slugify.sql

CREATE OR REPLACE FUNCTION slugify("value" TEXT)
RETURNS TEXT AS $$
  WITH lowercased AS (
    SELECT lower(value) AS value
  ),
  translated AS (
    SELECT translate( value,
            'áàâãäåāăąèééêëēĕėęěìíîïìĩīĭḩóôõöōŏőùúûüũūŭůäàáâãåæçćĉčöòóôõøüùúûßéèêëýñîìíïş',
            'aaaaaaaaaeeeeeeeeeeiiiiiiiihooooooouuuuuuuuaaaaaaeccccoooooouuuuseeeeyniiiis'
        ) AS value
    FROM lowercased
  ),
  regexped AS (
      SELECT regexp_replace( value, '[^a-z0-9]+', ' ', 'g') AS value
      FROM translated
  ),
  trimmed AS (
      SELECT TRIM( value ) AS value
      FROM regexped
  ),
  replaced AS (
      SELECT REPLACE( value ,' ', '_') AS value
      FROM trimmed
  )
  SELECT value FROM replaced;
$$ LANGUAGE SQL STRICT IMMUTABLE;