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From Nikos Paraschou <nipar...@gmail.com>
Subject Re: How to create Meaningful Primary Keys?
Date Mon, 02 Feb 2009 20:44:53 GMT
The point about saying "no to meaningful pointers" is very clear.

Thank you for your replies and advice. I will perform some tests as soon
as I can and come back with feedback, if I encounter any problems.

Regards,
Nikos


Στις 02-02-2009, ημέρα Δευ, και ώρα 14:21 +0100, ο/η Pierre Lavignotte
έγραψε:
> Here is what I use when I want to get Recomaster entity with primary key =
> id :
> 
>         Recomaster recomaster = (Recomaster)
> DataObjectUtils.objectForPK(context, Recomaster.class, id);
> 
> And in the Recomaster class, I also have a method that gives me the primary
> key :
> 
>     public Integer getId() {
>         return DataObjectUtils.intPKForObject(this);
>     }
> 
> There are similar methods for when primary key is not an integer value.
> 
> Cheers
> 
> Cordialement,
> Pierre Lavignotte
> Ingénieur Conception & Développement
> http://pierre.lavignotte.googlepages.com
> 
> 
> On Mon, Feb 2, 2009 at 2:14 PM, Νίκος Παράσχου <niparasc@gmail.com>
wrote:
> 
> > First of all thank you for your replies.
> >
> > I have the following table:
> >
> > Vehicle (
> >       plate_num CHAR(10) NOT NULL,
> >       mixed_weight DOUBLE PRECISION NOT NULL,
> >       type CHAR(30) NOT NULL,
> >       manufacturer CHAR(20),
> >       PRIMARY KEY (plate_num)
> > )
> >
> > In Cayenne Modeller I have the dbEntity "vehicle" with all the above
> > attributes (plate_num is check as PK). There is also the objEntity
> > "Vehicle" with all the above attributes except the PK (plate_num).
> >
> > I want to select the type of the vehicle with plate_num = "AHZ-4141".
> >
> > Could you please post some code samples? I have tried so many things
> > (with DataObjectUtils too) but still no success.
> >
> > Thank you,
> > Nikos
> >
> > Στις 02-02-2009, ημέρα Δευ, και ώρα 12:49 +0100, ο/η Pierre
Lavignotte
> > έγραψε:
> > > Hi Nikos,
> > >
> > > If you need PK for all your tables, then maybe you need to generate them.
> > > But if you only need to use them for a couple tables then you should look
> > at
> > > DataObjectUtils class.
> > >
> > >
> > > Cheers,
> > > Pierre
> > >
> > > Cordialement,
> > > Pierre Lavignotte
> > > Ingénieur Conception & Développement
> > > http://pierre.lavignotte.googlepages.com
> > >
> > >
> > > On Mon, Feb 2, 2009 at 12:35 PM, Νίκος Παράσχου <niparasc@gmail.com>
> > wrote:
> > >
> > > > Hello,
> > > >
> > > > It is the first time I am using cayenne and I have some questions
> > > > regarding the primary keys.
> > > >
> > > > What I want to do is select some rows of a table where the PK has a
> > > > specific value. The problem is I can't access the PK. I can specify
> > > > qualifiers only with the non-PK columns. The PKs I am using have some
> > > > meaning (they are not just numbers) so it is very important to be able
> > > > to use them.
> > > >
> > > > How can I add the PK to the fields of the Object Entities?
> > > >
> > > > In this page
> > http://cayenne.apache.org/doc20/primary-key-generation.html
> > > > the answer is to create a Meaningful Primary Key.
> > > >
> > > > How can I create Meaningful Primary Keys?
> > > >
> > > > Are there any security issues when using Meaningful Primary Keys?
> > > >
> > > > Thank you for your time,
> > > > Nikos
> > > >
> > > >
> >
> >


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