Hibernate version: 2.1.7
Name and version of the database you are using: Oracle 9i
I'm working with a database schema that was designed (but hasn't yet been implemented) before we decided to use Hibernate. It represents a system with several object types (e.g. Product, Contact, Distribution, Format, etc.), each of which we want to have Notes attached to.
I've been attempting to write my mapping documents and have come across a problem with this design. From reading the documentation, it is my understanding that using the collection mapping elements requires the use of the
key element. Creating a
map (or similar) that way implies a foreign key constraint on the child table.
In this case, however, the child table is represented in DDL as follows:
Code:
CREATE TABLE notes (
NOTE_ID NUMBER(9) NOT NULL,
REFERENCE_TYPE varchar2(50) NOT NULL,
REFERENCE_ID NUMBER(9) NOT NULL,
NOTE_TITLE varchar2(50) NULL,
NOTE_TEXT varchar2(1000) NULL,
DATE_CREATED timestamp NOT NULL,
AUTHOR_ID NUMBER(9) NOT NULL
);
ALTER TABLE notes
ADD ( PRIMARY KEY (NOTE_ID) ) ;
The idea is to use the
reference_type and
reference_id columns to describe the parent object of a particular Note.
reference_type will hold the (abbreviated) Java class name of the parent and
reference_id the parent's ID. (All IDs in the system are unique and generated by a single sequence.)
Because of this design choice, it's not possible to create a foreign key constraint for reference_id, because it won't always have the same parent table.
I've explored briefly the
where attribute for the
map element, but that doesn't seem designed to permit dynamic values or define this kind of loosely-tied foreign key.
Is it possible (or even sane) to map this using Hibernate? We went this route to avoid the creation of a note table for each type of object...
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