one-to-many associations with assigned PK

shehzad · **Joined:** Mon Dec 01, 2003 2:03 pm **Posts:** 6

I am trying to implement a one-to-many association with a assigned String identifier. I have a simple parent child relationship like :

/*** Parent.hbm.xml***/

Code:

<hibernate-mapping>
<class name="org.opcapl.profession.model.Parent" table="parent">
<id column="parent_id" name="id" type="java.lang.String">
<generator class="assigned"/>
</id>

<property column="name" length="255" name="name" type="java.lang.String"/>

<set name="children" inverse="true" cascade="all" lazy="true" >
     <key column="parent_id"/>
     <one-to-many class="org.opcapl.profession.model.Child"/>
</set>

</class>
</hibernate-mapping>

/*** Child.hbm.xml***/

Code:

<hibernate-mapping>
<class name="org.opcapl.profession.model.Child" table="child">
<id column="id" name="id" type="java.lang.Long">
<generator class="identity"/>
</id>
<property column="name" length="255" name="name" type="java.lang.String"/>

<many-to-one name="parent" class="org.opcapl.profession.model.Parent" column="parent_id" not-null="true"/>
</class>
</hibernate-mapping>

This is exactly the implementation from the hibernate doc except that I have changed the primary key type of the parent table to assigned.
this is not working.
I am trying to do like this :

Code:

            Parent parent = new Parent();
            parent.setName("parent");
            parent.setId("XXXXX");
            Child child = new Child();
            child.setName("child");
            parent.setChildren(new HashSet());
            parent.addChild(child);
            session.save(parent);
            session.flush();
            session.connection().commit();
            session.close();

I got the following exception :

Code:

Hibernate: insert into child (name, parent_id) values (?, ?)
17:48,000  WARN JDBCExceptionReporter:38 - SQL Error: 515, SQLState: 23000
17:48,000 ERROR JDBCExceptionReporter:46 - Could not insert NULL value into 'parent_id' column, table 'Dev.dbo.child'. this column does not accpet NULL value. INSERT failed.
17:48,000 ERROR JDBCExceptionReporter:37 - Could not insert

this code is working perfectly with an 'indentity' sequence identifier, why it is not working with assigned?

thanks for your help.
S.Shehzad

gbonnard · **Posted:** Mon Dec 01, 2003 2:54 pm

You should put a parent attribute in your child class

emmanuel · **Posted:** Mon Dec 01, 2003 3:12 pm

Code:

child.setParent(parent);

shehzad · **Joined:** Mon Dec 01, 2003 2:03 pm **Posts:** 6

Hi,

Actually in the method addChild of parent I am setting the parent property to the child;

Code:

parent.addChild(child c) {
  c.setParent(this)
  this.children.add(c);

}

which is the same : child.setParent(parent);

gavin · **Posted:** Mon Dec 01, 2003 7:49 pm

Try not to mix and match "identity" key generation with other id generation strategies. Or, if you must, you might need to handle things a bit more "manually" by turning off cascade and calling flush() at the right time, etc.

Classes with "identity" id generation are inserted immediately, instead of using write-behind.

shehzad · **Joined:** Mon Dec 01, 2003 2:03 pm **Posts:** 6

Hi,
I have turned off the cascade..
the parent is saved but not the child.

thanks for your help.

S.Shehzad

gavin · **Posted:** Tue Dec 02, 2003 6:13 am

obviously, if you turn off cascade, you need to save them both manually....