实体框架中的WillCascadeOnDelete如何工作？ [英] How does WillCascadeOnDelete in Entity Framework work?

问题描述

据我了解，如果删除父行，并且在删除时启用层叠，则应删除其子行。但是，从我的测试来看，它似乎根本不起作用。不管我将WillCascaseOnDelete设置为true还是false，它都只是将其子级的外键设置为null。这导致另一个问题，我必须将外键设置为可空，否则，SaveChange将引发异常。这是缺陷还是期望的行为？

As I understand, if I delete a parent row, its children should be deleted if I turn on cascade on delete. However, from my testing, it doesn't seem to work at all. No matter if I set WillCascaseOnDelete to true or false, it simply sets the foreign key of its children to null. This is causing another problem that I have to set the foreign key nullable, otherwise, SaveChange will throw exception. Is this a defect or desired behavior?

推荐答案

这是因为您的外键（子代）可以为空。默认情况下，删除父级时，如果关系上的外键可为空，则EF会删除父级并将外键设置为null。如果外键不是NOT NULL，它将删除子项（您正在寻找的行为？）。

This is because your foreign keys (child) are nullable. By default, when deleting parent, if the foreign key on the relationship is nullable EF will delete the parent and set the foreign key to null. If the foreign key is NOT NULL it will delete the child (the behaviour you're looking for?).

您可以更改此默认行为此处

You can alter this default behaviour here

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