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Subject: Re: ToManyList cannot be instantiated with a
 list.getClass().newInstance()
From: Andrus Adamchik <andrus@objectstyle.org>
In-Reply-To: <5010F23E.7080904@telia.com>
Date: Fri, 27 Jul 2012 10:30:37 +0300
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To: user@cayenne.apache.org

Hi Tomas,

> PS ! Have a look at the application at =
http://blog.stenlund.cc/?page_id=3D26, a cross country skiing time =
recording and competition management application using Apache Pivot and =
Cayenne. It is a pleasure working with those two frameworks, among =
other. DS!


Nice! :)

Andrus

On Jul 26, 2012, at 10:31 AM, Tomas Stenlund wrote:

> Hi Andrus,
>=20
> thanks for taking your time to give your opinion.
>=20
> Yes, I have come to the same conclusion as you. The TooMany list =
outside cayenne don't really mean anything. Since Pivot is able to =
swallow List:s right out of the box to display them in List-, =
Tablewiddgets etc. I got led down the wrong alley. Looking into the =
source of Pivot it actually does some manipulating with the List and =
creation of new Lists that will not work with cayenne. I have also =
discussed this with the guys at the Pivot  list.
>=20
> So, now I convert the Cayenne TooManyList to simple "Java lists" and =
send them into Pivot instead. So when the Pivot dialogues want to change =
some data in the CayenneObjects it goes through getters/setters I can =
just then commit the changes after the user for instance press "Save". =
So it works well.
>=20
> Cheers,
>=20
> Tomas
>=20
> PS ! Have a look at the application at =
http://blog.stenlund.cc/?page_id=3D26, a cross country skiing time =
recording and competition management application using Apache Pivot and =
Cayenne. It is a pleasure working with those two frameworks, among =
other. DS!
>=20
> On 07/23/2012 03:39 PM, Andrus Adamchik wrote:
>> Not familiar with Pivot, so not sure what its expectations are. But =
creating a ToManyList outside Cayenne generally doesn't seem like a good =
idea. Maybe what you doing as a workaround is perfectly valid. So what =
is the purpose of creating a new list by Pivot and what happens to that =
list after that? Is there an attempt to persist it afterwords?
>>=20
>> Cheers,
>> Andrus
>>=20
>>=20
>> On Jul 12, 2012, at 8:46 AM, Tomas Stenlund wrote:
>>=20
>>> Hi,
>>>=20
>>> I'm using Cayenne 3.1B1 and Pivot 2.0.2 as a GUI and have come =
across something which I would gladly have some good suggestions around.
>>>=20
>>> The automatically generated getters for the relationships sometimes =
returns a ToManyList of objects. To be able to use that list directly in =
Pivot:s widgets I have to wrap it with a ListAdapter. So, now for the =
cayenne questions, it seems that ToManyList does not have an empty =
constructor (maybe it does not have one because it does not really mean =
anything in the ToMany relationship) causing a call to the =
list.getClass().newInstance() that the ListAdapter in pivot does to =
create a new empty list of the same type to throw the =
InstantiationException.
>>>=20
>>> It might be that the ListAdapter is wrongly implemented to assume =
that the List:s always have an empty constructor or something else. Any =
ideas ? For now I just create a new list (ArrayList or something =
similar) and fills it up with the objects in the ToManyList to send it =
into Pivot to make it work, but it does seem to give an ugly solution =
moving from one list type to another just to come around this.
>>>=20
>>> Thanks for any comments,
>>>=20
>>> Cheers,
>>>=20
>>> Tomas
>>>=20
>>=20
>=20