Right when you think you understand something (hehe)... I have a similar
problem, but I *thought* I solved it already. Anyways, I mapped my PK
column as an obj. attribute since I want to be able to access it in
queries and such. This works, right? I dont have to use the code given,
the class generation will create it correctly? If I want to change the
auto-gen PK (cant see why, just trying to understand) with the set
method, that will map correctly back to the database?
Thanks,
Scott
Twan Kogels wrote:
> Hello Andrus,
>
> Thanks for the pointer, it works perfect! For reference i used code from:
> <http://objectstyle.org/cayenne/lists/cayenne-user/2004/01/0004.html>
> and
> <http://www.objectstyle.org/cayenne/userguide/dataobjects/unmapped-keys.html>
>
> to get access to my primary key.
>
> Greetings,
> Twan
>
> At 18:15 28-6-2004, you wrote:
>
>> Hi there,
>>
>> the reason of not having a PK column in the object by default (you can
>> change this if you want) is more of a "philosophical" one -
>> autoincremented PK is meaningless within an object and is just a
>> database
>> convenience. So the rule of thumb is to not include such columns in the
>> object model, and let Cayenne handle them internally (encapsulated as
>> ObjectId). In case PK is meaningful (say "USER_TYPE_CODE" or something),
>> it can be mapped as an object property - Cayenne fully supports that.
>>
>> Now, if you want to use an autoincremented PK in your query, you can
>> still
>> do that. There were a few threads about it on the mailing list. For
>> example check out this one:
>>
>> http://objectstyle.org/cayenne/lists/cayenne-user/2004/01/0002.html
>>
>> Cheers,
>> Andrus
>>
>>
>> > Hello people,
>> >
>> > Today i downloaded and studied the "cayenne-web-app" example, which
>> uses
>> > struts en cayenne to create a webapplication which allows people to
>> > manage paintings, galleries and artists.
>> >
>> > It was a interesting and easy to understand example. But i've got a
>> > question about the example of something that isn't really clear for
>> me.
>> >
>> > In the example there is a Artist entity and a table ARTIST where the
>> > Artist entities are saved into. The ARTIST table contains of 3 rows,
>> > one of them is ID the primary key. My question is about this primary
>> > key:
>> >
>> > Why is the primary key not included as a attribute in the Artist
>> entity,
>> > is there maybe a special reason for not to do this?
>> >
>> > The reason for asking this is that it seems logical to include the
>> ID as
>> > a attribute of the Artist entity. Because for example when adding a
>> > painting to a artist, you could use:
>> > http://localhost:8080/struts/addPainting.do?artistid=2
>> > instead of the error phrone:
>> > http://localhost:8080/struts/addPainting.do?name=myname
>> > (myname doesn't seems to be unique, artistid is as a primary key
>> always
>> > unique)
>> >
>> > Best regards,
>> > Twan Kogels
>
>
>
>
>
>
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