I have a class TimeUnit and another class TimePeriod. The way they are related are one to many, with a bidirectional relationship.

public class TimeUnit {
private List timePeriods;

}

public class TimePeriod {
private TimeUnit getTimeUnit();

}

TimeUnit class contains a list of TimePeriod instances, and each TimePeriod has a back reference to the containing TimeUnit object.

Using hibernate's examples I have set up the one to many relationship such that on the side of collection, I have inverse=true.

<list
name="timePeriods"
inverse="true"
>
<key column="TP_TU_ID"/>
<index column="TP_ORDER"/>
<one-to-many class="TimePeriod"/>
</list>

Because of inverse=true the order does not get saved for the timeperiod objects. What do I do in this case ? I need to have the list there, I need to also have timeperiod having reference to timeunit, and I need to also leave order manipulation up to hibernate.

How can I achieve all this ? Has anyone come across such case ? The hibernate-in-action says you cannot have an indexed collection on the inverse=true side. What's the workaround without losing any of my 3 goals ?

What we did was keep an int "orderIndex" member variable in what would be your TimePeriod class.

Add it as a <property> in your Hibernate mapping file to TimePeriod, but the accessors in the code like:



Good luck!

In HIbernate3 you can use:


<list name="timePeriods">
<key column="TP_TU_ID" not-null="true"/>
<index column="TP_ORDER"/>
<one-to-many class="TimePeriod"/>
</list>


And set the other end of the relationship insert="false" update="false"

The biggest difference I see in this and the mapping that I had posted, is that inverse=true is removed. Was that the idea ? If that is the case, I can remove the inverse attribute from my mapping also - without adding not-null="true" to <key> and not adding insert=false, update=false to many-to-one.

This is how the other side of association looks like in TimePeriod class
<many-to-one name="timeUnit"
class="TimeUnit"
column="TP_TU_ID"
not-null="true" />

I tried out the suggestion but it creates following sql
Hibernate: insert into TIME_UNITS (VERSION, NAME, TU_ID) values (?, ?, ?)
Hibernate: insert into TIME_PERIODS (VERSION, TP_TU_ID, TP_ORDER, TP_ID) values (?, ?, ?, ?)
Hibernate: insert into TIME_PERIODS (VERSION, TP_TU_ID, TP_ORDER, TP_ID) values (?, ?, ?, ?)
Hibernate: update TIME_PERIODS set TP_TU_ID=?, TP_ORDER=? where TP_ID=?
Hibernate: update TIME_PERIODS set TP_TU_ID=?, TP_ORDER=? where TP_ID=?

which is same as if I just remove inverse=true from my current mapping.
The question is should I remove the inverse? In that case hibernate would think the two associations are different and do the INSERT for one and UPDATE for another, for every timeperiod object I have. Is that good?