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Hibernate version:
3.x

Mapping documents:
<class name="User" table="user">
<id name="id" column="user_id">
<generator class="IdGenerator">
<param name="sequence_name">main_sequence</param>
</generator>
</id>
<set name="responses" cascade="save-update" inverse="true" access="field">
<key column="user_id" not-null="true"/>
<one-to-many class="Response"/>
</set>
</class>

<class name="Response" table="response">
<composite-id name="id" class="Response$Identifier">
<key-property name="userId" type="long" column="user_id"/>
<key-property name="questionId" type="long" column="question_id"/>
<key-property name="answerId" type="long" column="answer_id"/>
</composite-id>

<property name="response" column="response_text" access="field"/>

<many-to-one name="question" column="question_id" class="Question" access="field" cascade="none" insert="false" update="false" />
<many-to-one name="answer" column="answer_id" class="Answer" access="field" cascade="none" insert="false" update="false"/>
<many-to-one name="user" column="user_id" class="User" access="field" cascade="none" insert="false" update="false"/>

</class>


Hi,

I'm having trouble working with a composite-id. The problem is that if I attempt to save a user object that contains a number of responses, the cascade to responses does not work. It doesn't know that the user object has been saved, so it can't create the responses successfully with a null user id.

The documentation indicates that one has to set the fields on a composite id in the application code. However, it doesn't seem possible to handle all the relevant cases.

A new user object. If in my DAO I recognize that it's a new user, i can iterate through responses, set the new user id and save them. However, if it's not a new user, I don't know how to figure out the persistance. Some responses that are in the db may need to be deleted, some added/updated . I can't execute the delete first, because then i've lost the new data as well. Even if i could detach the responses from the session, if i attempt to add any with the same key, it'll give me an error about different objects with the same key being added to the session.

I would really like hibernate to take care of this association, but unless I'm missing something, it can not. Can anyone point me in the right direction?

Just a note, adding a generic pkey to the response table is not an option.

thanks

Try key-many-to-one instead of key-property:

Since I dont want to have access="field", below code uses setters/getters. You can replace them appropriately.




If the user & response already existed and you want add new response's, delete some then check the below code. Also I suggest you override equals() and hashCode() in Response$Identifier class to make this work.

I apprecidate the help. I've got it working now, but it's a lot more manual work than i was hoping for. Since knowing what to delete is somewhat hard (the user is only gonna submit what they want, not all the changes) I had to write a lot of code to figure out what to remove, what to add and what to update.

I was really hoping i could clear out all the responses, and add a new set of responses and hibernate would at least know to delete all the old stuff, and add this new stuff, and even better would be to delete the stuff that isn't valid anymore and make the updates/inserts.

Oh well, at least I have something working.

thanks again