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Hibernate version:
3.1

Mapping documents:
<list name="values" cascade="all-delete-orphan" lazy="true" inverse="false" >
<key column="scale_id" not-null="true"/>
<list-index column="value_position" />
<one-to-many entity-name="scale_value" />
</list>

The above mapping gives this error:

java.lang.ClassCastException: org.hibernate.property.BackrefPropertyAccessor$1
at org.hibernate.type.LongType.set(LongType.java:42)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:83)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:65)
at org.hibernate.loader.Loader.bindPositionalParameters(Loader.java:1513)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1575)
at org.hibernate.loader.Loader.doQuery(Loader.java:661)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
at org.hibernate.loader.Loader.doList(Loader.java:2144)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2028)
at org.hibernate.loader.Loader.list(Loader.java:2023)
at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:95)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1569)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283)

If I remove the not-null constraint from the <key> element, it works fine.

I am simply retrieving all instances of the value classing using a criteria.

Thanks.

Does your scale_value entity have a mapping to its parent or to its parent ID? Looks like hibernate trying to set a long but is given the parent object instead.

Hey. Yeah, there's a mapping from the values entity back to the owning entity:

<many-to-one name="scale" entity-name="scale" insert="false" update="false" not-null="true">
<column name="scale_id"/>
</many-to-one>

(The mapping snippet from my original post was from scale to value)

Your situation is almost straight out of the hibernate docs:


Try removing some of the extra attributes from the parent mapping (i.e. cascade="all-delete-orphan" lazy="true" inverse="false") to make yours closer to theirs.

Yeah, I did try that to no avail.

Same result if mapping is:

<!-- cascade="all-delete-orphan" lazy="true" inverse="false" -->
<list name="values">
<key column="scale_id" not-null="true" />
<list-index column="value_position" />
<one-to-many entity-name="scale_value" />
</list>

Which is almost verbatim from the book:

<list name="bids">
<key column="ITEM_ID" not-null="true"/>
<list-index column="BID_POSITION"/>
<one-to-many class="Bid"/>
</list>

Except the book uses class and I'm using entity-name.

My mapping from the list-member back to the owner is basically the same also:

(mine)
<many-to-one name="scale" entity-name="scale" insert="false" update="false" not-null="true">
<column name="scale_id"/>
</many-to-one>

(the Book's)
<many-to-one name="item" column="ITEM_ID" class="Item" not-null="true" insert="false" update="false" />

I guess I can try moving the column element into an attribute.

This appears to happen when doing a criteria fetch for all the objects of a type, when that type is used as a list member on another object. Admittedly a pretty edge use case. In any case, if you really need to do that, you can avoid the Backref error by making the key to the list nullable (both in the mapping and in your DDL).