Populating foreign key

J2R · **Joined:** Sun Nov 07, 2004 3:39 pm **Posts:** 77

I have an Organisation class, which contains a List of OrganisationAddress objects. I am finding that when I try to save an address by adding it to the list and saving the parent object as in the code below, unless I have the oa.setOrganisation line the address objects get saved without the foreign keys linking them to the organisation table. I understood that I should not need to explicitly set the parent object, it should get populated automatically by Hibernate.

o=new Organisation();
o.setName("Hibernate World Enterprises");
OrganisationAddress oa=new OrganisationAddress();
oa.setBuilding("51 Rose Valley");
//Do I need this folliwng line?
oa.setOrganisation(o);
o.getAddresses().add(a);
service.storeOrganisation(o);

Rather than clutter up the message with my mapping files, I thought I'd just ask what element it is that I'm likely to be missing here. What does one need to do in a simple one to many mapping like this to ensure that the children get foreign keys populated when saving the parent object?

fraggle · **Posted:** Thu Nov 18, 2004 12:26 pm

What is in your mapping-file?

J2R · **Joined:** Sun Nov 07, 2004 3:39 pm **Posts:** 77

The parent:

<hibernate-mapping>
<class
name="testing.om.organisation.Organisation"
table="organisation"
dynamic-update="false"
dynamic-insert="false"
>

<id
name="id"
column="id"
type="java.lang.Long"
>
<generator class="native">
</generator>
</id>

<property
name="name"
type="string"
update="true"
insert="true"
access="property"
column="name"
length="80"
/>

<property
name="acronym"
type="string"
update="true"
insert="true"
access="property"
column="acronym"
length="20"
/>

<many-to-one
name="organisationType"
class="testing.om.organisation.OrganisationType"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
column="organisation_type_id"
/>

<property
name="URL"
type="string"
update="true"
insert="true"
access="property"
column="url"
length="100"
/>

<property
name="telephoneNo"
type="string"
update="true"
insert="true"
access="property"
column="telephone_no"
length="40"
/>

<property
name="fax"
type="string"
update="true"
insert="true"
access="property"
column="fax"
length="40"
/>

<property
name="email"
type="string"
update="true"
insert="true"
access="property"
column="email"
length="40"
/>

<bag
name="addresses"
lazy="false"
inverse="true"
cascade="all"
>

<key
column="organisation_id"
>
</key>

<one-to-many
class="testing.om.organisation.OrganisationAddress"
/>
</bag>



</class>

</hibernate-mapping>

The child:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class
name="testing.om.Address"
table="address"
dynamic-update="false"
dynamic-insert="false"
>

<id
name="id"
column="id"
type="java.lang.Long"
>
<generator class="native">
</generator>
</id>

<property
name="building"
type="string"
update="true"
insert="true"
access="property"
column="building"
length="80"
/>

<property
name="county"
type="string"
update="true"
insert="true"
access="property"
column="county"
length="40"
/>

<property
name="street"
type="string"
update="true"
insert="true"
access="property"
column="street"
length="80"
/>

<property
name="postcode"
type="string"
update="true"
insert="true"
access="property"
column="postcode"
length="20"
/>

<property
name="postalTown"
type="string"
update="true"
insert="true"
access="property"
column="postal_town"
length="80"
/>

<many-to-one
name="country"
class="testing.om.Country"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
column="country_id"
/>



<joined-subclass
name="testing.om.organisation.OrganisationAddress"
table="organisation_address"
dynamic-update="false"
dynamic-insert="false"
>
<key
column="id"
/>

<many-to-one
name="organisation"
class="testing.om.organisation.Organisation"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
column="organisation_id"
/>

</joined-subclass>

</class>

</hibernate-mapping>

fraggle · **Posted:** Thu Nov 18, 2004 1:18 pm

I would suggest:
Organisation:

Code:

/**
 * @hibernate.class
 */
class Organisation
{
    private Long id;
    private List addresses= new ArrayList();
    /**
      * @hibernate.id generator-class="native"
      */
    public Long getId() 
    {
        return id;
    }
    private void setId(Long id)
    {
        this.id = id;
    }

