用DateField创建对象时使用DateField的Django

Question

我对Django的get_or_create有一个问题，当我创建相同日期的相同对象时，会弹出完整性错误。

我的模型中有如下字段。

class Cart(models.Model):
    created = models.DateTimeField(
        pgettext_lazy('Cart field', 'created'), auto_now_add=True)
    last_status_change = models.DateTimeField(
        pgettext_lazy('Cart field', 'last status change'), auto_now_add=True)
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL, blank=True, null=True, related_name='carts',
        verbose_name=pgettext_lazy('Cart field', 'user'))
    email = models.EmailField(
        pgettext_lazy('Cart field', 'email'), blank=True, null=True)

    def add(self,hoarding, date_from, date_until):
        cart_line, created = self.lines.get_or_create(
            hoarding=hoarding,date_from=date_from,date_until=date_until)



class Meta:
        ordering = ('-last_status_change',)
        verbose_name = pgettext_lazy('Cart model', 'Cart')
        verbose_name_plural = pgettext_lazy('Cart model', 'Carts')

    def __str__(self):
        return smart_str(self.user)


class CartLine(models.Model):
    cart = models.ForeignKey(
        Cart, related_name='lines',
        verbose_name=pgettext_lazy('Cart line field', 'cart'))

    hoarding = models.ForeignKey(
        Hoarding, related_name='+',blank=True, null=True,
        verbose_name=pgettext_lazy('Cart line field', 'hoarding'))

    date_from = models.DateField(blank=True, null=True,
        verbose_name=pgettext_lazy('Cart line field', 'from'))

    date_until = models.DateField(blank=True, null=True,
        verbose_name=pgettext_lazy('Cart line field', 'until'))

    class Meta:
        unique_together = ('cart', 'date_from', 'date_until')
        verbose_name = pgettext_lazy('Cart line model', 'Cart line')
        verbose_name_plural = pgettext_lazy('Cart line model', 'Cart lines')

当我试图向购物车中添加相同的对象(从日期到日期)时出现错误：

IntegrityError at /hoardings/hoardings-demo-2-5/add/
UNIQUE constraint failed: cart_cartline.cart_id, cart_cartline.date_from, cart_cartline.date_until

当创建具有相同数据的对象时，get_or_create将返回一个IntegrityError，我在datefield中添加了唯一的特性，但得到了相同的错误。我使用Django 1.11和Python2.7

我重置了几次数据库，但没有用，db是Postgres/sqlite。

Answer 1

unique_together在CartLine模型中是导致完整性的issue.Remove这一行，然后迁移。

class CartLine(models.Model):
    cart = models.ForeignKey(
        Cart, related_name='lines',
        verbose_name=pgettext_lazy('Cart line field', 'cart'))

    hoarding = models.ForeignKey(
        Hoarding, related_name='+',blank=True, null=True,
        verbose_name=pgettext_lazy('Cart line field', 'hoarding'))

    date_from = models.DateField(blank=True, null=True,
        verbose_name=pgettext_lazy('Cart line field', 'from'))

    date_until = models.DateField(blank=True, null=True,
        verbose_name=pgettext_lazy('Cart line field', 'until'))

    class Meta:
        verbose_name = pgettext_lazy('Cart line model', 'Cart line')
        verbose_name_plural = pgettext_lazy('Cart line model', 'Cart lines')