Django一对多的领域没有反转依赖 [英] Django one-to-many field without reversing dependency

问题描述

有很多地方建议使用 ForeignKey 进行一对多或多对一的关系，但我很难理解这将如何工作没有反转依赖关系。

There are quite a few places to suggest using ForeignKey for one-to-many or many-to-one relationship, but I am struggling to understand how this will work without reversing dependency.

例如：

我有这两个应用程序，结算和付款理想情况下，定居点不需要知道付款，因为支付记录是在结算后创建的，支付记录可以包含多个结算单。

I have these 2 apps, 'settlements' and 'payments', ideally, settlements don't need to know about payments because payment records are created after settlements have been made, and a payment record can contain multiple settlements.

结算模型：

class Settlement(models.Model):
    ...

付款模式：

class Payment(models.Model):
    settlements = models.ManyToManyField('Settlement')
    ....

这带来了一个基本的模式警告，该结算可以属于多个付款，这不应该发生。

This brings a fundamental schema caveat, that settlement can belong to multiple payments, which should not happen.

执行结算不能属于更多一个支付记录，我将不得不在结算中支付 foreignkey ：

To enforce a settlement cannot belong to more than one payment record, I will have to put the payment foreignkey in Settlement:

结算模型：

settlements model:

class Settlement(models.Model):
    payment = models.ForeignKey('Payment')
    ...

付款模式：

class Payment(models.Model):
    ....

While this enforce the schema validity, but seems the dependency has reversed, now that settlement needs to know about payment, just made these 2 apps tightly coupled. Also I need to create a settlement record with payment field being null, create the payment record, then go back to the settlement record to link up the payment record, this seems wrong.

推荐答案

我的同事发现这个项目：

A colleague of mine found this project:

https://github.com/adsworth/django-onetomany

它在manytomany关系。

It's adding a unique together constraint in the manytomany relationship.

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