forum/models/tag.py

   1 import datetime
   2 from base import *
   3
   4 from django.conf import settings as django_settings
   5 from django.core.cache.backends.base import BaseCache
   6 from django.utils.translation import ugettext as _
   7 from django.utils.encoding import smart_unicode, force_unicode
   8
   9 from forum import modules
  10
  11 class ActiveTagManager(CachedManager):
  12     use_for_related_fields = True
  13
  14     def get_queryset(self):
  15         return super(ActiveTagManager, self).get_queryset().exclude(used_count__lt=1)
  16
  17 class Tag(BaseModel):
  18     name            = models.CharField(max_length=255, unique=True)
  19     created_by      = models.ForeignKey(User, related_name='created_tags')
  20     created_at      = models.DateTimeField(default=datetime.datetime.now, blank=True, null=True)
  21     marked_by       = models.ManyToManyField(User, related_name="marked_tags", through="MarkedTag")
  22     # Denormalised data
  23     used_count = models.PositiveIntegerField(default=0)
  24
  25     active = ActiveTagManager()
  26
  27     class Meta:
  28         ordering = ('-used_count', 'name')
  29         app_label = 'forum'
  30
  31     def __unicode__(self):
  32         return force_unicode(self.name)
  33
  34     def add_to_usage_count(self, value):
  35         if self.used_count + value < 0:
  36             self.used_count = 0
  37         else:
  38             self.used_count = models.F('used_count') + value
  39
  40     def cache_key(self):
  41         return self._generate_cache_key(Tag.safe_cache_name(self.name))
  42
  43     @classmethod
  44     def safe_cache_name(cls, name):
  45         return "".join([str(ord(c)) for c in name])
  46
  47     @classmethod
  48     def infer_cache_key(cls, querydict):
  49         if 'name' in querydict:
  50             cache_key = cls._generate_cache_key(cls.safe_cache_name(querydict['name']))
  51
  52             if len(cache_key) > django_settings.CACHE_MAX_KEY_LENGTH:
  53                 cache_key = cache_key[:django_settings.CACHE_MAX_KEY_LENGTH]
  54
  55             return cache_key
  56
  57         return None
  58
  59     @classmethod
  60     def value_to_list_on_cache_query(cls):
  61         return 'name'
  62
  63     @models.permalink
  64     def get_absolute_url(self):
  65         return ('tag_questions', (), {'tag': self.name})
  66
  67 class MarkedTag(models.Model):
  68     TAG_MARK_REASONS = (('good', _('interesting')), ('bad', _('ignored')))
  69     tag = models.ForeignKey(Tag, related_name='user_selections')
  70     user = models.ForeignKey(User, related_name='tag_selections')
  71     reason = models.CharField(max_length=16, choices=TAG_MARK_REASONS)
  72
  73     class Meta:
  74         app_label = 'forum'
  75