deleting tomany objects

[Mark Fraser-16]

Hello,

I am using Cayenned 2.0.4.

What is the proper way to delete the full collection of tomany objects
and have the target object's array correctly reflect the deletion?

The manual (http://cayenne.apache.org/doc20/deleting-objects.html)  says
to use dataContext.deleteObjects if you want to delete all objects in
the collection.

What it does not say is that the target object's array will still
contain references to objects that are scheduled for deletion (or have
been deleted after committal).

I have code like this:

 System.out.println("paintings: " + artist.getPaintingsArray().size());  
// "1"
 dataContext.deleteObjects(artist.getPaintingsArray());
 System.out.println("paintings: " + artist.getPaintingsArray().size());  
// "1"
 dataContext.commitChanges();
System.out.println("paintings: " + artist.getPaintingsArray().size());
// "1"


But if I try to delete the objects myself using an iterator as described
on that manual page I get a ConcurrencyModificationException--which is
warned about on that page.  It says this may result from the object
being deleted having a "nullify delete rule".  However in the modeler
the delete rule for both sides of the relationship is "No Action".

I would appreciate if someone could suggest how I am supposed to do this
(without switching Cayenne versions).

Thanks,

Mark

[Andrus Adamchik]

Hi Mark,

> However in the modeler the delete rule for both sides of the  
> relationship is "No Action".

you may want to change delete rule to "Nullify" from many side to one  
side of the relationship. Otherwise you'd have to explicitly unset the  
relationship before deleting an object.

Andrus

On Oct 21, 2009, at 10:37 AM, Mark Fraser wrote:

> Hello,
>
> I am using Cayenned 2.0.4.
>
> What is the proper way to delete the full collection of tomany  
> objects and have the target object's array correctly reflect the  
> deletion?
>
> The manual (http://cayenne.apache.org/doc20/deleting-objects.html)  
> says to use dataContext.deleteObjects if you want to delete all  
> objects in the collection.
> What it does not say is that the target object's array will still  
> contain references to objects that are scheduled for deletion (or  
> have been deleted after committal).
>
> I have code like this:
>
> System.out.println("paintings: " +  
> artist.getPaintingsArray().size());  // "1"
> dataContext.deleteObjects(artist.getPaintingsArray());
> System.out.println("paintings: " +  
> artist.getPaintingsArray().size());  // "1"
> dataContext.commitChanges();
> System.out.println("paintings: " +  
> artist.getPaintingsArray().size()); // "1"
>
>
> But if I try to delete the objects myself using an iterator as  
> described on that manual page I get a  
> ConcurrencyModificationException--which is warned about on that  
> page.  It says this may result from the object being deleted having  
> a "nullify delete rule".  However in the modeler the delete rule for  
> both sides of the relationship is "No Action".
>
> I would appreciate if someone could suggest how I am supposed to do  
> this (without switching Cayenne versions).
>
> Thanks,
>
> Mark
>
>
>
>
>
>

[Mark Fraser-16]

 >you may want to change delete rule to "Nullify" from many side to one
side of the relationship

No effect.

 >Otherwise you'd have to explicitly unset the relationship before
deleting an object.

I'm not sure what you mean by this.  Do you mean doing something like this?:

this.unsetReverseRelationship("toArtists", this.getToPaintings());

..in the tomany (painting) object?

I tried that and it didn't work (still getting
ConcurrentModificationException).

I just want to delete all of the objects and have it properly reflected
in the parent's array.  It seems like a very everyday operation.  Is it
really this difficult?

Thanks

Andrus Adamchik wrote:

