From d802d709c7357e8f310f7f6569666a5ff7187fab Mon Sep 17 00:00:00 2001
From: Gary Pendergast <gary@pento.net>
Date: Fri, 13 Jul 2018 06:14:25 +0000
Subject: [PATCH] REST API: Expose revision count and last revision ID on Post
 response

So that REST API clients can show appropriate UI for a post's revisions, it needs to know how many revisions the post has, and what the latest revision ID is.

Merge of [43439] and [43441] to the 4.9 branch.

Props kadamwhite, danielbachhuber, birgire, TimothyBlynJacobs, pento.
Fixes #44321.


Built from https://develop.svn.wordpress.org/branches/4.9@43442


git-svn-id: http://core.svn.wordpress.org/branches/4.9@43269 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 .../endpoints/class-wp-rest-posts-controller.php | 16 +++++++++++++++-
 wp-includes/version.php                          |  2 +-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
index 334d1a2db6..e93ccfbb4a 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
@@ -1667,9 +1667,23 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 		}
 
 		if ( in_array( $post->post_type, array( 'post', 'page' ), true ) || post_type_supports( $post->post_type, 'revisions' ) ) {
+			$revisions       = wp_get_post_revisions( $post->ID, array( 'fields' => 'ids' ) );
+			$revisions_count = count( $revisions );
+
 			$links['version-history'] = array(
-				'href' => rest_url( trailingslashit( $base ) . $post->ID . '/revisions' ),
+				'href'  => rest_url( trailingslashit( $base ) . $post->ID . '/revisions' ),
+				'count' => $revisions_count,
 			);
+
+			if ( $revisions_count > 0 ) {
+				$last_revision = array_shift( $revisions );
+
+				$links['predecessor-version'] = array(
+					'href' => rest_url( trailingslashit( $base ) . $post->ID . '/revisions/' . $last_revision ),
+					'id'   => $last_revision,
+				);
+			}
+
 		}
 
 		$post_type_obj = get_post_type_object( $post->post_type );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index c994f34b7d..ad72c1e2a9 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.8-alpha-43438';
+$wp_version = '4.9.8-alpha-43442';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.