    /**
      * @hibernate.bag lazy="false" inverse="true" cascade="all-delete-orphan"
      * @hibernate.collection-key column="organisation"
      * @hibernate.collection-one-to-many class="package.Addresses"
      */
    List getAddresses()
    {
        return addresses;
    }
    private void setAddresses(List addresses)
    {
        this.addresses = addresses;
    }
    public void addAddress(Address address)
    {
        address.setOrganisation(this);
        addresses.add(address);
    }
}

Address:

Code:

/**
   * @hibernate.class
   */
class Address
{
    private Long id;
    private Organisation organisation;
    /**
      * @hibernate.id generator-class="native"
      */
    public Long getId() 
    {
        return id;
    }
    private void setId(Long id)
    {
        this.id = id;
    }
    /**
      * @hibernate.many-to-one not-null="true"  
      */
    public Organisation getOrganisation()
    {
         return organisation;
    }
    public void setOrganisation(Organisation organisation)
    {
        this.organisation = organisation;
    }
}

Now You have to save Organisation only once. At this point, you can add Addresses without saving easily:

Code:

Session s = {init session}
Transaction tx = s.beginTransaction();
Organisation o = new  Organisation();
s.save(o);

//are saved automatically
Address a1 = new  Address();
o.addAddress(a1);

Address a2 = new  Address();
o.addAddress(a2);

tx.commit();
s.close();

If You need the Mapping file ... just ask... Think, You are using xcdoclet;)

fraggle · **Posted:** Thu Nov 18, 2004 1:22 pm

When you need to add more elements at a later time You can use this code:

Code:

public void addAddress(Organisation o, Address address)
{
Session s = {init session}
Transaction tx = s.beginTransaction(); 

//reload Organisation (make transient object persistent
o = (Organisation)s.load(Organisation.class, o.getId(), LockMode.NONE);
o.addAddress(address);

tx.commit();
s.close(); 
}

J2R · **Joined:** Sun Nov 07, 2004 3:39 pm **Posts:** 77

Thanks. I'm now getting the following error at the point of saving the parent object. Any ideas why?

SEVERE: Could not synchronize database state with session
net.sf.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: sailingnetworks.om.organisation.OrganisationAddress

fraggle · **Posted:** Thu Nov 18, 2004 1:44 pm

Show me the creating code...

J2R · **Joined:** Sun Nov 07, 2004 3:39 pm **Posts:** 77

The test code (which fails) I posted at the start. The actual DAO code which stores an organisation is the standard Spring saveorUpdate (the DAO class subclasses HibernateDaoSupport - I don't know whether you are familiar with Spring).

public void storeOrganisation(Organisation organisation) throws DataAccessException {
getHibernateTemplate().saveOrUpdate(organisation);
}

fraggle · **Posted:** Thu Nov 18, 2004 1:57 pm

I am not familiar with Spring. But i see, that you get an Organisation object from outside of a session. Is Organisation allready persistent? If so, it is detached and You have to reload it with Session.get or session.load.
So: helps this before you save?

Code:

Organisation o = session.load(Organisation.class, o.getId(), LockMode.NONE);
o.addAddress(address);

or this?

Code:

session.save(o);
o.addAddress(address);

christian · **Posted:** Thu Nov 18, 2004 1:59 pm

Sorry, but this is incorrect. You don't have to load() or refresh() a detached object, you reattach it. The methods are saveOrUpdate(), saveOrUpdateCopy(), or lock() if the detached object hasn't been modified.

fraggle · **Posted:** Thu Nov 18, 2004 2:07 pm

That is true. I was primary interested in a clean persistent object;)
"object references an unsaved transient instance" tells me, the Object is not persistent.

christian · **Posted:** Thu Nov 18, 2004 2:09 pm

It means it is not in a persistent state. This doesn't mean it has to be loaded from the database.

J2R · **Joined:** Sun Nov 07, 2004 3:39 pm **Posts:** 77

I'm not sure what an "unsaved transient instance" is. I'd like to be able to address this problem but don't know where to look.

fraggle · **Posted:** Thu Nov 18, 2004 2:13 pm

...and I would never use saveOrUpdate for performance and "error prone" reasons.

christian · **Posted:** Thu Nov 18, 2004 2:20 pm

Wrong. Please stop giving wrong advice.