Post Settings: Refactor revisions handling to avoid performance issues

editor/selectors.js

@@ -269,6 +269,27 @@ export function getCurrentPostId( state ) {
 	return getCurrentPost( state ).id || null;
 }
 
+/**
+ * Returns the number of revisions of the post currently being edited.
+ *
+ * @param  {Object}  state Global application state
+ * @return {Number}        Number of revisions
+ */
+export function getCurrentPostRevisionsCount( state ) {
+	return get( getCurrentPost( state ), 'revisions.count', 0 );
+}
+
+/**
+ * Returns the last revision ID of the post currently being edited,
+ * or null if the post has no revisions.
+ *
+ * @param  {Object}  state Global application state
+ * @return {?Number}       ID of the last revision
+ */
+export function getCurrentPostLastRevisionId( state ) {
+	return get( getCurrentPost( state ), 'revisions.last_id', null );
+}
+
 /**
  * Returns any post values which have been changed in the editor but not yet
  * been saved.

editor/sidebar/last-revision/index.js

@@ -2,65 +2,51 @@
  * External dependencies
  */
 import { connect } from 'react-redux';
-import { flowRight, first } from 'lodash';
 
 /**
  * WordPress dependencies
  */
 import { sprintf, _n } from '@wordpress/i18n';
-import { IconButton, PanelBody, withAPIData } from '@wordpress/components';
+import { IconButton, PanelBody } from '@wordpress/components';
 
 /**
  * Internal dependencies
  */
 import './style.scss';
 import {
-	isEditedPostNew,
-	getCurrentPostId,
-	getCurrentPostType,
-	isSavingPost,
+	getCurrentPostLastRevisionId,
+	getCurrentPostRevisionsCount,
 } from '../../selectors';
 import { getWPAdminURL } from '../../utils/url';
 
-function LastRevision( { revisions } ) {
-	const lastRevision = first( revisions.data );
-	if ( ! lastRevision ) {
+function LastRevision( { lastRevisionId, revisionsCount } ) {
+	if ( ! lastRevisionId ) {
 		return null;
 	}
 
 	return (
 		<PanelBody>
 			<IconButton
-				href={ getWPAdminURL( 'revision.php', { revision: lastRevision.id } ) }
+				href={ getWPAdminURL( 'revision.php', { revision: lastRevisionId } ) }
 				className="editor-last-revision__title"
 				icon="backup"
 			>
 				{
 					sprintf(
-						_n( '%d Revision', '%d Revisions', revisions.data.length ),
-						revisions.data.length
+						_n( '%d Revision', '%d Revisions', revisionsCount ),
+						revisionsCount
 					)
 				}
 			</IconButton>
 		</PanelBody>
 	);
 }
 
-export default flowRight(
-	connect(
-		( state ) => {
-			return {
-				isNew: isEditedPostNew( state ),
-				postId: getCurrentPostId( state ),
-				postType: getCurrentPostType( state ),
-				isSaving: isSavingPost( state ),
-			};
-		}
-	),
-	withAPIData( ( props, { type } ) => {
-		const { postType, postId } = props;
+export default connect(
+	( state ) => {
 		return {
-			revisions: `/wp/v2/${ type( postType ) }/${ postId }/revisions`,
+			lastRevisionId: getCurrentPostLastRevisionId( state ),
+			revisionsCount: getCurrentPostRevisionsCount( state ),
 		};
-	} )
+	}
 )( LastRevision );

editor/test/selectors.js

@@ -24,6 +24,8 @@ import {
 	isCleanNewPost,
 	getCurrentPost,
 	getCurrentPostId,
+	getCurrentPostLastRevisionId,
+	getCurrentPostRevisionsCount,
 	getCurrentPostType,
 	getPostEdits,
 	getEditedPostTitle,
@@ -875,6 +877,50 @@ describe( 'selectors', () => {
 		} );
 	} );
 
