Hi,

I have a table with three fields - a primary key, a unique foreign key and another varchar field. I want to use saveOrUpdate() in the corresponding hibernate code. I want to modify the varchar field if the foreign key value already exists. But it is throwing unique constraint violation (org.hibernate.exception.ConstraintViolationException). Can I use saveOrUpdate in such a situation? Otherwise which is the optimal way to do that?

Thanks & Regards
Merin

Hi merinshaji,
could you post your mapping files?

Hi,

This is my mapping file:


<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping default-access="field">
<class name="com.ProcessStatus" table="PROCESS_STATUS">
<id name="id" column="ID"><generator class="native" /></id>
<property name="status" column="STATUS" />
<many-to-one name="processDef" column="PROCESSDEF"
foreign-key="FK_PROCDEF_STATUS" unique="true" />
</class>
</hibernate-mapping>[/quote]

I was thinking, when you call saveOrUpdate and the constraint is thrown, you do it on a new instance?

1. I think you always have a chance to (a) delete the instance, (b) save a new one (two lines o f code, but also two db operations).

2. i believe that if you in one session load the instance you want to save, change the varchar column and than call saveOrUpdate, you wont have problems with FK or UNIQUE violantions (i do it). would you please send a log file with sql concerning the update? it would seem to me like hibernate is issuing an insert instead of an update.

regards, martin

This is the error I am getting:


Unique constraint violation: SYS_CT_732 in statement [insert into PROCESS_STATUS (ID, STATUS, PROCESSDEF) values (null, ?, ?)]

org.hibernate.exception.ConstraintViolationException: could not insert: [com.ProcessStatus]

It is calling insert, not update.

This is my hibernate code:

ProcessStatus processStatus=new ProcessStatus();
processStatus.setStatus("active");
processStatus.setProcessDef(definition);
Transaction transaction=session.beginTransaction();
try {
session.saveOrUpdate(processStatus);
} catch (HibernateException e) {
transaction.rollback();
e.printStackTrace();
}
transaction.commit();


How will I know if I can load the instance I want to save? I can load it only if the record is present in the table, no? I want to do save for new instance and do update for existing instance using saveOrUpdate. I also don't want to delete the existing record and save again.

Thanks & Regards
Merin

you dont want to craete a new instance (it will always insert), but update an existing one. well, if that's the case i think there is something wrong with your model.

if you have many-to-one with unique constraint, it is in fact one-to-one, so each of your processDef is allowed to have exactly one processStatus instance, am i correct?

if so, you can easilly pick the one you want -- there is only one that matches (you may use hql for example and join ProcessStatus and ProcessDefinition). if you really try to model 1:1 with foreing-key and unique (nothing wrong with that), consider making the association bidirectional

the parent part:



the child part:



just note that i have unique=false in child part, you will have unique true. the problem with my mapping is that is use inheritance and book_entry_id column must be enabled to store NULL values (table-per-hierarchy strategy), in case of MSSQL server for example there are forbuidden multiple NULL values in one unique column (at least i do not know how to enable :-)

once you have it bidirectional, no problem to write the code (and a proper update will be issued -- check it) -- you will be able from processDefinition with single property getter load the proper processStatus.

you can do for example:



was this helpfull?

just an note: i would guess that from a ProcessDefinition there can be several running processes of that type (1:n) independently and each of them should have their state (1:1) (ProcessSatus) -- in that case i miss the 1:n relation.

m.