One
of the possible reasons for
org.hibernate.PropertyValueException: not-null property references a
null or transient value: com.server.X._YBackref
is
cascading same data multiple time.
For
Example you have have two classes
Class Person {
List<Car> carsOwned;
Car preferredCar;
….
}
Class Car {
….
}
And
the mapping
<bag name="carsOwned"
table="person_cars" access="property" cascade="all,delete-orphan">
<key column="person_id" not-null="true"
update="false" />
<one-to-many class="Car" />
</bag>
<many-to-one
name="preferredCar" class="Car" column="preferred_car_id"
not-null="false" unique="true"
cascade="all,delete-orphan" />
In
this case you may get the : not-null property references a null or transient
value: com.server.X._YBackref exception.
It
is because the same car is referred from two fields and both are trying to
save/update.
The
solution to this problem is change the preferredCar mapping as
<many-to-one
name="preferredCar" class="Car" column="preferred_car_id"
not-null="false" unique="true"
cascade="none" />