generalized json joining

gistfile1.txt

fritzy=# select * from authors2;
 id |     name
----+--------------
  1 | Nathan Fritz
(1 row)

fritzy=# select * from books2;
 id |         title         | author_id
----+-----------------------+-----------
  1 | Happy Fun Times       |         1
  2 | Derpin with the Stars |         1
(2 rows)

fritzy=# select id, name, (select json_agg(row_to_json(book_r)) from (select title from books2 WHERE books2.author_id=authors2.id) book_r) AS books from authors2;
 id |     name     |                              books
----+--------------+------------------------------------------------------------------
  1 | Nathan Fritz | [{"title":"Happy Fun Times"}, {"title":"Derpin with the Stars"}]
(1 row)

fritzy=# select id, name, (select json_agg(row_to_json(book_r)) from (select id, title from books2 WHERE books2.author_id=authors2.id) book_r) AS books from authors2;
 id |     name     |                                     books
----+--------------+--------------------------------------------------------------------------------
  1 | Nathan Fritz | [{"id":1,"title":"Happy Fun Times"}, {"id":2,"title":"Derpin with the Stars"}]
(1 row)