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Mapping Join Table with Collection of Components - Cascade Fails  RSS feed

Davis Ford
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Hi, I'm following the example in the the Java Persistence With Hibernate book on p. 307 "Mapping the join table to a collection of components. Below, I have a QPolicy class which can have a number of QRules assigned to it. There is an intermediate association class between a QPolicy and a QRule called QPolicyRule that also contains a severity. I've annotated it precisely how the book lists, which is supposed to manage cascades for me automatically. However, if I write the following code:

What I'm expecting is that hibernate will create a new row in QPolicy table, a new row in QPolicyRule, and a new row in QRule table. What actually happens is that hibernate creates a new row in QPolicy, QPolicyRule, and then throws an exception complaining that QRule is transient and that I must persist that object separately first.

But this is precisely the whole reason for embedding the collection of components, as the book clearly states:

The advantage of a collection of components is clearly the implicit lifecycle of the link objects. To create an association between a Category (QPolicy) and an Item (QRule), ad a new CategorizedItem (QPolicyRule) instance to the collection. To break the link, remove the element from the collection. No extra cascading settings are required, and the Java code is simplified.

What am I missing here?

Hibernate version:

Mapping documents:

The class QRule has no interesting mappings that are relevant, as it has no direct associations to QPolicy or QPolicyRule

Full stack trace of any exception that occurs:
Caused by: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: com.qcommon.repository.QRule
at org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:219)
at org.hibernate.type.EntityType.getIdentifier(EntityType.java:397)
at org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:87)
at org.hibernate.type.ComponentType.nullSafeSet(ComponentType.java:307)

Name and version of the database you are using:

The generated SQL (show_sql=true):

Note that it does not do the insert into the QRULE table, the next thing I get in the log debug is the exception complaining that the QRule object is transient. I know the object is transient, but I thought what the book describes would manage it in a cascading style.
Edvins Reisons
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Unless I missed it, you have not specified any cascading in the relationship mappings...
Don't get me started about those stupid light bulbs.
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