问题描述
这是交易：
我有两个数据库模型，让我们说 ShoppingCart 和顺序。遵循DRY原则，我想将一些常见的道具/方法提取到共享界面 ItemContainer 。
I got two db models, let's say ShoppingCart and Order. Following the DRY principle I'd like to extract some common props/methods into a shared interface ItemContainer.
一切很好，直到我遇到了主要对相关对象集执行删除的 _flush（）方法。
Everything went fine till I came across the _flush() method which mainly performs a delete on a related object set.
class Order(models.Model, interface.ItemContainer):
# ...
def _flush(self):
# ...
self.orderitem_set.all().delete()
所以问题是：我如何动态地知道它是 orderitem_set 或 shoppingcartitem_set ？
So the question is: how do I dynamically know wheter it is orderitem_set or shoppingcartitem_set?
推荐答案
首先，这里有两个Django片段，应该是你正在寻找的：
First, here are two Django snippets that should be exactly what you're looking for:
- Model inheritance with content type and inheritance-aware manager
- ParentModel and ChildManager for Model Inheritance
其次，您可能需要重新考虑设计并切换到django.contrib ，其中有一个简单的方法。 （上面发布的第一个片段也使用内容类型框架）。
Second, you might want to re-think your design and switch to the django.contrib content types framework which has a simple .model_class() method. (The first snippet posted above also uses the content type framework).
第三，你可能不想在你的模型类。这不应该是必要的，如果有一些模糊的副作用，我不会感到惊讶。只需 interface.ItemContainer 继承自 models.Model 然后订单只继承 interface.ItemContainer 。
Third, you probably don't want to use multiple inheritance in your model class. It shouldn't be needed and I wouldn't be surprised if there were some obscure side affects. Just have interface.ItemContainer inherit from models.Model and then Order inherit from only interface.ItemContainer.
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