class Tag(models.Model):
    """
    Defines a tag for any model object.
    """
    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey()
    type = models.ForeignKey(TagType, related_name='+', verbose_name="Typ", db_column='Typ')
    value = models.CharField("Wert", max_length=80, db_column='Wert')

class TaggedMixin(models.Model):
    """ Mixed into a model class, provides it with the ability to receive tags
    (i.e. Tag objects).
    """
    _tags = GenericRelation(Tag)