Hello,
I have a problem in persisting/ retrieving an entity containing a
List<String> as field using OpenJPA Version 1.2.2. (I have to use OpenJPA
1.x and can not use OpenJPA 2.x).
I have searched in the archive of this mailing list and the web but didn't
found a solution for me. In general @PersistentCollection seems to work
here, but I still have problems:
I tried both ways for the configuration: Using Annotations in the entity
class or an orm.xml - it didn't change anything.
Using the orm.xml I marked this field with the <basic .../> tag, with
Annotations I used @PersistentCollection.
Persisting such an entity works fine, for both configuration ways OpenJPA
creates an additional table in the database that hold the lists values; if
an entity with such an list is persisted, I can see the data stored
correctly in the database (using a client tool to access the DB directly).
The problem arises when I try to fetch such objects out of the database
using a Query. (It seems to work sometimes for the PersistentManager.find
method when you know the PK for an object). When I execute a query
Query q = em.createQuery("SELECT myt FROM MYTABLE myt");
and then call q.getResultList()
I get an exception
Exception in thread "main" <openjpa-1.2.2-r422266:898935 nonfatal general
error> org.apache.openjpa.persistence.PersistenceException: java.lang.String
incompatible with org.apache.openjpa.enhance.PersistenceCapable
[...]
Caused by: java.lang.ClassCastException: java.lang.String incompatible with
org.apache.openjpa.enhance.PersistenceCapable
I observed that I can query for such entities without any problem when there
are no values for the List<String> field of the entity (when the list is
empty), but as soon as I add some values to it and persist such an entity, I
get this problem.
I would appreciate any help,
thank you very much!
Kind regards,
Tim
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