I'm not sure about using Foreingkey attribute here.
But how about this?
class UploadedOrderImage(models.Model):
order_image = models.OneToOneField(OrderImage)
image_large = models.ImageField(upload_to=get_file_path_random)
image_thumb = models.ImageField(upload_to=get_file_path_thumb)
def save(self):
super(UploadedOrderImage, self).save()
if self.image_large:
image = Image.open(self.image_large)
size = (self.order_image.image_large_height,self.order_image.image_large_height)
image = image.resize(size, Image.ANTIALIAS)
image.save(self.image_large.path)
if self.image_thumb:
image = Image.open(self.image_thumb)
size = (self.order_image.image_thumb_height,self.order_image.image_thumb_height)
image = image.resize(size, Image.ANTIALIAS)
image.save(self.image_thumb.path)