> Hi Mark,
>
>> However in the modeler the delete rule for both sides of the
>> relationship is "No Action".
>
> you may want to change delete rule to "Nullify" from many side to one
> side of the relationship. Otherwise you'd have to explicitly unset the
> relationship before deleting an object.
>
> Andrus
>
> On Oct 21, 2009, at 10:37 AM, Mark Fraser wrote:
>
>> Hello,
>>
>> I am using Cayenned 2.0.4.
>>
>> What is the proper way to delete the full collection of tomany
>> objects and have the target object's array correctly reflect the
>> deletion?
>>
>> The manual (http://cayenne.apache.org/doc20/deleting-objects.html)  
>> says to use dataContext.deleteObjects if you want to delete all
>> objects in the collection.
>> What it does not say is that the target object's array will still
>> contain references to objects that are scheduled for deletion (or
>> have been deleted after committal).
>>
>> I have code like this:
>>
>> System.out.println("paintings: " +
>> artist.getPaintingsArray().size());  // "1"
>> dataContext.deleteObjects(artist.getPaintingsArray());
>> System.out.println("paintings: " +
>> artist.getPaintingsArray().size());  // "1"
>> dataContext.commitChanges();
>> System.out.println("paintings: " +
>> artist.getPaintingsArray().size()); // "1"
>>
>>
>> But if I try to delete the objects myself using an iterator as
>> described on that manual page I get a
>> ConcurrencyModificationException--which is warned about on that
>> page.  It says this may result from the object being deleted having a
>> "nullify delete rule".  However in the modeler the delete rule for
>> both sides of the relationship is "No Action".
>>
>> I would appreciate if someone could suggest how I am supposed to do
>> this (without switching Cayenne versions).
>>
>> Thanks,
>>
>> Mark
>>
>>
>>
>>
>>
>>
>
>

[Robert Zeigler-6]

Hi Mark,

The tips Andrus provided should work, in particular, making sure your  
delete rules are correct.
So the delete rule from for the relationship in the parent entity  
should (probably) be marked cascade (if the children can't exist w/out  
the parent; otherwise nullify), and the delete rule for the  
relationship on the child side should definitely be nullify. I've used  
this plenty of times and it works. :)  So if it's not working for you,  
maybe something else is going on? Are you using inheritance, by chance?

Robert

On Oct 22, 2009, at 10/2212:08 AM , Mark Fraser wrote:

> >you may want to change delete rule to "Nullify" from many side to  
> one side of the relationship
>
> No effect.
>
> >Otherwise you'd have to explicitly unset the relationship before  
> deleting an object.
>
> I'm not sure what you mean by this.  Do you mean doing something  
> like this?:
>
> this.unsetReverseRelationship("toArtists", this.getToPaintings());
>
> ..in the tomany (painting) object?
>
> I tried that and it didn't work (still getting  
> ConcurrentModificationException).
>
> I just want to delete all of the objects and have it properly  
> reflected in the parent's array.  It seems like a very everyday  
> operation.  Is it really this difficult?
>
> Thanks
>
> Andrus Adamchik wrote:
>> Hi Mark,
>>
>>> However in the modeler the delete rule for both sides of the  
>>> relationship is "No Action".
>>
>> you may want to change delete rule to "Nullify" from many side to  
>> one side of the relationship. Otherwise you'd have to explicitly  
>> unset the relationship before deleting an object.
>>
>> Andrus
>>
>> On Oct 21, 2009, at 10:37 AM, Mark Fraser wrote:
>>
>>> Hello,
>>>
>>> I am using Cayenned 2.0.4.
>>>
>>> What is the proper way to delete the full collection of tomany  
>>> objects and have the target object's array correctly reflect the  
>>> deletion?
>>>
>>> The manual (http://cayenne.apache.org/doc20/deleting- 
>>> objects.html)  says to use dataContext.deleteObjects if you want  
>>> to delete all objects in the collection.
>>> What it does not say is that the target object's array will still  
>>> contain references to objects that are scheduled for deletion (or  
>>> have been deleted after committal).
>>>
>>> I have code like this:
>>>
>>> System.out.println("paintings: " +  
>>> artist.getPaintingsArray().size());  // "1"
>>> dataContext.deleteObjects(artist.getPaintingsArray());
>>> System.out.println("paintings: " +  
>>> artist.getPaintingsArray().size());  // "1"
>>> dataContext.commitChanges();
>>> System.out.println("paintings: " +  
>>> artist.getPaintingsArray().size()); // "1"
>>>
>>>
>>> But if I try to delete the objects myself using an iterator as  
>>> described on that manual page I get a  
>>> ConcurrencyModificationException--which is warned about on that  
>>> page.  It says this may result from the object being deleted  
>>> having a "nullify delete rule".  However in the modeler the delete  
>>> rule for both sides of the relationship is "No Action".
>>>
>>> I would appreciate if someone could suggest how I am supposed to  
>>> do this (without switching Cayenne versions).
>>>
>>> Thanks,
>>>
>>> Mark
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>
>

[Mark Fraser-16]

Thanks Robert.  Changing to cascade on the parent did the trick....the
array members get removed just by calling deleteObjects on the data
context.  Makes sense but this isn't mentioned anywhere that I can see
in the deleteting objects documentation.

