Call a Normal function inside a Trigger Function

On 16/04/2023 16:18 CEST FOUTE K. Jaurès <jauresfoute@gmail.com> wrote:

Is it possible to call a function inside a trigger function ?
Any idea or link are welcome. Thanks in advance

Depends on what you want to do with the return value. Use PERFORM to ignore
the result. [0]https://www.postgresql.org/docs/current/plpgsql-statements.html#PLPGSQL-STATEMENTS-GENERAL-SQL Use SELECT INTO to handle a single-row result. [1]https://www.postgresql.org/docs/current/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-ONEROW

PERFORM myfunc();
SELECT myfunc() INTO myresult;

[0]: https://www.postgresql.org/docs/current/plpgsql-statements.html#PLPGSQL-STATEMENTS-GENERAL-SQL
[1]: https://www.postgresql.org/docs/current/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-ONEROW

--
Erik

Hi

ne 16. 4. 2023 v 16:15 odesílatel FOUTE K. Jaurès <jauresfoute@gmail.com>
napsal:

Hello,

Is it possible to call a function inside a trigger function ?
Any idea or link are welcome. Thanks in advance

sure, there is not any limit.

Regards

Pavel

Can I have an example please? Or a link

On Sun, 16 Apr 2023, 17:08 Pavel Stehule, <pavel.stehule@gmail.com> wrote:

On 4/16/23 11:47, FOUTE K. Jaurès wrote:

Can I have an example please? Or a link

create table trg_test (id integer, fld_1 varchar, fld_2 boolean);

CREATE OR REPLACE FUNCTION public.child_fnc(token character varying)
RETURNS void
LANGUAGE plpgsql
AS $function$
BEGIN
IF token = 'yes' THEN
RAISE NOTICE 'Child';
END IF;
END;
$function$
;

CREATE OR REPLACE FUNCTION public.parent_fnc()
RETURNS trigger
LANGUAGE plpgsql
AS $function$
BEGIN
RAISE NOTICE 'Id is %', NEW.id;
RAISE NOTICE 'Fld_1 is %', NEW.fld_1;
RAISE NOTICE 'Parent';
PERFORM child_fnc('yes');
RETURN NEW;
END;
$function$
;

create trigger test_trg before insert on trg_test for each row execute
function parent_fnc();

insert into trg_test values (1, 'dog', 'f');
NOTICE: Id is 1
NOTICE: Fld_1 is dog
NOTICE: Parent
NOTICE: Child
INSERT 0 1

On Sun, 16 Apr 2023, 17:08 Pavel Stehule, <pavel.stehule@gmail.com
<mailto:pavel.stehule@gmail.com>> wrote:

Hi

ne 16. 4. 2023 v 16:15 odesílatel FOUTE K. Jaurès
<jauresfoute@gmail.com <mailto:jauresfoute@gmail.com>> napsal:

Hello,

Is it possible to call a function inside a trigger function ?
Any idea or link are welcome. Thanks in advance

sure, there is not any limit.

Regards

Pavel

Best Regards
--
Jaurès FOUTE

--
Adrian Klaver
adrian.klaver@aklaver.com

Hi

ne 16. 4. 2023 v 20:47 odesílatel FOUTE K. Jaurès <jauresfoute@gmail.com>
napsal:

Can I have an example please? Or a link

On Sun, 16 Apr 2023, 17:08 Pavel Stehule, <pavel.stehule@gmail.com> wrote:

Hi

ne 16. 4. 2023 v 16:15 odesílatel FOUTE K. Jaurès <jauresfoute@gmail.com>
napsal:

Hello,

Is it possible to call a function inside a trigger function ?
Any idea or link are welcome. Thanks in advance

sure, there is not any limit.

CREATE OR REPLACE FUNCTION allow_update(d date)
RETURNS bool AS $$
BEGIN
RETURN EXTRACT(YEAR FROM d) = EXTRACT(YEAR FROM current_date);
END;
$$ LANGUAGE plpgsql;

-- allow update record only from current year
CREATE OR REPLACE FUNCTION trg_func()
RETURNS TRIGGER AS $$
BEGIN
IF TG_OP = 'INSERT' THEN
IF NOT allow_update(NEW.inserted) THEN
RAISE EXCEPTION 'cannot insert';
END IF;
ELSE IF TG_OP = 'UPDATE' THEN
IF NOT allow_update(NEW.inserted) OR NOT allow_update(OLD.inserted)
THEN
RAISE EXCEPTION 'cannot update';
END IF;
ELSE
IF NOT allow_update(OLD.inserted) THEN
RAISE EXCEPTION 'cannot delete';
END IF;
END IF;
RETURN NULL;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER AFTER INSERT OR UPDATE OR DELETE ON sometab
FOR EACH ROW EXECUTE FUNCTION trg_func();

Regards

Pavel

p.s. You can do everything in trigger - Postgres is not Oracle where there
were some issues (if my memory serves well). There is only one risk -
possible recursion

Thanks @Adrian Klaver <adrian.klaver@aklaver.com>
It's clear for me now.

On Sun, 16 Apr 2023, 20:13 Adrian Klaver, <adrian.klaver@aklaver.com> wrote: