Re: [TRIGGER] Returning values from BEFORE UPDATE trigger, without using them

Hey Dmitriy,

thanks for your reply.

> I think, its would be better to use rule on update instead of the trigger
> in such case as you.

I've played the whole weekend with the rule-system, but it didn't work
for my case. I have a dynamic trigger, which takes cares about revision
of rows for every table, it is called from. It looks like that:

CREATE OR REPLACE FUNCTION versionizeContent()
RETURNS TRIGGER
AS $$
BEGIN

/* add new version in central register and insert new row */
NEW.revision := addContentRevision (OLD.content_id, OLD.revision,
sessval('user_id')::int));

EXECUTE 'INSERT INTO ' || quote_ident(TG_TABLE_NAME) ||
' SELECT (' || QUOTE_LITERAL(NEW) || '::' ||
quote_ident(TG_TABLE_NAME) ||').*' ;

RETURN NULL;

END;
$$ LANGUAGE 'plpgsql' VOLATILE;

Even if i drop the dynamic INSERT-Part and write it for every relation,
i wasn't able to figured out how to manipulate the NEW-Record.

The best i tried so far was:
CREATE RULE "versionize"
AS ON UPDATE
TO templates
DO INSTEAD
(
SELECT addContentRevision (OLD.content_id, OLD.revision,
sessval('user_id')::int) INTO NEW.revision;
INSERT INTO templates SELECT NEW.* RETURNING *;
);

But an Updates ends with the ERROR:
"ERROR: schema "*NEW*" does not exist"

Has anyone a hint how to manipulate the NEW record within an RULE?

Thanks,
Torsten