尝试从其他模型中提取值时出现Django ManyToManyField错误

debugcn 发表于 Dev

卡纳吉

我正在尝试使用纯django重新创建Groupon，并且在以下方面遇到了麻烦。这是我的主意

商家可以发起一个Campaign（具有唯一的CampaignID）
客户（拥有自己的唯一ID）可以保存广告系列，以便以后兑换

我创建了一个包含3列的模型（CampaignID，CustomerID和默认值为False的布尔值字段）

class Customer_save(models.Model):

    Customer_ID = models.ManyToManyField(Customer)
    Campaign_ID = models.ManyToManyField(Campaigns)
    Redeemed = models.BooleanField(default = False) #False denotes that it hasnt been redeemed yet

    def __str__(self):
        return self.Customer_ID.username,self.Campaign_ID.Campaign_desc

我正在尝试创建一个伪造的行，以测试是否所有内容都正确地放入表中。但是我遇到了错误。你能告诉我我要去哪里了吗？

Campaign_ID = '10001'
Customer_ID = 'C12345'

    Customer_save.add(Customer_ID = Customer_ID,Campaign_ID = Campaign_ID)
    Traceback (most recent call last):
      File "<console>", line 1, in <module>
    AttributeError: type object 'Customer_wallet' has no attribute 'add'

>>> New = Customer_save(Customer_ID = Customer_ID, Campaign_ID `=Campaign_ID)`
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/kj/Desktop/projects/lib/python3.4/site-packages/django/db/models/base.py", line 480, in __init__
    raise TypeError("'%s' is an invalid keyword argument for this function" % list(kwargs)[0])

>>> new = Customer_save.Customer_ID.create(Customer_ID = Customer_ID)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
AttributeError: 'ReverseManyRelatedObjectsDescriptor' object has no attribute 'create'
TypeError: 'Customer_ID' is an invalid keyword argument for this function

您需要先创建相关记录，然后再将它们分配给多对多字段：

customer = Customer(...)
customer.save()
campaign = Campaigns(...)
campaign.save()
customer_save = Customer_save(Redeemed=...)
customer_save.save()
customer_save.Customer_ID.add(customer)
customer_save.Campaign_ID.add(campaign)

有关Django文档的更多信息：多对多关系。

PS。我建议您为您的字段和模型选择更好的名称，并遵循正式的样式指南。它们有点误导，并且通常这样的名称会引起混乱，不必担心其他人很难遵循您的代码。

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