WP-API/WP-API — pull request #391 by maxcutler (2014-08-01 17:32:04+00:00)
Title: post 'parent' value should be null rather than zero if unset

Having a field be either an integer or a nested object makes parsing more complicated. Furthermore, knowing that a parent ID of "0" means that a post has no parent is WordPress inside knowledge that should not leak through the API.