Mark

Robert Zeigler wrote:

> Hi Mark,
>
> The tips Andrus provided should work, in particular, making sure your
> delete rules are correct.
> So the delete rule from for the relationship in the parent entity
> should (probably) be marked cascade (if the children can't exist w/out
> the parent; otherwise nullify), and the delete rule for the
> relationship on the child side should definitely be nullify. I've used
> this plenty of times and it works. :)  So if it's not working for you,
> maybe something else is going on? Are you using inheritance, by chance?
>
> Robert
>
> On Oct 22, 2009, at 10/2212:08 AM , Mark Fraser wrote:
>
>> >you may want to change delete rule to "Nullify" from many side to
>> one side of the relationship
>>
>> No effect.
>>
>> >Otherwise you'd have to explicitly unset the relationship before
>> deleting an object.
>>
>> I'm not sure what you mean by this.  Do you mean doing something like
>> this?:
>>
>> this.unsetReverseRelationship("toArtists", this.getToPaintings());
>>
>> ..in the tomany (painting) object?
>>
>> I tried that and it didn't work (still getting
>> ConcurrentModificationException).
>>
>> I just want to delete all of the objects and have it properly
>> reflected in the parent's array.  It seems like a very everyday
>> operation.  Is it really this difficult?
>>
>> Thanks
>>
>> Andrus Adamchik wrote:
>>> Hi Mark,
>>>
>>>> However in the modeler the delete rule for both sides of the
>>>> relationship is "No Action".
>>>
>>> you may want to change delete rule to "Nullify" from many side to
>>> one side of the relationship. Otherwise you'd have to explicitly
>>> unset the relationship before deleting an object.
>>>
>>> Andrus
>>>
>>> On Oct 21, 2009, at 10:37 AM, Mark Fraser wrote:
>>>
>>>> Hello,
>>>>
>>>> I am using Cayenned 2.0.4.
>>>>
>>>> What is the proper way to delete the full collection of tomany
>>>> objects and have the target object's array correctly reflect the
>>>> deletion?
>>>>
>>>> The manual (http://cayenne.apache.org/doc20/deleting-objects.html)  
>>>> says to use dataContext.deleteObjects if you want to delete all
>>>> objects in the collection.
>>>> What it does not say is that the target object's array will still
>>>> contain references to objects that are scheduled for deletion (or
>>>> have been deleted after committal).
>>>>
>>>> I have code like this:
>>>>
>>>> System.out.println("paintings: " +
>>>> artist.getPaintingsArray().size());  // "1"
>>>> dataContext.deleteObjects(artist.getPaintingsArray());
>>>> System.out.println("paintings: " +
>>>> artist.getPaintingsArray().size());  // "1"
>>>> dataContext.commitChanges();
>>>> System.out.println("paintings: " +
>>>> artist.getPaintingsArray().size()); // "1"
>>>>
>>>>
>>>> But if I try to delete the objects myself using an iterator as
>>>> described on that manual page I get a
>>>> ConcurrencyModificationException--which is warned about on that
>>>> page.  It says this may result from the object being deleted having
>>>> a "nullify delete rule".  However in the modeler the delete rule
>>>> for both sides of the relationship is "No Action".
>>>>
>>>> I would appreciate if someone could suggest how I am supposed to do
>>>> this (without switching Cayenne versions).
>>>>
>>>> Thanks,
>>>>
>>>> Mark
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>

[Robert Zeigler-6]

Interesting.  It seems like it should have worked without the  
cascade... the nullify is what is supposed to do the trick... the  
cascade should just affect when you're deleting the parent, so you can  
delete the parent and all of the children at the same time.  I'd be  
curious to see you try the same code with 3.0M6, with the parent's  
delete rule unset (ie: no action), and the child's set to nullify.  In  
any event, glad things are working for you now.

