Parent needs to be saved before child

jc_egea · **Joined:** Tue Dec 19, 2006 12:55 pm **Posts:** 27

Hi,

I have the following problem. We have two entities A and B, B have a FK to A (B -> A), so A is the parent in this relationship. In my hbms for A and B I have this:

A.hbm.xml

Code:

<set name="bSet" inverse="true" lazy="true" table="B_TABLE"  cascade="all">
 <key column="bColumn" />
 <one-to-many class="foo.B" />
</set>   

B.hbm.xml

Code:

<many-to-one name="aEntity" column="aColumn" class="foo.A" 
  not-null="true" cascade="none" />   

If i try the next pseudocode, it returns an exception saying (null or transient etc, i haven't the trace here):

Code:

// Code for starting transaction

A aObj= new A();
B bObj= new B();

bObj.setAEntity(aObj);
aObj.setBSet(new HashSet<B>());
aObj.getBSet().add(bObj);

session.saveOrUpdate(aObj);
session.flush();

// Code for finishing transaction

Any help would be appreciated, we are using hibernate 3.0.5

Thanks in advance.

jc_egea · **Joined:** Tue Dec 19, 2006 12:55 pm **Posts:** 27

I forgot it, the last code throws an exception, so I have to save first the parent and after that i'm able to save the child ....

nordborg · **Posted:** Mon Feb 16, 2009 2:37 pm

There is an error in the <set> mapping in A.hbm.xml

Code:

shold be:

Code:

jc_egea · **Joined:** Tue Dec 19, 2006 12:55 pm **Posts:** 27

Hi, you are right, i posted A.hbm.xml with an error, but i have it correct in my real application. What i need to know is if the following code is ok and if it should work. Nowadays it throws an exception about transient, null ... and mentions A object ...

Code:

// Code for starting transaction 

A aObj= new A(); 
B bObj= new B(); 

bObj.setAEntity(aObj); 
aObj.setBSet(new HashSet<B>()); 
aObj.getBSet().add(bObj); 

session.saveOrUpdate(aObj); 
session.flush(); 

// Code for finishing transaction

Thanks in advance

nordborg · **Posted:** Tue Feb 17, 2009 6:04 am

The code seems to be ok, and also the <set> and <many-to-one> mapping. It would be useful to see the complete stacktrace, and maybe also a debug log from Hibernate.

jc_egea · **Joined:** Tue Dec 19, 2006 12:55 pm **Posts:** 27

Here is the exception returned, there's no more trace:

Code:

org.springframework.orm.hibernate3.HibernateSystemException: not-null property references a null or transient value: foo.B.aEntity; nested exception is org.hibernate.PropertyValueException: not-null property references a null or transient value: foo.B.aEntity

Thanks a lot.

jc_egea · **Joined:** Tue Dec 19, 2006 12:55 pm **Posts:** 27

Hi, i forgot an important detail in my code, there's a merge ... and it's the merge method who throws the exception (i've already checked this). Can't i invoke the merge for new data to be inserted?

Code:

// Code for starting transaction 

A aObj= new A(); 
B bObj= new B(); 

bObj.setAEntity(aObj); 
aObj.setBSet(new HashSet<B>()); 
aObj.getBSet().add(bObj); 

session.saveOrUpdate(session.merge(aObj)); 
session.flush(); 

// Code for finishing transaction 

Greets

mmerder · **Posted:** Tue Feb 17, 2009 7:41 am

No, merge is used to reattach detached objects. Your objects are transient, it is enough to call saveOrUpdate.

jc_egea · **Joined:** Tue Dec 19, 2006 12:55 pm **Posts:** 27

Before you tell me... i know the merge is not necessary there, but i use it because is code inside a more generic method ...

Thanks

jc_egea · **Joined:** Tue Dec 19, 2006 12:55 pm **Posts:** 27

Ok, thanks for your replies, it's clear now, greets.