在休眠状态下在一个表中映射多个集合

Question

我有User一Log堂课（我不能改变）：

class User {
    private long id;
    private String name;
    private Set<Log> accessLogs;
    private Set<Log> actionLogs;
}

class Log {
    private String what;
    private Date when;
}

可能的映射如下所示：

<class name="com.example.User" table="users">
    <id name="id" access="field">
        <generator class="native" />
    </id>

    <property name="name" length="256" />

    <set name="accessLogs" table="user_access_logs" cascade="all-delete-orphan" order-by="`when`">
        <key column="user_id" />
        <composite-element class="com.example.Log">
            <property name="what" length="512" />
            <property name="when" column="`when`" />
        </composite-element>
    </set>

    <set name="actionLogs" table="user_action_logs" cascade="all-delete-orphan" order-by="`when`">
        <key column="user_id" />
        <composite-element class="com.example.Log">
            <property name="what" length="512" />
            <property name="when" column="`when`" />
        </composite-element>
    </set>

</class>

这可以正常工作并映射到以下数据库表：

users
+----+------+
| id | name |
+----+------+
|  1 | john |
|  2 | bill |
|  3 | nick |
+----+------+

user_access_logs
+---------+------------+---------------------+
| user_id | what       | when                |
+---------+------------+---------------------+
|       1 | logged in  | 2010-09-21 11:25:03 |
|       1 | logged out | 2010-09-21 11:38:24 |
|       1 | logged in  | 2010-09-22 10:19:39 |
|       2 | logged in  | 2010-09-22 11:03:18 |
|       1 | logged out | 2010-09-22 11:48:16 |
|       2 | logged in  | 2010-09-26 12:45:18 |
+---------+------------+---------------------+

user_action_logs
+---------+---------------+---------------------+
| user_id | what          | when                |
+---------+---------------+---------------------+
|       1 | edit profile  | 2010-09-21 11:28:13 |
|       1 | post comment  | 2010-09-21 11:30:40 |
|       1 | edit profile  | 2010-09-21 11:31:17 |
|       1 | submit link   | 2010-09-22 10:21:02 |
|       2 | submit review | 2010-09-22 11:10:22 |
|       2 | submit link   | 2010-09-22 11:11:39 |
+---------+---------------+---------------------+

我的问题是，在hibernate状态下如何将这两个集合（accessLogs和actionLogs）映射到同一表中，从而为日志生成以下架构：

user_logs
+---------+---------------+---------------------+--------+
| user_id | what          | when                | type   |
+---------+---------------+---------------------+--------+
|       1 | logged in     | 2010-09-21 11:25:03 | access |
|       1 | edit profile  | 2010-09-21 11:28:13 | action |
|       1 | post comment  | 2010-09-21 11:30:40 | action |
|       1 | edit profile  | 2010-09-21 11:31:17 | action |
|       1 | logged out    | 2010-09-21 11:38:24 | access |
|       1 | logged in     | 2010-09-22 10:19:39 | access |
|       1 | submit link   | 2010-09-22 10:21:02 | action |
|       2 | logged in     | 2010-09-22 11:03:18 | access |
|       2 | submit review | 2010-09-22 11:10:22 | action |
|       2 | submit link   | 2010-09-22 11:11:39 | action |
|       1 | logged out    | 2010-09-22 11:48:16 | access |
|       2 | logged in     | 2010-09-26 12:45:18 | access |
+---------+---------------+---------------------+--------+

编辑
：我想保留Java代码并按原样设置语义。我正在寻找诸如鉴别器，公式或hibernateAPI扩展之类的东西，这些东西可以解决此问题而无需接触Java代码。可能有些事情（虚构的hibernate配置如下）：

<set name="accessLogs" table="user_logs" ... formula="type='access'">
    <key column="user_id" />
    <composite-element class="Log">
        ...
    </composite-element>
</set>

<set name="actionLogs" table="user_logs" ... formula="type='action'">
    <key column="user_id" />
    <composite-element class="Log">
        ...
    </composite-element>
</set>

Edit2 ：我还没有完整的解决方案。我确信可以做到这一点，可能是通过扩展一些hibernateAPI来实现的。

Answer 1

正如Maurizio所写，您需要使用where属性来仅检索属于每个集合的行。

要使用附加列 插入 行，您需要在内添加以下元素<set>：

<sql-insert>
  insert into user_logs(user_id, what, [when], type)
  values(?, ?, ?, 'access')
</sql-insert>

从本质上讲，这告诉Hibernate使用该特定SQL而不是生成它。请注意，我必须手动转义该when列。

奖励：向数据库中添加额外的列，请使用以下命令（关闭之后<class>）

<database-object>
  <create>alter table user_logs add type char(6)</create>
  <drop></drop>
</database-object>

有趣的一点：我使用 NHibernate 编写并测试了此代码，但是它是直接移植的，因此它应该完全一样。