--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/web/lib/tagging/models.py Fri Jan 22 18:23:34 2010 +0100
@@ -0,0 +1,490 @@
+"""
+Models and managers for generic tagging.
+"""
+# Python 2.3 compatibility
+try:
+ set
+except NameError:
+ from sets import Set as set
+
+from django.contrib.contenttypes import generic
+from django.contrib.contenttypes.models import ContentType
+from django.db import connection, models
+from django.db.models.query import QuerySet
+from django.utils.translation import ugettext_lazy as _
+
+from tagging import settings
+from tagging.utils import calculate_cloud, get_tag_list, get_queryset_and_model, parse_tag_input
+from tagging.utils import LOGARITHMIC
+
+qn = connection.ops.quote_name
+
+############
+# Managers #
+############
+
+class TagManager(models.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]
+
+ # 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):
+ TaggedItem._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)
+ TaggedItem._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)
+ TaggedItem._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 _get_usage(self, model, counts=False, min_count=None, extra_joins=None, extra_criteria=None, params=None):
+ """
+ Perform the custom SQL query for ``usage_for_model`` and
+ ``usage_for_queryset``.
+ """
+ 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(TaggedItem._meta.db_table),
+ 'model': model_table,
+ 'model_pk': model_pk,
+ 'content_type_id': ContentType.objects.get_for_model(model).pk,
+ }
+
+ min_count_sql = ''
+ 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 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 = {}
+
+ queryset = model._default_manager.filter()
+ for f in filters.items():
+ queryset.query.add_filter(f)
+ usage = self.usage_for_queryset(queryset, counts, min_count)
+
+ return usage
+
+ def usage_for_queryset(self, queryset, counts=False, min_count=None):
+ """
+ Obtain a list of tags associated with instances of a model
+ contained in the given queryset.
+
+ 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``.
+ """
+
+ if getattr(queryset.query, 'get_compiler', None):
+ # Django 1.2+
+ compiler = queryset.query.get_compiler(using='default')
+ extra_joins = ' '.join(compiler.get_from_clause()[0][1:])
+ where, params = queryset.query.where.as_sql(
+ compiler.quote_name_unless_alias, compiler.connection
+ )
+ else:
+ # Django pre-1.2
+ extra_joins = ' '.join(queryset.query.get_from_clause()[0][1:])
+ where, params = queryset.query.where.as_sql()
+
+ if where:
+ extra_criteria = 'AND %s' % where
+ else:
+ extra_criteria = ''
+ return self._get_usage(queryset.model, counts, min_count, extra_joins, extra_criteria, params)
+
+ 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(TaggedItem._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)
+
+class TaggedItemManager(models.Manager):
+ """
+ FIXME There's currently no way to get the ``GROUP BY`` and ``HAVING``
+ SQL clauses required by many of this manager's methods into
+ Django's ORM.
+
+ For now, we manually execute a query to retrieve the PKs of
+ objects we're interested in, then use the ORM's ``__in``
+ lookup to return a ``QuerySet``.
+
+ Now that the queryset-refactor branch is in the trunk, this can be
+ tidied up significantly.
+ """
+ def get_by_model(self, queryset_or_model, tags):
+ """
+ Create a ``QuerySet`` containing instances of the specified
+ 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
+ queryset, model = get_queryset_and_model(queryset_or_model)
+ 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(queryset_or_model, tags)
+
+ queryset, model = get_queryset_and_model(queryset_or_model)
+ content_type = ContentType.objects.get_for_model(model)
+ opts = self.model._meta
+ tagged_item_table = qn(opts.db_table)
+ return queryset.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=[content_type.pk, tag.pk],
+ )
+
+ def get_intersection_by_model(self, queryset_or_model, tags):
+ """
+ Create a ``QuerySet`` containing instances of the specified
+ model associated with *all* of the given list of tags.
+ """
+ tags = get_tag_list(tags)
+ tag_count = len(tags)
+ queryset, model = get_queryset_and_model(queryset_or_model)
+
+ if not tag_count:
+ return model._default_manager.none()
+
+ 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 queryset.filter(pk__in=object_ids)
+ else:
+ return model._default_manager.none()
+
+ def get_union_by_model(self, queryset_or_model, tags):
+ """
+ Create a ``QuerySet`` containing instances of the specified
+ model associated with *any* of the given list of tags.
+ """
+ tags = get_tag_list(tags)
+ tag_count = len(tags)
+ queryset, model = get_queryset_and_model(queryset_or_model)
+
+ if not tag_count:
+ return model._default_manager.none()
+
+ 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 queryset.filter(pk__in=object_ids)
+ else:
+ return model._default_manager.none()
+
+ def get_related(self, obj, queryset_or_model, num=None):
+ """
+ Retrieve a list of instances of the specified 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.
+ """
+ queryset, model = get_queryset_and_model(queryset_or_model)
+ 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,
+ # Hardcoding this for now just to get tests working again - this
+ # should now be handled by the query object.
+ 'limit_offset': num is not None and 'LIMIT %s' or '',
+ }
+
+ cursor = connection.cursor()
+ params = [obj.pk]
+ if num is not None:
+ params.append(num)
+ cursor.execute(query, params)
+ 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 = queryset.in_bulk(object_ids)
+ return [object_dict[object_id] for object_id in object_ids \
+ if object_id in object_dict]
+ else:
+ return []
+
+##########
+# Models #
+##########
+
+class Tag(models.Model):
+ """
+ A tag.
+ """
+ name = models.CharField(_('name'), max_length=50, unique=True, db_index=True)
+
+ objects = TagManager()
+
+ class Meta:
+ ordering = ('name',)
+ verbose_name = _('tag')
+ verbose_name_plural = _('tags')
+
+ def __unicode__(self):
+ return self.name
+
+class TaggedItem(models.Model):
+ """
+ Holds the relationship between a tag and the item being tagged.
+ """
+ tag = models.ForeignKey(Tag, verbose_name=_('tag'), related_name='items')
+ content_type = models.ForeignKey(ContentType, verbose_name=_('content type'))
+ object_id = models.PositiveIntegerField(_('object id'), db_index=True)
+ object = generic.GenericForeignKey('content_type', 'object_id')
+
+ objects = TaggedItemManager()
+
+ class Meta:
+ # Enforce unique tag association per object
+ unique_together = (('tag', 'content_type', 'object_id'),)
+ verbose_name = _('tagged item')
+ verbose_name_plural = _('tagged items')
+
+ def __unicode__(self):
+ return u'%s [%s]' % (self.object, self.tag)