Postgres - move rows to different table - postgresql

Question

Using postgres 11 I would like to automatically move rows from one table to another. I have setup a query, trigger function, and trigger but my test inserts fail with '0 0' when the trigger is enabled.
source table to move rows from is 'cmdb'
destination table to move rows to is 'cmdb_attic'
condition is when column 'mgmt_ip' = ''
entire row should move
the table only contains 3 columns: 'hostname', 'mgmt_ip', 'os_type'
The trigger function code I have is:
BEGIN
WITH moved_rows AS (
DELETE FROM cmdb
WHERE mgmt_ip=''
RETURNING *
)
INSERT INTO cmdb_attic
SELECT * FROM moved_rows;
RETURN NULL;
END;
I defined a trigger under the table 'cmdb' that fires before on events insert.
When I do a test insert against table 'cmdb' I receive no error message, and nothing is inserted - into either table.
SOLUTION
I deleted my trigger function and trigger from pgAdmin and ran the code Bergi provided below into pgsql and it works.
CREATE FUNCTION redirect_to_attic() RETURNS TRIGGER
AS $$
BEGIN
IF NEW.mgmt_ip = '' THEN
INSERT INTO cmdb_attic VALUES (NEW.*);
RETURN NULL;
ELSE
RETURN NEW;
END IF;
END;
$$ LANGUAGE PLPGSQL;
CREATE TRIGGER redirect
BEFORE INSERT
ON cmdb
FOR EACH ROW
EXECUTE PROCEDURE redirect_to_attic();
EDIT 1 - trigger details from pgsql
inv_net=# select * from pg_trigger;
tgrelid | tgname | tgfoid | tgtype | tgenabled | tgisinternal | tgconstrrelid | tgconstrindid | tgconstraint | tgdeferrable | tginitdeferred | tgnargs | tgattr | tgargs | tgqual | tgoldtable | tgnewtable
---------+---------------+--------+--------+-----------+--------------+---------------+---------------+--------------+--------------+----------------+---------+--------+--------+--------+------------+------------
24623 | move_to_attic | 24618 | 7 | O | f | 0 | 0 | 0 | f | f | 0 | | \x | | |
(1 row)
EDIT 2 - test insert and select
With the trigger enabled, below is what I get. If I disable the trigger, my insert works and I can find that row in 'cmdb'.
inv_net=# INSERT INTO cmdb(hostname, mgmt_ip, os_type) VALUES ('testdevice', '', 'ios');
INSERT 0 0
inv_net=# select * from cmdb where hostname='testdevice';
hostname | mgmt_ip | os_type
----------+---------+---------
(0 rows)
inv_net=# select * from cmdb_attic where hostname='testdevice';
hostname | mgmt_ip | os_type
----------+---------+---------
(0 rows)
EDIT 3 - Steps Used to Create and Apply Trigger Function and Trigger in pgAdmin4
settings/tabs not listed were not adjusted
Tables > Trigger Functions > Create > Trigger Function
Type name 'move_to_attic'
Code tab: Insert code (from original post)
No other options/settings adjusted
Tables > cmdb > Triggers > Create > Triggers
Type name 'move_to_attic'
Definition tab: Trigger Enabled (yes), Row trigger (yes), Trigger Function public.move_to_attic
Events tab: Fires BEFORE, Events INSERT
Code tab: my code from the Trigger Function is there already
SQL tab: just says "-- No updates."
EDIT 4 - Output on SQL Tabs for Trigger and Trigger Function
trigger function (using Bergi's answer)
-- FUNCTION: public.move_to_attic()
-- DROP FUNCTION public.move_to_attic();
CREATE FUNCTION public.move_to_attic()
RETURNS trigger
LANGUAGE 'plpgsql'
COST 100
VOLATILE NOT LEAKPROOF
AS $BODY$BEGIN
IF NEW.mgmt_ip='' THEN
INSERT INTO cmdb_attic SELECT NEW;
RETURN NULL;
ELSE
RETURN NEW;
END IF;
END;$BODY$;
ALTER FUNCTION public.move_to_attic()
OWNER TO svc_netops_postgre;
trigger (applied to cmdb)
-- Trigger: move_to_attic
-- DROP TRIGGER move_to_attic ON public.cmdb;
CREATE TRIGGER move_to_attic
AFTER INSERT
ON public.cmdb
FOR EACH ROW
EXECUTE PROCEDURE public.move_to_attic();

Answer 1

basically I want to redirect an insert from cmdb to cmdb_attic where that condition is met
The trigger function for that should look like this:
BEGIN
IF NEW.mgmt_ip = '' THEN
INSERT INTO cmdb_attic VALUES (NEW.*);
RETURN NULL;
ELSE
RETURN NEW;
END IF;
END;
(online demo)