I have a one to many relationship in my DB. The User table has a one to many relationship with User_Roles table. The User_Roles table has the user_id as a foreign key and the int column to identify the actual user role.

On the java side the Role object is implemented as Hibernate PersistentEnum, with a standard enum implementation. The User object has a collection of Role objects (PersistentEnum's). The problem comes when I want to map this collection. I am trying to map it as a one-to-many collection. Below is the mapping doc extract.

<bag name="roles" table="user_roles">
<key column="USER_ID_FK"/>
<one-to-many class="com.matchboxsoftware.tickettout.domain.Role"/>
</bag>

The immediate obvious problem is that my PersistentEnum does not have a zero argument constructor....the nature of enums. My question is, is it possible to even persist my enum in a one to many type relationship? If so how would I do it? Or should I simply implement the Role object as a standard class (not what I really want to do)?

Any help would be greatly appreciated.

Thanks

This is how you do it:

I tried the aforementioned solution but it's still not working. I am still getting an "Object Role must declare a default (no argument) constructor" exception from Hibernate.

Here is the pretty standard PersistentEnum class.



Here is the mapping doc.

<bag name="roles" table="user_roles" inverse="false" cascade="delete" >
<key column="USER_ID_FK"/>
<element type="com.matchboxsoftware.tickettout.domain.Role" column="ROLE_ENUM_ID"/>
</bag>

Hello,

Did anyone ever find a solution to this? I'm running into the same problem. I also wonder if I'm solving the problem the right way.

Any hints would be greatly appreciated!

Thanks,
Seth

Well, I never actually believed this one..... do you have a stack trace?

Try adding



to your Role class?

Hi Gavin,

I'm in the middle of trying this right now. Sorry for the confusion from my previous post. I should have said "I'm trying this as well" instead of "I'm having the same problem".

I was led down the wrong path a bit by trying to get xdoclet to handle this. Apparently, xdoclet will only map a class to a one-to-many. For this example to work, we need an element.

I'm using xdoclet's merge capabilities to place this into my mapping file:

<set
name="activities"
table="BUSINESS_ACTIVITIES"
lazy="true"
inverse="false"
cascade="delete"
sort="unsorted"
>

<key
column="business_id"
/>

<element
column="activity_id"
type="com.hic.eboss.Activity"
/>
</set>

A good sign is that the SchemaGenerator seemed to do the right thing and created a BUSINESS_ACTIVITIES table.

I'll post a followup when I get the test running.

Thanks again,
Seth

Seems like it works great! Now if I can get xdoclet to manage this relationship for me.... :)

Thanks for your always prompt help. Good luck with the book!

public void testDB() throws Exception {
Session session = SessionManager.getSession();
Transaction txn = SessionManager.getTransaction();
biz.setName("foo");
biz.addActivity(Activity.COMMISSIONS);
biz.setType(BizType.SOLE_PROPRIETORSHIP);
session.save(biz);
session.flush();
txn.commit();
SessionManager.closeSession();

String id = biz.getId();

session = SessionManager.getSession();
biz = (Business) session.load(Business.class, id);

assertTrue(biz.getActivities().contains(Activity.COMMISSIONS));

SessionManager.closeSession();
}

Can't you do it with:

/**
* @hibernate.collection-element column="something" type="PersistentEnum"
* @hibernate.set
*/

Or something like that?

Thanks! That worked great. I didn't realize I could replace collection-one-to-many with collection-element.

I really appreciate it. Thanks again.

Seth