+	describe( 'getCurrentPostLastRevisionId', () => {
+		it( 'should return null if the post has not yet been saved', () => {
+			const state = {
+				currentPost: {},
+			};
+
+			expect( getCurrentPostLastRevisionId( state ) ).toBeNull();
+		} );
+
+		it( 'should return the last revision ID', () => {
+			const state = {
+				currentPost: {
+					revisions: {
+						last_id: 123,
+					},
+				},
+			};
+
+			expect( getCurrentPostLastRevisionId( state ) ).toBe( 123 );
+		} );
+	} );
+
+	describe( 'getCurrentPostRevisionsCount', () => {
+		it( 'should return 0 if the post has no revisions', () => {
+			const state = {
+				currentPost: {},
+			};
+
+			expect( getCurrentPostRevisionsCount( state ) ).toBe( 0 );
+		} );
+
+		it( 'should return the number of revisions', () => {
+			const state = {
+				currentPost: {
+					revisions: {
+						count: 5,
+					},
+				},
+			};
+
+			expect( getCurrentPostRevisionsCount( state ) ).toBe( 5 );
+		} );
+	} );
+
 	describe( 'getCurrentPostType', () => {
 		it( 'should return the post type', () => {
 			const state = {

lib/client-assets.php

@@ -462,12 +462,6 @@ function gutenberg_extend_wp_api_backbone_client() {
 				return model.prototype.route && route === model.prototype.route.index;
 			} );
 		};
-		wp.api.getPostTypeRevisionsCollection = function( postType ) {
-			var route = '/' + wpApiSettings.versionString + this.postTypeRestBaseMapping[ postType ] + '/(?P<parent>[\\\\d]+)/revisions';
-			return _.find( wp.api.collections, function( model ) {
-				return model.prototype.route && route === model.prototype.route.index;
-			} );
-		};
 		wp.api.getTaxonomyModel = function( taxonomy ) {
 			var route = '/' + wpApiSettings.versionString + this.taxonomyRestBaseMapping[ taxonomy ] + '/(?P<id>[\\\\d]+)';
 			return _.find( wp.api.models, function( model ) {
@@ -703,10 +697,6 @@ function gutenberg_editor_scripts_and_styles( $hook ) {
 		gutenberg_get_rest_link( $post_to_edit, 'about', 'edit' ),
 	);
 
-	if ( ! $is_new_post ) {
-		$preload_paths[] = gutenberg_get_rest_link( $post_to_edit, 'version-history' );
-	}
-
 	$preload_data = array_reduce(
 		$preload_paths,
 		'gutenberg_preload_api_request',

lib/register.php

@@ -360,6 +360,46 @@ function gutenberg_register_rest_routes() {
 add_action( 'rest_api_init', 'gutenberg_register_rest_routes' );
 
 
+/**
+ * Gets revisions details for the selected post.
+ *
+ * @since 1.6.0
+ *
+ * @param array $post The post object from the response.
+ * @return array|null Revisions details or null when no revisions present.
+ */
+function gutenberg_get_post_revisions( $post ) {
+	$revisions       = wp_get_post_revisions( $post['id'] );
+	$revisions_count = count( $revisions );
+	if ( 0 === $revisions_count ) {
+		return null;
+	}
+
+	$last_revision = array_shift( $revisions );
+
+	return array(
+		'count'   => $revisions_count,
+		'last_id' => $last_revision->ID,
+	);
+}
+
+/**
+ * Adds the custom field `revisions` to the REST API response of post.
+ *
+ * TODO: This is a temporary solution. Next step would be to find a solution that is limited to the editor.
+ *
+ * @since 1.6.0
+ */
+function gutenberg_register_rest_api_post_revisions() {
+	register_rest_field( get_post_types( '', 'names' ),
+		'revisions',
+		array(
+			'get_callback' => 'gutenberg_get_post_revisions',
+		)
+	);
+}
+add_action( 'rest_api_init', 'gutenberg_register_rest_api_post_revisions' );
+
 /**
  * Injects a hidden input in the edit form to propagate the information that classic editor is selected.
  *