app_challenge.sql

SELECT array_to_json(array_agg(row_to_json(t)))
FROM
  (SELECT id, text, Cast(created_at AS text),
                    likes_count,
                    CASE
                        WHEN l.value THEN TRUE
                        ELSE FALSE
                    END AS liked
   FROM posts
   LEFT OUTER JOIN
     (SELECT post_id,
             TRUE AS value
      FROM likes
      WHERE user_id = 1) AS l ON l.post_id = posts.id LIMIT 100) AS t;