在现有数据库上休眠一对多单向 [英] Hibernate One-To-Many Unidirectional on an existing DB

问题描述

你好堆栈溢出专家，我需要你的专家：

我想在现有的数据库上使用Hibernate。
目前我试图加载一个User对象和一个UserData对象列表。

在DB中，（简化）布局是

  |用户| | UserData | 
 ---------------- ------------------------------ ----- 
 uid |用户名| | uid | parentuid |字段|值| 
  

因此，每个User对象都与UserData.parentuid = User.uid。

我的用户类映射文件

 < class name =com.agetor .commons.security.Usertable =ac_users> 
< id name =uidcolumn =uidtype =long> 
<！ - < generator class =native/>  - > 
< / id> 
< property name =usernamecolumn =username/> 
 
< list name =fieldDatacascade =all> 
< key column =parentuidnot-null =true/> 
< index column =parentuid/> 
 < / list> 
 
< / class> 
  

 < class name =com.agetor.commons.fields.FieldDatatable =ac_userdef_data> 
< id name =uidcolumn =uidtype =long> 
<！ - < generator class =native/> - > 
< / id> 
<！ - < property name =parentuidcolumn =parentuid/> - > 
< property name =fieldnamecolumn =fieldname/> 
< property name =valuecolumn =value/> 
< / class> 
  

到目前为止，我已经尝试了许多不同的配置，并且它们都具有不同程度的失败。代码粘贴在这里，不起作用。

• parentuid属性被注释掉了，因为Hibernate在映射中给出了重复列错误。


• 目前，在uid字段中仍然存在映射中的重复列，我使用< list-index />


• 我不明白我在哪里指定UserData.parentuid是外键，并且列表应该使用User.uid作为键。
  

我希望有人能够提供帮助。

---

当您定义一对多和一个多对一，这是不是让它双向？
当前的工作模型是Unidirectional，UserData没有对用户的引用。您的建议失败，因为Hibernate无法为UserData上的User找到get或set方法。

是否暗示此代码使用User.uid作为键并匹配这对于UserData.parentuid列？或者是这个事实指定在别的地方？

 < list name =fieldDatainverse =true> 
< key column =parentuidnot-null =true/> 
 < / list> 
  

我仍在学习Hibernate，并通过我可以找到的文档和示例工作。

解决方案

这是这个问题的最新进展。该配置可以成功从数据库加载。保存不起作用。
我决定改变数据库的设计，所以我在这里发布这里供其他人参考，在我放弃这种方法之前。

 < class name =com.agetor.commons.security.Usertable =ac_users> 
< id name =uidcolumn =uidtype =long> 
< generator class =increment/> 
< / id> 
< property name =deletedcolumn =deleted/> 
< property name =usernamecolumn =username/> 
< property name =passwordcolumn =passwd/> 
< property name =disabledcolumn =disabled/> 
< property name =lockoutcolumn =lockout/> 
< property name =expirescolumn =expires/> 
< bag name =fieldDatalazy =extra> 
< key column =parentuidnot-null =true/> 
 < / bag> 
< bag name =groupstable =ac_group_relaccess =fieldlazy =extra> 
< key column =useruid/> 
 < / bag> 
< join table =ac_userdef_dataoptional =truefetch =join> 
< subselect> 
从
中选择
 * 
 ac_userdef_data data 
其中
 data.objectname ='user'和
 data.fieldname ='firstname'
< / subselect> 
< key column =parentuid/> 
 < / join> 
< join table =ac_userdef_dataoptional =truefetch =join> 
< subselect> 
从
中选择
 * 
 ac_userdef_data数据
其中
 data.objectname ='user'和
 data.fieldname ='lastname'
< / subselect> 
< key column =parentuid/> 
 < / join> 
 
< / class> 
  

Hello Stack Overflow Experts, i have need of your expertice:

I am trying to use Hibernate on an Existing DB. Currently im trying to load a User object and a list of UserData objects that go along.

in the DB the (simplified) layout is

|    User      |      |          UserData               |
----------------      -----------------------------------
uid | username |      | uid | parentuid | field | value | 

So each User object matches all the UserData objects where UserData.parentuid = User.uid.

