truncate all tables in a postgres schema

truncate.sql

DO $func$
BEGIN
    EXECUTE (
        SELECT
            'TRUNCATE TABLE ' || string_agg(oid::regclass::text, ', ') || ' CASCADE'
        FROM
            pg_class
        WHERE
            relkind = 'r'
            AND relnamespace = 'schema_name'::regnamespace);
END
$func$;