级联插入一对多与流利的NHibernate [英] Cascade insert on one-to-many with fluent NHibernate

问题描述

我有两个映射使用流利的NHibernate的用户和UserRoleAssignment。用户有许多UserRoleAssignments。下面是用户的相关地图：

  HasMany（x => x.Roles）
 .Table（UserRoleMap ）
 .Cascade.SaveUpdate（）; 
  

而对于UserRoleAssignment：

  Map（x => x.User_Id）; 
  

正如您所看到的，我只是从User到UserRoleAssignment引用。从UserRoleAssignment，我只映射外键列（User_Id）。
问题是，当我保存用户时，由于外键约束导致异常，因为NHibernate在User_id属性的值中插入0。这只发生在新用户 - 现有的用户（已经有一个ID），工作正常。

所以问题是，我怎样才能确保NHibernate设置值User_Id添加到插入新用户时生成的ID？

非常感谢！

解决方案

这在 http：// nhibernate中有记录。 info / doc / nh / en / index.html＃collections-onetomany ：

lockquote

非常重要注意： / em>如果< one-to-many> 关联的< key> code> NOT NULL ，NHibernate在创建或更新关联时可能会导致约束违规。为了避免这个问题，你必须使用一个双向关联来标记 inverse =true。请参阅本章稍后讨论的双向关联。

I have two classes mapped using fluent NHibernate - User and a UserRoleAssignment. An User has many UserRoleAssignments. Here's the relevant map for user:

HasMany(x => x.Roles)
.Table("UserRoleMap")
.Cascade.SaveUpdate();

And for UserRoleAssignment:

Map(x => x.User_Id);

As you can see, I'm only referencing from User to UserRoleAssignment. From UserRoleAssignment, I'm only mapping the foreign key column (User_Id). The problem is, that when I save the user, I get an exception caused by the foreign key constraint, because NHibernate is inserting 0 in the value for the User_id property. This only happens on new users - existing users (which already has an ID), works fine.

So the question is, how can I make sure that NHibernate sets the value of User_Id to the ID generated when inserting the new User?

Thanks a lot!

解决方案

This is documented in http://nhibernate.info/doc/nh/en/index.html#collections-onetomany:

Very Important Note: If the <key> column of a <one-to-many> association is declared NOT NULL, NHibernate may cause constraint violations when it creates or updates the association. To prevent this problem, you must use a bidirectional association with the many valued end (the set or bag) marked as inverse="true". See the discussion of bidirectional associations later in this chapter.

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