python - 使用未保存的相关对象保存对象

Question

django 没有提供自动保存未保存的相关对象的功能吗？

来自docs :

Changed in Django 1.8.4:

Previously, saving an object with unsaved related objects did not raise an error and could result in silent data loss. In 1.8-1.8.3, unsaved model instances couldn’t be assigned to related fields, but this restriction was removed to allow easier usage of in-memory models.

我能理解为什么会有

ValueError: save() prohibited to prevent data loss due to unsaved related object

而不是默认保存该对象(我的猜测是显式优于隐式)，但我什至无法找到上述功能请求。

Answer 1

来自ticket that lead to the change

I prefer failing early and loudly, by raising an exception when an unsaved object is assigned to a related field.

I could listen to an argument for trying to re-fetch the pk from the cached related instance in save(), but that feels like action-at-a-distance: the actual problem usually happened earlier.

Automatically saving related objects is too magic; I'm sure it would be considered unexpected and undesirable in some circumstances.

我的解释是，Django 的开发者不希望人们养成自动保存东西的习惯，因为这只会导致在不同的时间点出现问题。每个对象的显式保存可确保开发人员充分了解保存的内容，并减少对一行代码中断功能的意外更改。