one-to-one mapping

tirtzab · **Joined:** Wed Aug 10, 2005 6:49 am **Posts:** 10

I'm having a lot of trouble mapping a one-to-one relationship. I tried with a foreign key asscociation and with both table's primary key's matching. Can someone please show me how to do this?
I have 2 tables : QueryGroup and GroupEmailInfo.
I want the QueryGroup class to contain GroupEmailInfo as a member.
When a new queryGroup is saved I want the related GroupEmailInfo to be saved as well with the correct id.

Here are the classes:

Code:

public class Query_Group implements Serializable {


    /** identifier field */
    private Long id;

    /** nullable persistent field */
    private String interval;

    /** nullable persistent field */
    private Timestamp last_run_dte;

    /** nullable persistent field */
    private String group_name;

    /** nullable persistent field */
    private String group_status_cde;

    /** nullable persistent field */
    private net.idt.ReportEngine.dao.GroupEmailInfo groupEmailInfo;
...

and 

public class GroupEmailInfo implements Serializable {

    /** identifier field */
    private Long id;

    /** nullable persistent field */
    private Long group_id; // not necessary - i would only use this for a foreign key asscociation

    /** nullable persistent field */
    private String subject;

    /** nullable persistent field */
    private String body;

    /** nullable persistent field */
    private String from_address;

How would I map this???
Please help!

fedfil · **Posted:** Mon Aug 22, 2005 8:50 am

hello tirtzab

for one-to-one relation, my method is to create a many-to-one relation with attribut unique="true" and cascade="all" which is equivalent to the one-to-one relation.

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tirtzab · **Joined:** Wed Aug 10, 2005 6:49 am **Posts:** 10

Thanks for your reply.
This is my mapping

Code:

<many-to-one name="groupEmailInfo" class="net.idt.ReportEngine.dao.GroupEmailInfo"       unique="true"  cascade="all"/>

The error I'm getting is

SQLException: ORA-00904: "QUERY_GROU0_"."GROUPEMAILINFO": invalid identifier

fedfil · **Posted:** Mon Aug 22, 2005 9:44 am

hmmm...

first, I set the attribut column (like GROUP_MAIL_INFO_ID)
second, can you give me the script to create Database

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tirtzab · **Joined:** Wed Aug 10, 2005 6:49 am **Posts:** 10

Does the many-to-one have to be inside a parent element?
Here is my mapping

Code:

      <class name="net.idt.ReportEngine.dao.Query_Group" table="tre.Query_Group">
                <id name="id" column="query_group_id" type="long">
                   <generator class="sequence">
                     <param name="sequence">tre.QUERY_GROUP_SEQ</param>
                           </generator>

                </id>
                <property name="interval" type="string"/>
                <property name="last_run_dte" type="timestamp"/>
                <property name="group_name" type="string"/>
                <property name="group_status_cde" type="string"/>
                       <many-to-one name="groupEmailInfo" class="net.idt.ReportEngine.dao.GroupEmailInfo" 
                      unique="true"  cascade="all" property-ref="group_id" />
                           
        </class>

        <class name="net.idt.ReportEngine.dao.GroupEmailInfo" table="tre.Group_Email_Info">
               <id name="id" column="Group_Email_Info_Id" >
                          <generator class="increment"/>
                                  
                </id>
                
                <property name="group_id" type="long"/>
                <property name="subject" type="string"/>
                <property name="body" type="string"/>
                <property name="from_address" type="string"/>

                
        </class>

I am getting this error:
SQLException: ORA-00904: "QUERY_GROU0_"."GROUPEMAILINFO": invalid identifier

tirtzab · **Joined:** Wed Aug 10, 2005 6:49 am **Posts:** 10

Am I doing the many-to-one on the wrong side? Should it be defined in the GroupEmailInfo?

fedfil · **Posted:** Tue Aug 23, 2005 3:10 am

I think your error is to set property-ref="group_id".
property-ref is used to have a bi-directionel relation like Query_Group <-> GroupEmailInfo.
You can try this :

Code:

                       <many-to-one name="groupEmailInfo" class="net.idt.ReportEngine.dao.GroupEmailInfo"
                      unique="true"  cascade="all" column="GROUP_ID" /> 

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