be made visible. If there is at least one mandatory enabling condition

    defined on a Product or Category, it will only be enabled if *all*

    mandatory conditions are met, otherwise, if there is at least one enabling

    condition defined on a Product or Category, it will only be enabled if at

    least one condition is met. '''

    objects = InheritanceManager()

    def __str__(self):

        return self.description

class TimeOrStockLimitFlag(EnablingConditionBase):

    ''' Registration product ceilings '''

    class Meta:

    start_time = models.DateTimeField(

        null=True,

        blank=True,

        help_text=_("Products included in this condition will only be "

                    "available after this time."),

@python_2_unicode_compatible

class ProductFlag(EnablingConditionBase):

    ''' The condition is met because a specific product is purchased. '''

    def __str__(self):

        return "Enabled by products: " + str(self.enabling_products.all())

    enabling_products = models.ManyToManyField(

        Product,

        help_text=_("If one of these products are purchased, this condition "

@python_2_unicode_compatible

class CategoryFlag(EnablingConditionBase):

    ''' The condition is met because a product in a particular product is

    purchased. '''

    def __str__(self):

        return "Enabled by product in category: " + str(self.enabling_category)

    enabling_category = models.ForeignKey(

        Category,

        help_text=_("If a product from this category is purchased, this "

@python_2_unicode_compatible

class VoucherFlag(EnablingConditionBase):

    ''' The condition is met because a Voucher is present. This is for e.g.

    enabling sponsor tickets. '''

    def __str__(self):

        return "Enabled by voucher: %s" % self.voucher

    voucher = models.OneToOneField(Voucher)