How to use a recursive query inside of a function? - postgresql

Question

I have a working recursive function down below that returns the hierarchy of a .Net Element, in this example 'ImageBrush'
WITH RECURSIVE r AS (
SELECT id, name, dependent_id, 1 AS level
FROM dotNetHierarchy
WHERE name = 'ImageBrush'
UNION ALL
SELECT g.id, lpad(' ', r.level) || g.name, g.dependent_id, r.level + 1
FROM dotNetHierarchy g JOIN r ON g.id = r.dependent_id
)
SELECT name FROM r;
Now I want to use it inside a function, where the input is a text like 'ImageBrush' which gets inserted in the WHERE statement of the recursive query.
The table dotNetHierarchy has 3 columns: id, name, dependent_id
The following didn´t work with PgAdmin just querying forever without an error:
CREATE OR REPLACE FUNCTION get_hierarchy(inp text) RETURNS
TABLE (id int, name text, id int, lev int) AS
$BODY$
DECLARE
BEGIN
WITH RECURSIVE r AS (
SELECT id, name, dependent_id, 1 AS level
FROM dotNetHierarchy
WHERE name = inp
UNION ALL
SELECT g.id, lpad(' ', r.level) || g.name, g.dependent_id, r.level + 1
FROM dotNetHierarchy g JOIN r ON g.id = r.dependent_id
)
SELECT name FROM r;
return;
END
$BODY$
LANGUAGE plpgsql;
I tried searching google for using recursive querys in functions, but the few results proved not to be working.
I would appreciate any help, thanks in advance.

Answer 1

Your function doesn't return anything. You would at least need a return query, but it's more efficient to use a language sql function to encapsulate a query:
CREATE OR REPLACE FUNCTION get_hierarchy(inp text)
RETURNS TABLE (id int, name text, id int, lev int) AS
$BODY$
WITH RECURSIVE r AS (
SELECT id, name, dependent_id, 1 AS level
FROM dotNetHierarchy
WHERE name = inp
UNION ALL
SELECT g.id, lpad(' ', r.level) || g.name, g.dependent_id, r.level + 1
FROM dotNetHierarchy g JOIN r ON g.id = r.dependent_id
)
SELECT name
FROM r;
$BODY$
LANGUAGE sql;