class AbstractAttributeEntity(models.Model):
    """
    Provides an attribute type to enable relationships with other models
    """
    name = models.CharField(_("Name"), max_length=255)
    slug = models.SlugField(
        _("Slug"), max_length=255, unique=False, blank=True)
    type = models.ForeignKey(
        'catalogue.AttributeEntityType', related_name='entities',
        verbose_name=_("Type"))
    def __unicode__(self):
        return self.name
    class Meta:
        abstract = True
        verbose_name = _('Attribute Entity')
        verbose_name_plural = _('Attribute Entities')
    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(self.name)
        super(AbstractAttributeEntity, self).save(*args, **kwargs)
class AbstractAttributeEntityType(models.Model):
    """
    Provides the name of the model involved in an entity relationship
    """
    name = models.CharField(_("Name"), max_length=255)
    slug = models.SlugField(
        _("Slug"), max_length=255, unique=False, blank=True)
    def __unicode__(self):
        return self.name
    class Meta:
        abstract = True
        verbose_name = _('Attribute Entity Type')
        verbose_name_plural = _('Attribute Entity Types')
    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = slugify(self.name)
        super(AbstractAttributeEntityType, self).save(*args, **kwargs)