[Hibernate-issues] [Hibernate-JIRA] Closed: (HB-336) composite id index generation in one-to-many association

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Message:

   The following issue has been closed.

   Resolver: Gavin King
       Date: Tue, 16 Sep 2003 8:52 PM

This is expected functionality. There have been many discussions about why this is virtually impossible to do "better", given Hibernate's support for detached objects.
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View the issue:

  http://opensource.atlassian.com/projects/hibernate/secure/ViewIssue.jspa?key=HB-336


Here is an overview of the issue:
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        Key: HB-336
    Summary: composite id index generation in one-to-many association
       Type: Bug

     Status: Closed
   Priority: Major
 Resolution: REJECTED

    Project: Hibernate2
   Versions:
             2.1 beta 3

   Assignee: 
   Reporter: Antonio martos

    Created: Tue, 16 Sep 2003 3:48 AM
    Updated: Tue, 16 Sep 2003 8:52 PM
Environment: Hibernate 2.1 beta 3b, J2SDK 1.4.1, Oracle 9.2.0.1

Description:

I have 2 persistent classes (Parent.class and Child.class), that are associated by a one to many relationship. The child 
class has a composite id as its Primary Key. This composite id has 2 fields: the first one is Foreign Key of a field from the 
Parent and the second one is an index field. I create a collection child data (list) and add it to the parent, and try to 
persist all (save). The problem is that my index is NOT automatically generated, and so I have to specify it manually each 
time I add a child. I suspect that the problem is that my index is also part of the primary key of the child class, because 
when I've worked with other relations with index columns that are not primary key (or part of) of the corresponding tables, 
hibernate generates the index automatically following the order given in the Collection.
If you don't specify the value of the index, you'll see that hibernate tells you that you can't give a null value to that 
field (just like if it wasn't generated)
This is the implementation of the one to many relationship between both classes (mapped to two tables). The Parent one has a 
Primary Key composed of one field of type integer, just like this: 
<hibernate-mapping>
    <class
        name="es.Parent"
        table="PARENT"
        dynamic-update="false"
        dynamic-insert="false"
    >
        <id
            name="reportId"
            column="REPORT_ID"
            type="java.lang.Integer"
        >
            <generator class="assigned">
            </generator>
        </id>
 ....
    </class>
</hibernate-mapping>
In the Parent xml mapping file, this is the implementation used specifying the relation:
        <list
            name="children"
            lazy="false"
            inverse="true"
            cascade="all"
        >
              <key
                  column="REPORT_ID"
              />
              <index
                  column="SEQ_NUMBER"
              />
              <one-to-many
                  class="es.Child"
              />
        </list>

The Child class has a composite-id composed by a Foreign key (Primary Key of the Parent class) and a sequence number (index 
of the relationship):
<hibernate-mapping>
    <class
        name="es.Child"
        table="CHILDREN"
        dynamic-update="false"
        dynamic-insert="false"
    >
        <composite-id
            name="children_id"
            class="es.ChildId"
            unsaved-value="any"
        >
                     <key-property
                        name="sequenceNumber"
                        type="java.lang.Integer"
                        column="SEQ_NUMBER"
                />
                    <key-many-to-one
                        name="report"
                        class="es.Parent"
                        column="REPORT_ID"
                    />
        </composite-id>
 ... child properties ....
    </class>
</hibernate-mapping>
I've looked for an answer in faqs and in the document reference and I've found nothing related to this issue.

Thank you.



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