Group items tagged

Developers News Mixer is free and open source software, coded in Python with the Django Web development framework, and uses Facebook Connect for authentication. You can read more about our development process in our report, and find our source at Google Code.

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

usage_for_model

A nice screencast on many to many relationships. Part of a 3 part series on developing a wiki in django.

Practical Django Projects conversion to 1.0 blog