Postgresql VARADIC function, need help (beginner) - arrays

Question

I´m new in programming with plpgsql and stored functions in postgresql.
I´ve programmed one function called this:
CREATE OR REPLACE FUNCTION public.uploadbutton(VARIADIC arr character varying[])
RETURNS text
LANGUAGE plpgsql
AS $function$DECLARE
arrayi ALIAS for $1;
result text;
begin
return result;
END;
$function$
;
As you can see, the function does not have many code. The problem is that i don´t really understand how to handle Arrays in Postgresql and plpgsql.
I need to split the array every 3 delimeters until the end of array, the array can have many inputs but minimum 3.
SELECT uploadbutton('59373033336415021231','5','a','59373033335915022fff','5','b')
Here an example for calling it.
The output should look like that:
('59373033336415021231','5','a')('59373033336415021231','5','a')
Can you teach me, how to handle that ?
Kind regards guys!
EDIT:
After getting this Result :
('59373033336415021231','5','a')('59373033336415021231','5','a')
I need to put every 3 parameters, and call a second function with the first part of the result as parameters. And the second Value have to be Int. This should look like this:
edit('59373033336415021231',5,'a')
and the same for the second part of the result
edit('59373033336415021231',5,'a')
I´m trying it at the moment and want to get the id of the first parameter with my edit() function. This is what i have:
CREATE OR REPLACE FUNCTION public.upload(string_in text)
RETURNS integer
LANGUAGE plpgsql
AS $function$DECLARE
string_in ALIAS FOR $1;
id integer;
begin
id= (select id from public.buttons where fbisn =
split_part(string_in,',',1));
return val;
end;
$function$
;
string_in is everytime the for clause of the first function is completed, the result string of that. This function will be called every time.
But currently, i will get no result.
Thanks for your help

Answer 1

Maybe a FOR LOOP using BY 3 is what you're struggling with
CREATE OR REPLACE FUNCTION public.uploadbutton(VARIADIC arr TEXT[])
RETURNS TEXT LANGUAGE plpgsql AS $$
DECLARE result TEXT DEFAULT '';
BEGIN
FOR i IN 1..array_length($1,1) BY 3 LOOP
result := result || '(' || array_to_string($1[i:i+2],',') || ')';
END LOOP;
RETURN result;
END;
$$;
Testing
SELECT uploadbutton(VARIADIC '{"59373033336415021231","5","a","59373033335915022fff","5","b"}'::text[]);
uploadbutton
------------------------------------------------------
(59373033336415021231,5,a)(59373033335915022fff,5,b)
(1 Zeile)
If you need the quotation marks ' in every element, just change the concatenation of the result variable accordingly:
result := result || E'(\'' || array_to_string($1[i:i+2],E'\',\'') || E'\')';
Edit: see comments
CREATE OR REPLACE FUNCTION public.uploadbutton(VARIADIC arr TEXT[])
RETURNS VOID LANGUAGE plpgsql AS $$
DECLARE slice TEXT[];
BEGIN
FOR i IN 1..array_length($1,1) BY 3 LOOP
slice := $1[i:i+2];
PERFORM edit(slice[1]::TEXT,slice[2]::INT,slice[3]::TEXT);
END LOOP;
END;
$$;

Answer 2

My answer may look ugly, but it works. You can optimize it if you want.
CREATE OR REPLACE FUNCTION uploadbutton(arr character varying[])
RETURNS text AS $$
DECLARE
arr_data character varying[] := arr;
array_len integer;
ar_data text;
incr INTEGER := 1;
result_data TEXT;
start_scope text := '(';
end_scope text := ')';
ins_incr integer := 1;
next_val text := '';
BEGIN
array_len := (select array_length(arr_data,1));
WHILE incr <= array_len LOOP
ar_data := CONCAT('''',arr_data[incr],'''');
IF (result_data IS NULL) THEN
result_data := CONCAT(result_data,'',ar_data);
ELSE
result_data := CONCAT(result_data,',',ar_data);
END IF;
ins_incr := ins_incr + 1;
IF (ins_incr = 4) THEN
result_data := CONCAT(start_scope,result_data,end_scope);
next_val := CONCAT(next_val,result_data);
result_data := NULL;
ins_incr := 1;
END IF;
incr := incr + 1;
END LOOP;
RETURN CONCAT(next_val,'(',result_data,')');
END $$
LANGUAGE plpgsql;
Sample:
SELECT uploadbutton(array ['59373033336415021231','5','a','59373033335915022fff','5','b','59373033335915022CCC','6','C','59373033335915022KKK','77','KK'])