class Mod(models.Model):

    def get_upload_path(self, filename):
        if self.must_be_in_group :
            upload_path = 'jakas_sciezka/' + filename
        else:
            upload_path = 'inna_sciezka/' + filename

        return upload_path

    group = models.ForeignKey(Group)
    name = models.CharField(max_length=64, unique=True)
    description = models.CharField(max_length=1028)
    slug = models.SlugField(unique=True)
    must_be_in_group = models.BooleanField()
    mod_file = models.FileField(upload_to=get_upload_path)

    def save(self, *args, **kwargs):
        self.slug = slugify(self.name)
        super(Mod, self).save(*args, **kwargs)

    def __str__(self):
        return self.name