My User class mapping file

    <class name="com.agetor.commons.security.User" table="ac_users">
    <id name="uid" column="uid" type="long" >
        <!--<generator class="native"/>-->
    </id>
    <property name="username" column="username" />   

    <list name="fieldData" cascade="all">
        <key column="parentuid" not-null="true" />
        <index column="parentuid" />
        <one-to-many class="com.agetor.commons.fields.FieldData"/>
    </list>

</class> 

Mu UserData mapping file

    <class name="com.agetor.commons.fields.FieldData" table="ac_userdef_data">
    <id name="uid" column="uid" type="long" >
    <!--<generator class="native"/> -->
    </id>
    <!--<property name="parentuid" column="parentuid" />   -->
    <property name="fieldname" column="fieldname" />
    <property name="value" column="value" />
</class>

So far i have tried many different configurations and all of them have had various degrees of failue. The code pasted here, does not work.

• The parentuid property is commented out, because Hibernate gives a "Repeated column in mapping" error otherwise.
• Currently there is still a "Repeated column in mapping" on the uid field, i use for <list-index />
• I do not understand where i specify that UserData.parentuid is the foreign key and that the list should use User.uid as key.

I hope someone is able to help.

---

When you define both a One-To-Many and a Many-To-One, does this not make it Bi-Directional? The current working model, is Unidirectional and UserData does not have a reference to User. Your suggestion fails, because Hibernate could not find a get or set method for User on UserData.

Is it implied that, this code uses User.uid as a key and matches this against the UserData.parentuid column? Or is this fact specified somewhere else?

  <list name="fieldData" inverse="true">
    <key column="parentuid" not-null="true" />
    <one-to-many class="com.agetor.commons.fields.FieldData"/>
  </list>

I am still learning Hibernate and working my way through documentation and examples i can find.

解决方案

This is the latest development on this problem. This configuration can succesfully load from the Database. Saving does not work. I have decided to alter the Database design instead, so im posting this here for reference for others, before i abandon this approach.

    <class name="com.agetor.commons.security.User" table="ac_users">
    <id name="uid" column="uid" type="long" >
        <generator class="increment"/>
    </id>
    <property name="deleted" column="deleted" />
    <property name="username" column="username" />   
    <property name="password" column="passwd" />
    <property name="disabled" column="disabled" />
    <property name="lockout" column="lockout" />
    <property name="expires" column="expires" />
    <bag name="fieldData" lazy="extra">
        <key column="parentuid" not-null="true" />
        <one-to-many class="com.agetor.commons.fields.FieldData"/>
    </bag>
    <bag name="groups" table="ac_group_rel" access="field" lazy="extra">
        <key column="useruid"/>         
        <many-to-many column="groupuid" class="com.agetor.commons.security.Group"/>
    </bag>         
    <join table="ac_userdef_data" optional="true" fetch="join">
        <subselect>
            select
                *
            from
                ac_userdef_data data
            where
                data.objectname = 'user' and
                data.fieldname = 'firstname'
        </subselect>
        <key column="parentuid" />
        <property name="firstname" formula="(select data.value from ac_userdef_data data where data.fieldname = 'firstname' and data.uid = uid)"/>
    </join>
    <join table="ac_userdef_data" optional="true" fetch="join">
        <subselect>
            select
                *
            from
                ac_userdef_data data
            where
                data.objectname = 'user' and
                data.fieldname = 'lastname'
        </subselect>        
        <key column="parentuid" />
        <property name="lastname" formula="(select data.value from ac_userdef_data data where data.fieldname = 'lastname' and data.uid = uid)"/>
    </join>

</class>

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