Question

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.

Answer 1

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>