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From: Cecil Westerhof <Cecil@decebal.nl>
Newsgroups: comp.lang.java.programmer
Subject: Re: JPA and extra fields
Date: Mon, 17 Aug 2015 08:22:10 +0200
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On Friday 14 Aug 2015 04:30 CEST, Arne Vajhøj wrote:

> On 8/13/2015 2:12 PM, Cecil Westerhof wrote:
>> I am new to JPA. I have to migrate a JDBC application to JPA. For a
>> certain class there are some extra fields in the table that are not
>> in the class itself. (For example creation time, modification time
>> and user that created the entity.) Is it possible to keep those
>> fields in the table and updated, without putting the values in the
>> class?
>
> I can see different ways of moving forward.
>
> 1)
>
> Keep those fields out of the class an update them in the database
> via triggers.
>
> Possible create a view without those fields and have the entity map
> to that instead of the table.
>
> 2)
>
> Add the fields to the class but do not expose them in its
> public API. And let them be updated internally.
>
> Possible by mapping fields and either no getter/setter
> or protected.
>
> 3)
>
> Add the fields to the entity class the normal way
> but create a new domain class without the fields
> and convert from entity class to domain class when
> leaving DAL.

The first option seems the best to me. (But I am not sure it is
possible with all fields.) Is also depending on the database. The
application uses a CISC database. I am not sure if these have this
capability.

But I think I have to use the second possibility.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof