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From "jerome moliere" <>
Subject Re: Hook in the cayenne internals
Date Mon, 02 Apr 2007 09:02:24 GMT
2007/4/2, jerome moliere <>:
> Hi all,
> I'd like to show on a simple test the Cayenne equivalent for the Hibernate
> UserType, that is to say
> a way to map some SQL types with some user provided code...
> Example given is : my customers use sybase image type to store XML gzipped
> huge files...
> I'd like to be able to be able to store/read the XML transparently...Image
> type is a detail of implementation
> org.apache.cayenne.access.types.ExtendedType
> seems to be the Cayenne solution but there are no big details on this
> subject...
> Is the Cayenne source code my only source ?
> Moreover if you have UML sequence diagrams and other conception documents
> on Cayenne, I'd very happy to read them..

I 'll try to give your more clues...
In fact if I understand the ExtendedType machanism as plugged in the
DBadapters, a question still remains..
Let's imagine a small table schema:

(it will use a Postgresql syntax, with the bytea binary type)

CREATE TABLE PAITINGS_TBL(painting_id int primary key,painting_data bytea);

CREATE TABLE ARTISTS_BIO(artist_id int primary key, artist_text_bio bytea);

in this schema 2 tables with 2 BLOB fields, the first one is simply the JPEG
while the second is a long text with all the artist bio...

The extendedtype could permit me to change the Cayenne behavior but for all
bytea fields isn't it ?
I dont want to manage a JPEG in the same fashion as the authors bio...

Thanks for any help

Jerome Moliere - Mentor/J
auteur Eyrolles

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