Cheers,

Robert

On Oct 22, 2009, at 10/2212:40 AM , Mark Fraser wrote:

> Thanks Robert.  Changing to cascade on the parent did the  
> trick....the array members get removed just by calling deleteObjects  
> on the data context.  Makes sense but this isn't mentioned anywhere  
> that I can see in the deleteting objects documentation.
> Mark
>
> Robert Zeigler wrote:
>> Hi Mark,
>>
>> The tips Andrus provided should work, in particular, making sure  
>> your delete rules are correct.
>> So the delete rule from for the relationship in the parent entity  
>> should (probably) be marked cascade (if the children can't exist w/
>> out the parent; otherwise nullify), and the delete rule for the  
>> relationship on the child side should definitely be nullify. I've  
>> used this plenty of times and it works. :)  So if it's not working  
>> for you, maybe something else is going on? Are you using  
>> inheritance, by chance?
>>
>> Robert
>>
>> On Oct 22, 2009, at 10/2212:08 AM , Mark Fraser wrote:
>>
>>> >you may want to change delete rule to "Nullify" from many side to  
>>> one side of the relationship
>>>
>>> No effect.
>>>
>>> >Otherwise you'd have to explicitly unset the relationship before  
>>> deleting an object.
>>>
>>> I'm not sure what you mean by this.  Do you mean doing something  
>>> like this?:
>>>
>>> this.unsetReverseRelationship("toArtists", this.getToPaintings());
>>>
>>> ..in the tomany (painting) object?
>>>
>>> I tried that and it didn't work (still getting  
>>> ConcurrentModificationException).
>>>
>>> I just want to delete all of the objects and have it properly  
>>> reflected in the parent's array.  It seems like a very everyday  
>>> operation.  Is it really this difficult?
>>>
>>> Thanks
>>>
>>> Andrus Adamchik wrote:
>>>> Hi Mark,
>>>>
>>>>> However in the modeler the delete rule for both sides of the  
>>>>> relationship is "No Action".
>>>>
>>>> you may want to change delete rule to "Nullify" from many side to  
>>>> one side of the relationship. Otherwise you'd have to explicitly  
>>>> unset the relationship before deleting an object.
>>>>
>>>> Andrus
>>>>
>>>> On Oct 21, 2009, at 10:37 AM, Mark Fraser wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> I am using Cayenned 2.0.4.
>>>>>
>>>>> What is the proper way to delete the full collection of tomany  
>>>>> objects and have the target object's array correctly reflect the  
>>>>> deletion?
>>>>>
>>>>> The manual (http://cayenne.apache.org/doc20/deleting- 
>>>>> objects.html)  says to use dataContext.deleteObjects if you want  
>>>>> to delete all objects in the collection.
>>>>> What it does not say is that the target object's array will  
>>>>> still contain references to objects that are scheduled for  
>>>>> deletion (or have been deleted after committal).
>>>>>
>>>>> I have code like this:
>>>>>
>>>>> System.out.println("paintings: " +  
>>>>> artist.getPaintingsArray().size());  // "1"
>>>>> dataContext.deleteObjects(artist.getPaintingsArray());
>>>>> System.out.println("paintings: " +  
>>>>> artist.getPaintingsArray().size());  // "1"
>>>>> dataContext.commitChanges();
>>>>> System.out.println("paintings: " +  
>>>>> artist.getPaintingsArray().size()); // "1"
>>>>>
>>>>>
>>>>> But if I try to delete the objects myself using an iterator as  
>>>>> described on that manual page I get a  
>>>>> ConcurrencyModificationException--which is warned about on that  
>>>>> page.  It says this may result from the object being deleted  
>>>>> having a "nullify delete rule".  However in the modeler the  
>>>>> delete rule for both sides of the relationship is "No Action".
>>>>>
>>>>> I would appreciate if someone could suggest how I am supposed to  
>>>>> do this (without switching Cayenne versions).
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Mark
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>

[Mark Fraser-16]

I would like to try that but when I tried moving to 3.x too many things
broke and I gave up.  I started with 2.x because I usually go with the
"stable" version and being new to Cayenne at the time I didn't know
better.  Now I read on this list on a regular basis how stable 3.x is.  
If it had been listed as stable several months ago when I started I
would have avoided a lot of headaches.  What is the delay with declaring
3.x stable?



