All my tables have a column 'status' which can be set to DELETED - since a cannot for some purposes erase the entries from the db.

My approach is when i read objects with hibernate from the database i always specify a where "status!=deleted" clause. this works fine specialy for collections which are read from association-tables e.g. User has n Groups.
User.getGroups() only retrieves the Groups from the table user2group (userId,groupId,status) with status != DELTED.
To set the status to DELETE i have a class UserGroupRelation which just reperesents a sinlge row a the mentioned table.

The problem which now arises when i try to remove a group from a user.



How can i prevent the phy.delete??
Or is the approach kind of uncommon, stupid??
Is there a best-practice-method to the whole "delete by flag" problem?

Thanks in advance
Jens Zastrow

mcbain,

as per my understanding, you have a table called user2group (userId,groupId,status). The table is mapped with the UserGroupRelation class.

Now if you set the "status" to DELETED for any row, it means you have done a soft delete on it. Now while fetching as you are checking "status!=deleted" , the soft deleted rows will never be fetch.

Now the question is:: what do you mean by : "when i try to remove a group from a user ?????"

Do you want to remove the association between the user and group??? if it's so then it means that the user2group table should not have any record for the given user and group.

That is why when u r trying "u.getGroups().remove(g);". It's deleting the record.

>Do you want to remove the association between the user and group???
yes, but using a "soft remove" - the entries should be kept in the database for later processing.
But as i understood hibernate needs to be informed of all object changes.
If you do not so, hibernate will still keep the old-collection cached containing still the just "removed" element, no?

Is there a way to force hibernate to reload the whole collection?
Would be a little bit inefficient, but working?[/code]

One possible way is to define an Event Listener (Extending from DefaultDeleteEventListener) and override the

method. Returning True from this method will veto the delete operation from happening. You also have the actual entity object , so you could actually do the update of setStatus("Deleted") in this interceptor rather than all over the code.

i tried this but it works only for buissines sobjects e.g. User/Group.
The entries from the user2grp table which are mapped in a collection Group.getMembers() have no real entity object.

Is there something similar for collections ?

Finally i found the correct solution :-)

@hibernate.sql-delete value=""

The "sql-delete" can be redefinded for the entitiy-class e.g. Group and for the collections too.
I my case i have to redefine the "delete-all" too oder maybe there is there a way disable the one-shot-delete?

This is working??.. how do you configure that??... I found a problem in all the solutions.. we do not manage the relations between objects.. let's say... the relational table in a ManyToMany.. how can we manage that?..
Hibernate should implement a way to do this.. There is no Real Solution to this problem.. every solution that i read, is a hack.