way_to_wkt.sql

create or replace function way_to_wkt(way_id int)
returns text
language plpgsql as
$$
declare
    nodes bigint[] := (select nodes from planet_osm_ways where id = way_id);
    i smallint := 0;
    coords text[];
begin
    if array_length(nodes, 1) = 0 then
        return null;
    end if;
    while i < array_length(nodes, 1) loop
        coords := array_append(coords, (select lat || ' ' || lon from planet_osm_nodes where id = nodes[i]));
        i = i + 1;
    end loop;
    return 'MULTILINESTRING((' || array_to_string(coords, ', ') || '))';
end;
$$;