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From Thomas Risberg <thomas.risb...@tridb.com>
Subject Re: state-of-the art attribute initialization in persistent pojos?
Date Thu, 12 Apr 2007 17:29:01 GMT
I thought the no-arg constructor had to be public or protected - see
"2.1 Requirements on the Entity Class" section where this is mentioned. 
If that's not the case so much better, but I have been adding a
protected constructor in my entities.

Cheers,
Thomas


Craig L Russell wrote:
> Hi Hans,
>
> On Apr 12, 2007, at 8:43 AM, Hans J. Prueller wrote:
>
>> hi,
>> as you know I am switching from EJB2.1 CMP to JPA (OpenJPA). I'd like
>> to know the preferred way to perform attribute initialisation of
>> newly created entity instances, e.g. we initialized our EJB2.1 CMP
>> entity beans with
>>
>> ejbCreate(String cid, Integer someOtherValue)
>> {
>> setabc();
>> setdef();
>> }
>>
>> //and ejbPostCreate optionally
>>
>> as far as I know, the JPA spec requires a no-arg constructor - so
>> when providing a constructor with the same args that we have used in
>> ejbCreate before, we cannot ensure that some developer calls the
>> no-arg constructor by default.
>
> The no-arg constructor can be private. The reason it's required is so
> the implementation doesn't have to guess what the right values are for
> final variables. But there's no requirement to make this constructor
> available to your applications.
>>
>> is there any other-more elegant way to force new entity instance
>> initialization?
>
> There's no requirement for an ejbCreate and a separate ejbPostCreate
> for relationships. So you are really free to do whatever you like for
> the application contract. Have as many constructors as you like and
> put whatever initialization into them.
>
> Just don't initialize the values of generated fields...
>
> Craig
>>
>> regards,
>>
>> HANS
>>
>> ===========================
>> virtually hanzz...
>>
>>  <http://hanzz.zapto.org> http://hanzz.zapto.org (personal)
>>  <http://www.cse.dmu.ac.uk/~hansp> http://www.cse.dmu.ac.uk/~hansp
>> (research)
>
> Craig Russell
> Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
> 408 276-5638 mailto:Craig.Russell@sun.com
> P.S. A good JDO? O, Gasp!
>


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