pk.column)),
- 'count': qn('count'),
- 'model': model_table,
- 'tagged_item': qn(self.model._meta.db_table),
- 'tag': qn(self.model._meta.get_field('tag').rel.to._meta.db_table),
- 'content_type_id': content_type.pk,
- 'related_content_type_id': related_content_type.pk,
- 'limit_offset': num is not None and connection.ops.limit_offset_sql(num) or '',
- }
-
- cursor = connection.cursor()
- cursor.execute(query, [obj.pk])
- object_ids = [row[0] for row in cursor.fetchall()]
- if len(object_ids) > 0:
- # Use in_bulk here instead of an id__in lookup, because id__in would
- # clobber the ordering.
- object_dict = model._default_manager.in_bulk(object_ids)
- return [object_dict[object_id] for object_id in object_ids]
- else:
- return model._default_manager.none()
+""" +Custom managers for Django models registered with the tagging +application. +""" +from django.contrib.contenttypes.models import ContentType +from django.db import models + +from tagging.models import Tag, TaggedItem + +class ModelTagManager(models.Manager): + """ + A manager for retrieving tags for a particular model. + """ + def get_query_set(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, *arg, **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) |