Postgresql function loop through input arguments and append to hstore - postgresql

Question

I'm wondering if it is possibile in PostgreSQL to loop through all available input parameters of the current function and append these arguments (key=>value) to a hstore variabele.
hstore-key = the name of the given input argument/parameter....
hstore-Value = the value of the given argument...
For example:
-- input for call function with input arguments
SELECT append_hstore_from_args ('val1','val22','val333');
CREATE OR REPLACE FUNCTION append_hstore_from_args (IN param1 text, IN param2 text, IN param3 text)
RETURNS text AS
$BODY$
DECLARE
new_h hstore;
BEGIN
-- below is pseudo
for p in all_params
loop
new_h := new_h+"$p->name"=>"$p->value";
end loop;
-- at this point the variable new_h (hstore) should contain
-- '"param1"=>"val1","param2"=>"val22","param3"=>"val333"'
-- call function with hstore argument
perform test.func123(new_h);
RETURN;
END;
$BODY$
LANGUAGE plpgsql VOLATILE SECURITY DEFINER
I've searched, but unfortunately didn't find any hints on how to get this done in PostgreSQL.

Answer 1

I assume that it is a question of how to handle a variable number of function arguments.
Variadic arguments are accessible inside a function as an array. You can use FOREACH ... LOOP:
create or replace function strings_to_hstore(args variadic text[])
returns hstore language plpgsql as $$
declare
idx int = 0;
str text;
hst hstore;
res hstore = '';
begin
foreach str in array args loop
idx:= idx+ 1;
execute format($f$select 'param%s=>%s'$f$, idx, str) into hst;
res:= res|| hst;
end loop;
return res;
end $$;
select strings_to_hstore('one', 'two');
strings_to_hstore
----------------------------------
"param1"=>"one", "param2"=>"two"
(1 row)
select strings_to_hstore('red', 'green', 'blue');
strings_to_hstore
------------------------------------------------------
"param1"=>"red", "param2"=>"green", "param3"=>"blue"
(1 row)
If you wanted to define hstore keys in the argument list:
create or replace function strings_with_keys_to_hstore(args variadic text[])
returns hstore language plpgsql as $$
declare
idx int = 0;
key text;
str text;
hst hstore;
res hstore = '';
begin
foreach str in array args loop
idx:= idx+ 1;
if idx & 1 then
key:= str;
else
execute format($f$select '%s=>%s'$f$, key, str) into hst;
res:= res|| hst;
end if;
end loop;
return res;
end $$;
select strings_with_keys_to_hstore('key1', 'val1', 'key2', 'val2');
strings_with_keys_to_hstore
--------------------------------
"key1"=>"val1", "key2"=>"val2"
(1 row)
Note, that there are standard hstore functions: hstore(text[]) and hstore(text[], text[]).