old_contents: from django.db import models
  from django.utils.translation import gettext_lazy as _
  
  
  class CurrencyManager(models.Manager):
      def active(self):
          return self.get_query_set().filter(is_active=True)
  
  
  class Currency(models.Model):
      code = models.CharField(_('code'), max_length=3)
      name = models.CharField(_('name'), max_length=35)
      symbol = models.CharField(_('symbol'), max_length=4, blank=True)
      factor = models.DecimalField(_('factor'), max_digits=30, decimal_places=10,
          help_text=_('Specifies the difference of the currency to default one.'))
      is_active = models.BooleanField(_('active'), default=True,
          help_text=_('The currency will be available.'))
      is_base = models.BooleanField(_('base'), default=False,
          help_text=_('Make this the base currency against which rates are calculated.'))
      is_default = models.BooleanField(_('default'), default=False,
          help_text=_('Make this the default user currency.'))
  
      objects = CurrencyManager()
  
      class Meta:
          ordering = ('name', )
          verbose_name = _('currency')
          verbose_name_plural = _('currencies')
  
      def __unicode__(self):
          return self.code
  
      def save(self, **kwargs):
          # Make sure the base and default currencies are unique
          if self.is_base:
              Currency.objects.filter(is_base=True).update(is_base=False)
          if self.is_default:
              Currency.objects.filter(is_default=True).update(is_default=False)
          super(Currency, self).save(**kwargs)
  
      def to_base(self, price):
          from . import utils
          return utils.price_to_base(price, self)
  
      @classmethod
      def price_to_base(cls, price, code):
          return cls.objects.get(code__exact=code).to_base(price)
  
new_contents: from django.db import models
  from django.utils.translation import gettext_lazy as _
  
  
  class CurrencyManager(models.Manager):
      def active(self):
          return self.get_queryset().filter(is_active=True)
  
  
  class Currency(models.Model):
      code = models.CharField(_('code'), max_length=3)
      name = models.CharField(_('name'), max_length=35)
      symbol = models.CharField(_('symbol'), max_length=4, blank=True)
      factor = models.DecimalField(_('factor'), max_digits=30, decimal_places=10,
          help_text=_('Specifies the difference of the currency to default one.'))
      is_active = models.BooleanField(_('active'), default=True,
          help_text=_('The currency will be available.'))
      is_base = models.BooleanField(_('base'), default=False,
          help_text=_('Make this the base currency against which rates are calculated.'))
      is_default = models.BooleanField(_('default'), default=False,
          help_text=_('Make this the default user currency.'))
  
      objects = CurrencyManager()
  
      class Meta:
          ordering = ('name', )
          verbose_name = _('currency')
          verbose_name_plural = _('currencies')
  
      def __unicode__(self):
          return self.code
  
      def save(self, **kwargs):
          # Make sure the base and default currencies are unique
          if self.is_base:
              Currency.objects.filter(is_base=True).update(is_base=False)
          if self.is_default:
              Currency.objects.filter(is_default=True).update(is_default=False)
          super(Currency, self).save(**kwargs)
  
      def to_base(self, price):
          from . import utils
          return utils.price_to_base(price, self)
  
      @classmethod
      def price_to_base(cls, price, code):
          return cls.objects.get(code__exact=code).to_base(price)
  
subject: fix for dj1.8 compatibility