Postgresql function (upsert and delete): how to pass a set of rows of table type to function call - sql

Question

I have a table
CREATE TABLE items(
id SERIAL PRIMARY KEY,
group_id INT NOT NULL,
item_id INT NOT NULL,
name TEXT,
.....
.....
);
I am creating a function that
takes set of row values for a single group_id, fail if multiple group_ids present in in input rows
compares it with matching values in the table (only for that group_id
updates changed values (only for the input group_id)
inserts new values
deletes table rows that are absent in the row input (compare rows with group_id and item_id)(only for the input group_id)
this is my function definition
CREATE OR REPLACE FUNCTION update_items(rows_input items[]) RETURNS boolean as $$
DECLARE
rows items[];
group_id_input integer;
BEGIN
-- get single group_id from input rows, fail if multiple group_id's present in input
-- read items of that group_id in table
-- compare input rows and table rows (of the same group_id)
-- create transaction
-- delete absent rows
-- upsert
-- return success of transaction (boolean)
END;
$$ LANGUAGE plpgsql;
I am trying to call the function in a query
select update_items(
(38,1,1283,"Name1"),
(39,1,1471,"Name2"),
(40,1,1333,"Name3")
);
I get the following error
Failed to run sql query: column "Name1" does not exist
I tried removing the id column values: that gives me the same error
What is the correct way to pass row values to a function that accepts table type array as arguments?

Answer 1

updates changed values
inserts new values deletes table rows that are
absent in the row input (compare rows with group_id and item_id)
If you want do upsert, you must upsert with unique constraint.
So there is two unique constraints. primary key(id), (group_id, item_id).
insert on conflict need consider these two unique constraint.
Since You want pass items[] type to the functions. So it also means that any id that is not in the input function arguments will also be deleted.
drop table if exists items cascade;
begin;
CREATE TABLE items(
id bigint GENERATED BY DEFAULT as identity PRIMARY KEY,
group_id INT NOT NULL,
item_id INT NOT NULL,
name TEXT
,unique(group_id,item_id)
);
insert into items values
(38,1,1283,'original_38'),
(39,1,1471,'original_39'),
(40,1,1333,'original_40'),
(42,1,1332,'original_42');
end;
main function:
CREATE OR REPLACE FUNCTION update_items (in_items items[])
RETURNS boolean
AS $FUNC$
DECLARE
iter items;
saved_ids bigint[];
BEGIN
saved_ids := (SELECT ARRAY (SELECT (unnest(in_items)).id));
DELETE FROM items
WHERE NOT (id = ANY (saved_ids));
FOREACH iter IN ARRAY in_items LOOP
INSERT INTO items
SELECT
iter.*
ON CONFLICT (id)
DO NOTHING;
INSERT INTO items
SELECT
iter.*
ON CONFLICT (group_id,
item_id)
DO UPDATE SET
name = EXCLUDED.name;
RAISE NOTICE 'rec.groupid: %, rec.items_id:%', iter.group_id, iter.item_id;
END LOOP;
RETURN TRUE;
END
$FUNC$
LANGUAGE plpgsql;
call it:
SELECT
*
FROM
update_items ('{"(38, 1, 1283, Name1) "," (39, 1, 1471, Name2) "," (40, 1, 1333, Name3)"}'::items[]);
references:
Iterating over integer[] in PL/pgSQL
How to match elements in an array of composite type?
IN vs ANY operator in PostgreSQL

Answer 2

Here's how I achieved UPSERT with DELETE missing rows, if anyone is looking to do the same.
CREATE OR REPLACE FUNCTION update_items(in_rows items[]) RETURNS INT AS $$
DECLARE
in_groups INTEGER[];
in_group_id INTEGER;
in_item_ids INTEGER[];
BEGIN
-- get single group id from input rows, fail if multiple group ids present in input
in_groups = (SELECT ARRAY (SELECT distinct(group_id) FROM UNNEST(in_rows)));
IF ARRAY_LENGTH(in_groups,1)>1 THEN
RAISE EXCEPTION 'Multiple group_ids found in input items: %', in_groups;
END IF;
in_group_id = in_groups[1];
-- delete items of this group that are absent in in_rows
in_item_ids := (SELECT ARRAY (SELECT (UNNEST(in_rows)).item_id));
DELETE FROM items
WHERE
master_code <> ANY (in_item_ids)
AND group_id = in_group_id;
-- upsert in_rows
INSERT INTO items
SELECT * FROM UNNEST(in_rows)
ON CONFLICT (group_id,item_d)
DO UPDATE SET
parent_group_id = EXCLUDED.parent_group_id,
mat_centre_id = EXCLUDED.mat_centre_id,
NAME = EXCLUDED.NAME,
opening_date = EXCLUDED.opening_date;
RETURN in_group_id;
-- return success of transaction (boolean)
END;
$$ LANGUAGE plpgsql;
This function removes rows that are missing from your in_rows