postgresql - trigger function with update not working with initial insert - postgresql

Question

I want to run a trigger each time a record is inserted or updated on table knowledgebase_messages which will vectorize the message column, using the joined pg_language_dictionary (e.g.: "French") for that message's locale_id.
Currently, the trigger working on row update, but not initial insert. Meaning, if I insert a row, then run a query to get records, updated the row in any way, or refresh the postgres UI, I see the vectorized value correctly there.
Trigger function:
runMessageVectorTriggerFn = 'CREATE OR REPLACE FUNCTION run_message_vector() ' +
'RETURNS TRIGGER ' +
'AS $BODY$ ' +
'BEGIN ' +
'IF pg_trigger_depth() <> 1 THEN ' +
'RETURN NEW; ' +
'END IF; ' +
'UPDATE knowledgebase_messages kbm ' +
'SET vector = to_tsvector(lang.pg_dictionary_name::regconfig, kbm.message) ' +
'FROM locales as loca ' +
'JOIN languages as lang ON loca.language_id = lang.id ' +
'WHERE kbm.locale_id = loca.id;' +
'RETURN NEW; ' +
'END; ' +
'$BODY$ LANGUAGE plpgsql';
Trigger:
runMessageVectorTrigger = 'CREATE TRIGGER run_message_vector AFTER INSERT OR UPDATE ON knowledgebase_messages ' +
'FOR EACH ROW EXECUTE PROCEDURE run_message_vector()';

Answer 1

When doing this in the BEFORE INSERT trigger, it doesn't update
the row being inserted because the row doesn't exist yet:
UPDATE knowledgebase_messages kbm...
Besides, it's not clear what is the intention in your UPDATE because
the WHERE clause seems to ignore the NEW row, as if it was implicit
that it was the target.
Anyway, instead of that, to change the row being inserted/updated, do
something along the lines of:
-- the SELECT must return 1 row, or in the worst case no row
-- otherwise an error will occur.
NEW.vector = (
SELECT
to_tsvector(lang.pg_dictionary_name::regconfig, NEW.message)
FROM locales as loca JOIN languages as lang
ON loca.language_id = lang.id
WHERE NEW.locale_id = loca.id
);
RETURN NEW;
both in BEFORE UPDATE and BEFORE INSERT cases.
Then you can remove this IF pg_trigger_depth() <> 1...