我有User
个Log
课程(我无法更改):
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>
这样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 |
+---------+---------------+---------------------+
我的问题是如何在hibernate中将这两组(accessLogs
和actionLogs
)映射到同一个表中,为日志生成以下模式:
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代码和Set语义。我正在寻找像鉴别器,公式或hibernate API扩展这样的东西来解决这个问题而不涉及Java代码。也许就行了(假想的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。我确信可以通过扩展一些hibernate API来完成它。
答案 0 :(得分:11)
您是否尝试以这种方式映射集:
<set name="accessLogs" table="user_logs" where="type='access'">
答案 1 :(得分:5)
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<set>
中添加以下元素:
<sql-insert>
insert into user_logs(user_id, what, [when], type)
values(?, ?, ?, 'access')
</sql-insert>
这实质上告诉Hibernate使用特定的SQL而不是生成它。请注意,我必须手动转义when
列。
奖励:要将额外的列添加到数据库,请使用以下内容(在关闭<class>
之后)
<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 编写并测试了它,但它是直接移植的,所以它应该完全相同。
答案 2 :(得分:1)
为什么不将列表合并到一个列表中呢?您的两个列表都属于同一类。
编辑 - 如果你想保留2个列表,那么创建一个组合的第三个列表,并且只保留它。您将必须控制对两个列表的访问者的访问权限,因此您知道何时更新第三个列表,但不应该太难。