django模型保存错误'对象没有属性“field_id”

Question

我有一个带有 2 个可选字段的简单 django 模型。当我尝试保存模型时出现错误。

class Cart(models.Model):
    shipping = models.ForeignKey(ShippingRate, blank=True, null=True)
    date_created = models.DateTimeField(blank=True, null=True)

    def save(self, *args, **kwargs):
        if not self.date_created:
            self.date_created = datetime.datetime.now()
        super(Cart, self).save(*args, **kwargs)

使用简单视图保存购物车对象，我收到以下错误 -

'Cart' object has no attribute 'shipping_id'

调用super() 失败了。我查看了数据库，我的表上有 'id'、'date_created' 和 'shipping_id' 字段。

我正在使用南管理我的数据库，并且我尝试过删除、迁移和替换字段，但这不起作用。这是一个奇怪的 - 我想我错过了一些明显的东西，但我还没有发现它..

更新

我尝试删除 save() 覆盖，甚至换出字段（然后向南迁移）。我将 shipping 字段换成了新的 shipping_rate 字段 -

class Cart(models.Model):
    shipping_rate = models.ForeignKey(ShippingRate, blank=True, null=True)
    date_created = models.DateTimeField(blank=True, null=True)

这次我在保存时遇到同样的错误，只是它是导致它的 date_created 字段。

'Cart' object has no attribute 'date_created'

和以前一样，我浏览了我的 (postgres) 数据库，可以看到我期望的 3 个字段 - id、shipping_rate_id 和 date_created。

更新 2

好的，我已将代码缩减为 -

#models
class Cart(models.Model):
    shipping_rate = models.ForeignKey(ShippingRate, blank=True, null=True)
    modified = models.DateTimeField(blank=True, null=True)

    class Meta():
        app_label = 'cart'

#views
def add_to_cart(request):
    if 'cart' in request.session:
        cart = request.session['cart']
    else:
        cart = Cart()
    if not cart.pk:
        cart.save()
    return HttpResponse('ok')

还有我的回溯-

Traceback:
File "/Users/aidan/Environments/bbhq/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  111.                         response = callback(request, *callback_args, **callback_kwargs)
File "/Users/aidan/Code/bbhq/bbhq/cart/views.py" in add_to_cart
  71.             cart.save()
File "/Users/aidan/Environments/bbhq/lib/python2.7/site-packages/django/db/models/base.py" in save
  463.         self.save_base(using=using, force_insert=force_insert, force_update=force_update)
File "/Users/aidan/Environments/bbhq/lib/python2.7/site-packages/django/db/models/base.py" in save_base
  551.                 result = manager._insert([self], fields=fields, return_id=update_pk, using=using, raw=raw)
File "/Users/aidan/Environments/bbhq/lib/python2.7/site-packages/django/db/models/manager.py" in _insert
  203.         return insert_query(self.model, objs, fields, **kwargs)
File "/Users/aidan/Environments/bbhq/lib/python2.7/site-packages/django/db/models/query.py" in insert_query
  1575.     query.insert_values(fields, objs, raw=raw)
File "/Users/aidan/Environments/bbhq/lib/python2.7/site-packages/django/db/models/sql/subqueries.py" in insert_values
  170.                 value = getattr(obj, field.attname)

Exception Type: AttributeError at /cart/add_to_cart
Exception Value: 'Cart' object has no attribute 'shipping_rate_id'

Answer 1

正如评论中提到的，会话中有一个旧实体在添加新字段之前被腌制。