Introduce theme_supports with formats to REST API index

core-data/actions.js

@@ -64,3 +64,17 @@ export function receivePostTypes( postTypes ) {
 		postTypes: castArray( postTypes ),
 	};
 }
+
+/**
+ * Returns an action object used in signalling that the index has been received.
+ *
+ * @param {Object} index Index received.
+ *
+ * @return {Object} Action object.
+ */
+export function receiveIndex( index ) {
+	return {
+		type: 'RECEIVE_INDEX',
+		index: index,
+	};
+}

core-data/reducer.js

@@ -82,8 +82,29 @@ export function postTypes( state = {}, action ) {
 	return state;
 }
 
+/**
+ * Reducer managing indexes data.
+ *
+ * @param {Object} state  Current state.
+ * @param {Object} action Dispatched action.
+ *
+ * @return {Object} Updated state.
+ */
+export function indexData( state = {}, action ) {
+	switch ( action.type ) {
+		case 'RECEIVE_INDEX':
+			return {
+				...state,
+				...action.index,
+			};
+	}
+
+	return state;
+}
+
 export default combineReducers( {
 	terms,
 	media,
 	postTypes,
+	indexData,
 } );

core-data/resolvers.js

@@ -11,6 +11,7 @@ import {
 	receiveTerms,
 	receiveMedia,
 	receivePostTypes,
+	receiveIndex,
 } from './actions';
 
 /**
@@ -44,3 +45,11 @@ export async function* getPostType( state, slug ) {
 	const postType = await apiRequest( { path: `/wp/v2/types/${ slug }?context=edit` } );
 	yield receivePostTypes( postType );
 }
+
+/**
+ * Requests theme supports data from the index.
+ */
+export async function* getThemeSupports() {
+	const index = await apiRequest( { path: '/' } );
+	yield receiveIndex( index );
+}

core-data/selectors.js

@@ -69,3 +69,14 @@ export function getMedia( state, id ) {
 export function getPostType( state, slug ) {
 	return state.postTypes[ slug ];
 }
+
+/**
+ * Return theme suports data in the index.
+ *
+ * @param {Object} state    Data state.
+ *
+ * @return {Mixed?}     Index data.
+ */
+export function getThemeSupports( state ) {
+	return state.indexData.theme_supports;
+}

editor/components/post-format/index.js

@@ -1,7 +1,7 @@
 /**
  * External dependencies
  */
-import { find, get } from 'lodash';
+import { find, get, union } from 'lodash';
 
 /**
  * WordPress dependencies
@@ -71,11 +71,14 @@ function PostFormat( { onUpdatePostFormat, postFormat = 'standard', supportedFor
 export default compose( [
 	withSelect( ( select ) => {
 		const { getEditedPostAttribute, getSuggestedPostFormat } = select( 'core/editor' );
-		const { getPostType } = select( 'core' );
-		const postType = getPostType( getEditedPostAttribute( 'type' ) );
+		const format = getEditedPostAttribute( 'format' );
+		const themeSupports = select( 'core' ).getThemeSupports();
+		// Ensure current format is always in the set.
+		// The current format may not be a format supported by the theme.
+		const supportedFormats = union( [ format ], get( themeSupports, 'formats', [] ) );
 		return {
 			postFormat: getEditedPostAttribute( 'format' ),
-			supportedFormats: get( postType, [ 'formats' ], [] ),
+			supportedFormats,
 			suggestedFormat: getSuggestedPostFormat(),
 		};
 	} ),

lib/compat.php

@@ -238,6 +238,30 @@ function gutenberg_ensure_wp_json_has_permalink_structure( $response ) {
 }
 add_filter( 'rest_index', 'gutenberg_ensure_wp_json_has_permalink_structure' );
 
+/**
+ * Ensure that the wp-json index contains the 'theme-supports' setting as
+ * part of its site info elements.
+ *
+ * @param WP_REST_Response $response WP REST API response of the wp-json index.
+ * @return WP_REST_Response Response that contains theme-supports.
+ */
+function gutenberg_ensure_wp_json_has_theme_supports( $response ) {
+	$site_info = $response->get_data();
+	if ( ! array_key_exists( 'theme_supports', $site_info ) ) {
+		$site_info['theme_supports'] = array();
+	}
+	if ( ! array_key_exists( 'formats', $site_info['theme_supports'] ) ) {
+		$formats = get_theme_support( 'post-formats' );
+		$formats = is_array( $formats ) ? array_values( $formats[0] ) : array();
+		$formats = array_merge( array( 'standard' ), $formats );
+
+		$site_info['theme_supports']['formats'] = $formats;
+	}
+	$response->set_data( $site_info );
+	return $response;
+}
+add_filter( 'rest_index', 'gutenberg_ensure_wp_json_has_theme_supports' );
+
 /**
  * As a substitute for the default content `wpautop` filter, applies autop
  * behavior only for posts where content does not contain blocks.
@@ -490,26 +514,6 @@ function gutenberg_get_post_type_viewable( $post_type ) {
 	return is_post_type_viewable( $post_type['slug'] );
 }
 
-/**
- * Includes the value for the 'formats' attribute of a post type resource.
- *
- * @see https://core.trac.wordpress.org/ticket/43817
- *
- * @param object $post_type Post type response object.
- * @return array The list of post formats that the post type supports.
- */
-function gutenberg_get_post_type_formats( $post_type ) {
-	if ( ! post_type_supports( $post_type['slug'], 'post-formats' ) ) {
-		return array();
-	}
-
-	$formats = get_theme_support( 'post-formats' );
-	$formats = is_array( $formats ) ? array_values( $formats[0] ) : array();
-	$formats = array_merge( array( 'standard' ), $formats );
-
-	return $formats;
-}
-
 /**
  * Adds extra fields to the REST API post type response.
  *
@@ -530,17 +534,5 @@ function gutenberg_register_rest_api_post_type_fields() {
 		)
 	);
 
-	register_rest_field( 'type',
-		'formats',
-		array(
-			'get_callback' => 'gutenberg_get_post_type_formats',
-			'schema'       => array(
-				'description' => __( 'The list of post formats that this post type supports', 'gutenberg' ),
-				'type'        => 'array',
-				'context'     => array( 'edit', 'view' ),
-				'readonly'    => true,
-			),
-		)
-	);
 }
 add_action( 'rest_api_init', 'gutenberg_register_rest_api_post_type_fields' );

phpunit/class-gutenberg-rest-api-test.php

@@ -119,4 +119,16 @@ function test_viewable_field_without_context() {
 		$result   = $response->get_data();
 		$this->assertFalse( isset( $result['viewable'] ) );
 	}
+
+	/**
+	 * Should include relevant data in the 'theme_supports' key of index.
+	 */
+	function test_theme_supports_index() {
+		$request  = new WP_REST_Request( 'GET', '/' );
+		$response = rest_do_request( $request );
+		$result   = $response->get_data();
+		$this->assertTrue( isset( $result['theme_supports'] ) );
+		$this->assertTrue( isset( $result['theme_supports']['formats'] ) );
+		$this->assertTrue( in_array( 'standard', $result['theme_supports']['formats'] ) );
+	}
 }