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From "Patrick Linskey" <>
Subject Re: Please make Exceptions more useful...
Date Wed, 02 Apr 2008 15:41:43 GMT

Can you post the full stack trace?


On Wed, Apr 2, 2008 at 7:59 AM, David Goodenough
<> wrote:
> On Wednesday 02 April 2008, David Goodenough wrote:
>  > I just got an error message which said:-
>  >
>  > Exception in thread "main" <openjpa-1.0.2-r420667:627158 nonfatal general
>  > error> org.apache.openjpa.persistence.PersistenceException: java.util.Date
>  > cannot be cast to java.util.Collection
>  >
>  > In this (and the accompanying stack trace) there is no indication which
>  > Date object cannot be cast to a Collection.  Yes from the stack trace I
>  > know that I was trying to persist a particular root object, but I have no
>  > idea which class and field this error refers to.  Simply adding the class
>  > and field would make debugging so much easier.
>  >
>  > Then once I know which Date field it might be, I can start to try to work
>  > out why it wanted to cast it to a collection.  Presumably this was it was
>  > trying to map this to a particular table, or to a set of objects of a given
>  > type, and again it would be useful to know what application object as
>  > opposed to raw java class it was trying to map to.
>  >
>  > David
>  Well I dug a little further into this one, and I am confused.  It does indeed
>  have a Date object that is it trying to cast as a Collection.
>  From the FieldMapping object current at the time when it fails the field
>  in question is, and its definition is:-
>         @OneToMany(fetch=FetchType.LAZY,cascade=CascadeType.ALL) private List<Role>
>  roles;
>  Which is (quite properly) a Collection, and is not a date (yes I know, I
>  should not be using CascadeType.ALL, but at least here is does include
>  PERSIST.  As it happens this list is empty.
>  There is a Date, but it is in a superclass, its my @Version.  The superclass
>  is declared:-
>  @MappedSuperclass public class Basic extends Observed {
>         @Version @Temporal(TemporalType.TIMESTAMP) private Date version;
>  and there is the version field as well.  The outer class is declared:-
>  @Entity @Table(name="Roles") public class Role extends Basic {
>  All of which looks right to my untrained eye.  My guess is that for some
>  reason the system is getting confused about which class it is looking at,
>  the outer one or the super class but I do not know.  I have tried clearing
>  the binaries out from the Eclipse project, and rebuilding everything, but
>  that did not help.
>  Is this a known problem (in which case is there a workaround), if not
>  what do you need to help track it down.
>  David

Patrick Linskey
202 669 5907

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