cascade problem

jackdawson · **Joined:** Thu Sep 25, 2003 9:25 am **Posts:** 15

In my system I have users and one attribute for each:

Code:

<class name="A" table="attribute">
<id name="aId" unsaved-value="-1"><generator class="native"/></id>        
<property name="name" type="string" length="20" />      
...
</class>

<class name="User" table="users">
<id name="userId" unsaved-value="-1"><generator class="native"/></id>
<many-to-one name="a" class="A" column="aId" cascade="all-delete-orphan" />
...
</class>

Users <-> A relationship could well be one-to-one, but I'm using many-to-one just because it's easier to handle (the idea of one-to-one in Hibernate is quite confusing because in the version I'm using you cannot use foreign keys as reference and you have to have the same primary key value).

When I save new user (or update an existing one) I only need to handle the User object and cascade="all-delete-orphan" handles inserting a new value. But, for some users I'd like to set A to null (and then delete A from attribute table). If I try:

Code:

user.update(); // i need to update some other property values of user
user.getA().delete();

I get error:
Flush during cascade is dangerous - this might occur if an object was deleted and then re-saved by cascade, which is totally understandable I think.

Then, if I try:

Code:

user.setA(null);

the row in attribute table is not deleted although it's set to null in user table. Shouldn't "all-delete-orphans" to the deleting? Or, how can I set A in users table to null and delete the corresponding row from attribute table?

jackdawson · **Joined:** Thu Sep 25, 2003 9:25 am **Posts:** 15

Ok, seems that all-delete-orphan is not legal here :)

But, that gets me back to the original problem. When I try to delete attribute with user.getA().delete() I get error. How do I delete the attribute row?

emmanuel · **Posted:** Mon Dec 15, 2003 8:15 am

Code:

user.setA(null);
session.flush();
session.delete(a);

jackdawson · **Joined:** Thu Sep 25, 2003 9:25 am **Posts:** 15

epbernard wrote:

Code:

user.setA(null);
session.flush();
session.delete(a);

Thanks. But doesn't that mean that the transaction is committed when the first flush is made? Now, what if deleting A fails? In that case changes to the user object should NOT be persisted.

emmanuel · **Posted:** Mon Dec 15, 2003 8:38 am

Grrr, This is urban legend and FAQ ;-)
http://www.hibernate.org/74.html#A2

jackdawson · **Joined:** Thu Sep 25, 2003 9:25 am **Posts:** 15

Ok, just testing whether you knew that! :) :)

Thanks!!