Re: How to create Meaningful Primary Keys?

From: Pierre Lavignotte (pierre.lavignott..mail.com)
Date: Mon Feb 02 2009 - 08:21:17 EST

  • Next message: Alessio Giovanni Baroni: "Re: How to create Meaningful Primary Keys?"

    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 <niparas..mail.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 <niparas..mail.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
    > > >
    > > >
    >
    >

    This archive was generated by hypermail 2.0.0 : Mon Feb 02 2009 - 08:21:57 EST