流畅的nhibernate，删除不可为空的属性并替换它

发布于 2024-11-06 13:32:03 字数 585 浏览 2 评论 0原文

我有一个具有不可为空属性的对象。

class Notebook {
  Blueprint Blueprint { get; set; }
}

映射

// ...
NotebookMap() {
 // ...
 References(x => x.Blueprint)
  .Not.Nullable()
  .Cascade.All();
}

好的，太棒了。精彩的。

如果我想更改附加到笔记本的蓝图并删除旧蓝图，会发生什么情况？这不起作用..

notebook.Blueprint = // new blueprint code.;

效果很好...但是旧的蓝图不会被删除，它只是愉快地挂在代码中并浪费空间。

如果我尝试这个..

session.Delete(notebook.Blueprint);

我会得到一个错误，因为现在该字段为空（并且它必须是不可为空的）。

有什么办法可以解决这个问题吗？

原文

I have an object with a non-nullable property.

class Notebook {
  Blueprint Blueprint { get; set; }
}

Mapping

// ...
NotebookMap() {
 // ...
 References(x => x.Blueprint)
  .Not.Nullable()
  .Cascade.All();
}

Okay, great. Wonderful.

What happens if I want to change the Blueprint attached to a notebook, and delete the old blueprint? This doesn't work..

notebook.Blueprint = // new blueprint code.;

That works fine... but then the old blueprint isn't deleted, it just hangs around in code happily and wastes space.

If I try this ..

session.Delete(notebook.Blueprint);

I get an error, because now the field is null (and it has to be non-nullable).

Is there any way around this problem?

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岁月如刀 2024-11-13 13:32:03

像这样的事情怎么样？

var oldBlueprint = notebook.Blueprint;
notebook.Blueprint = // new blueprint code;
session.Flush(); // might or might not be needed
session.Delete(oldBlueprint);

当然，该蓝图可能被其他笔记本引用，所以删除仍然可能失败。

How about something like this?

var oldBlueprint = notebook.Blueprint;
notebook.Blueprint = // new blueprint code;
session.Flush(); // might or might not be needed
session.Delete(oldBlueprint);

Of course, the blueprint may be referenced by another notebook, so the delete may still fail.

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