Robert Zeigler wrote:

> Interesting.  It seems like it should have worked without the
> cascade... the nullify is what is supposed to do the trick... the
> cascade should just affect when you're deleting the parent, so you can
> delete the parent and all of the children at the same time.  I'd be
> curious to see you try the same code with 3.0M6, with the parent's
> delete rule unset (ie: no action), and the child's set to nullify.  In
> any event, glad things are working for you now.
>
> Cheers,
>
> Robert
>
> On Oct 22, 2009, at 10/2212:40 AM , Mark Fraser wrote:
>
>> Thanks Robert.  Changing to cascade on the parent did the
>> trick....the array members get removed just by calling deleteObjects
>> on the data context.  Makes sense but this isn't mentioned anywhere
>> that I can see in the deleteting objects documentation.
>> Mark
>>
>> Robert Zeigler wrote:
>>> Hi Mark,
>>>
>>> The tips Andrus provided should work, in particular, making sure
>>> your delete rules are correct.
>>> So the delete rule from for the relationship in the parent entity
>>> should (probably) be marked cascade (if the children can't exist
>>> w/out the parent; otherwise nullify), and the delete rule for the
>>> relationship on the child side should definitely be nullify. I've
>>> used this plenty of times and it works. :)  So if it's not working
>>> for you, maybe something else is going on? Are you using
>>> inheritance, by chance?
>>>
>>> Robert
>>>
>>> On Oct 22, 2009, at 10/2212:08 AM , Mark Fraser wrote:
>>>
>>>> >you may want to change delete rule to "Nullify" from many side to
>>>> one side of the relationship
>>>>
>>>> No effect.
>>>>
>>>> >Otherwise you'd have to explicitly unset the relationship before
>>>> deleting an object.
>>>>
>>>> I'm not sure what you mean by this.  Do you mean doing something
>>>> like this?:
>>>>
>>>> this.unsetReverseRelationship("toArtists", this.getToPaintings());
>>>>
>>>> ..in the tomany (painting) object?
>>>>
>>>> I tried that and it didn't work (still getting
>>>> ConcurrentModificationException).
>>>>
>>>> I just want to delete all of the objects and have it properly
>>>> reflected in the parent's array.  It seems like a very everyday
>>>> operation.  Is it really this difficult?
>>>>
>>>> Thanks
>>>>
>>>> Andrus Adamchik wrote:
>>>>> Hi Mark,
>>>>>
>>>>>> However in the modeler the delete rule for both sides of the
>>>>>> relationship is "No Action".
>>>>>
>>>>> you may want to change delete rule to "Nullify" from many side to
>>>>> one side of the relationship. Otherwise you'd have to explicitly
>>>>> unset the relationship before deleting an object.
>>>>>
>>>>> Andrus
>>>>>
>>>>> On Oct 21, 2009, at 10:37 AM, Mark Fraser wrote:
>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> I am using Cayenned 2.0.4.
>>>>>>
>>>>>> What is the proper way to delete the full collection of tomany
>>>>>> objects and have the target object's array correctly reflect the
>>>>>> deletion?
>>>>>>
>>>>>> The manual
>>>>>> (http://cayenne.apache.org/doc20/deleting-objects.html)  says to
>>>>>> use dataContext.deleteObjects if you want to delete all objects
>>>>>> in the collection.
>>>>>> What it does not say is that the target object's array will still
>>>>>> contain references to objects that are scheduled for deletion (or
>>>>>> have been deleted after committal).
>>>>>>
>>>>>> I have code like this:
>>>>>>
>>>>>> System.out.println("paintings: " +
>>>>>> artist.getPaintingsArray().size());  // "1"
>>>>>> dataContext.deleteObjects(artist.getPaintingsArray());
>>>>>> System.out.println("paintings: " +
>>>>>> artist.getPaintingsArray().size());  // "1"
>>>>>> dataContext.commitChanges();
>>>>>> System.out.println("paintings: " +
>>>>>> artist.getPaintingsArray().size()); // "1"
>>>>>>
>>>>>>
>>>>>> But if I try to delete the objects myself using an iterator as
>>>>>> described on that manual page I get a
>>>>>> ConcurrencyModificationException--which is warned about on that
>>>>>> page.  It says this may result from the object being deleted
>>>>>> having a "nullify delete rule".  However in the modeler the
>>>>>> delete rule for both sides of the relationship is "No Action".
>>>>>>
>>>>>> I would appreciate if someone could suggest how I am supposed to
>>>>>> do this (without switching Cayenne versions).
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Mark
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>
>

[Aristedes Maniatis-2]

On 22/10/09 5:33 PM, Mark Fraser wrote:
> What is the delay with declaring 3.x stable?

There is discussion about getting beta 1 out the door in a matter of days. Or a week. But very soon :-)

Ari

--

-------------------------->
Aristedes Maniatis
GPG fingerprint CBFB 84B4 738D 4E87 5E5C  5EFA EF6A 7D2E 3E49 102A