Stock Item Models

class StockItemAttribute(models.Model):
    name = models.CharField(max_length=80)
    slug = models.SlugField(unique=True)
    help_text = models.TextField(null=True, blank=True)

    def __unicode__(self):
        return _(self.name)

class StockItemAttributeValue(models.Model):
    stock_item = models.ForeignKey('StockItem', related_name='attribute_values')
    attribute = models.ForeignKey('StockItemAttribute')
    value = models.CharField(max_length=255)
    unit = models.CharField(max_length=8, choices=ATTRIBUTE_VALUE_UNITS, null=True, blank=True)

    def __unicode__(self):
        return "%s %s" % (self.value, self.unit)

    def display_value(self):
        return "%s %s" % (self.value, self.unit)
        
class StockItem(models.Model):
    package_title = models.CharField(max_length=60, blank=True, null=True, help_text='(ex. 3-pack of T-shirts)', default='Individual Item')
    package_count = models.IntegerField(default=1)
    inventory = models.IntegerField(default=0)
    price = models.DecimalField(
        max_digits=10, 
        decimal_places=2, 
        help_text='All prices in USD. Use this field to override the standard pricing of a product for this sepcific stock item.',
        blank=True,
        null=True,
    )
    on_sale = models.BooleanField(default=False)