Footnotes: fix published preview

packages/block-library/src/footnotes/index.php

@@ -212,3 +212,76 @@ function wp_get_footnotes_from_revision( $revision_field, $field, $revision ) {
 	return get_metadata( 'post', $revision->ID, $field, true );
 }
 add_filter( 'wp_post_revision_field_footnotes', 'wp_get_footnotes_from_revision', 10, 3 );
+
+/**
+ * The REST API autosave endpoint doesn't save meta, so we can use the
+ * `wp_creating_autosave` when it updates an exiting autosave, and
+ * `_wp_put_post_revision` when it creates a new autosave.
+ *
+ * @since 6.3.0
+ *
+ * @param int|array $autosave The autosave ID or array.
+ */
+function _wp_rest_api_autosave_meta( $autosave ) {
+	// Ensure it's a REST API request.
+	if ( ! defined( 'REST_REQUEST' ) || ! REST_REQUEST ) {
+		return;
+	}
+
+	$body = rest_get_server()->get_raw_data();
+	$body = json_decode( $body, true );
+
+	if ( ! isset( $body['meta']['footnotes'] ) ) {
+		return;
+	}
+
+	// `wp_creating_autosave` passes the array,
+	// `_wp_put_post_revision` passes the ID.
+	$id = is_int( $autosave ) ? $autosave : $autosave['ID'];
+
+	if ( ! $id ) {
+		return;
+	}
+
+	update_post_meta( $id, 'footnotes', $body['meta']['footnotes'] );
+}
+// See https://github.com/WordPress/wordpress-develop/blob/2103cb9966e57d452c94218bbc3171579b536a40/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php#L391C1-L391C1.
+add_action( 'wp_creating_autosave', '_wp_rest_api_autosave_meta' );
+// See https://github.com/WordPress/wordpress-develop/blob/2103cb9966e57d452c94218bbc3171579b536a40/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php#L398.
+// Then https://github.com/WordPress/wordpress-develop/blob/2103cb9966e57d452c94218bbc3171579b536a40/src/wp-includes/revision.php#L367.
+add_action( '_wp_put_post_revision', '_wp_rest_api_autosave_meta' );
+
+/**
+ * This is a workaround for the autosave endpoint returning early if the
+ * revision field are equal. The problem is that "footnotes" is not real
+ * revision post field, so there's nothing to compare against.
+ *
+ * This trick sets the "footnotes" field (value doesn't matter), which will
+ * cause the autosave endpoint to always update the latest revision. That should
+ * be fine, it should be ok to update the revision even if nothing changed. Of
+ * course, this is temporary fix.
+ *
+ * @since 6.3.0
+ *
+ * @param WP_Post         $prepared_post The prepared post object.
+ * @param WP_REST_Request $request       The request object.
+ *
+ * See https://github.com/WordPress/wordpress-develop/blob/2103cb9966e57d452c94218bbc3171579b536a40/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php#L365-L384.
+ * See https://github.com/WordPress/wordpress-develop/blob/2103cb9966e57d452c94218bbc3171579b536a40/src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php#L219.
+ */
+function _wp_rest_api_force_autosave_difference( $prepared_post, $request ) {
+	// We only want to be altering POST requests.
+	if ( $request->get_method() !== 'POST' ) {
+		return $prepared_post;
+	}
+
+	// Only alter requests for the '/autosaves' route.
+	if ( substr( $request->get_route(), -strlen( '/autosaves' ) ) !== '/autosaves' ) {
+		return $prepared_post;
+	}
+
+	$prepared_post->footnotes = '[]';
+	return $prepared_post;
+}
+
+add_filter( 'rest_pre_insert_post', '_wp_rest_api_force_autosave_difference', 10, 2 );

packages/core-data/src/actions.js

@@ -551,9 +551,12 @@ export const saveEntityRecord =
 					data = Object.keys( data ).reduce(
 						( acc, key ) => {
 							if (
-								[ 'title', 'excerpt', 'content' ].includes(
-									key
-								)
+								[
+									'title',
+									'excerpt',
+									'content',
+									'meta',
+								].includes( key )
 							) {
 								acc[ key ] = data[ key ];
 							}

packages/editor/src/store/selectors.js

@@ -611,8 +611,8 @@ export const isEditedPostAutosaveable = createRegistrySelector(
 			return true;
 		}
 
-		// If the title or excerpt has changed, the post is autosaveable.
-		return [ 'title', 'excerpt' ].some(
+		// If title, excerpt, or meta have changed, the post is autosaveable.
+		return [ 'title', 'excerpt', 'meta' ].some(
 			( field ) =>
 				getPostRawValue( autosave[ field ] ) !==
 				getEditedPostAttribute( state, field )

test/e2e/specs/editor/various/footnotes.spec.js

@@ -360,4 +360,44 @@ test.describe( 'Footnotes', () => {
 			},
 		] );
 	} );
+
+	test( 'can be previewed when published', async ( { editor, page } ) => {
+		await editor.canvas.click( 'role=button[name="Add default block"i]' );
+		await page.keyboard.type( 'a' );
+
+		await editor.showBlockToolbar();
+		await editor.clickBlockToolbarButton( 'More' );
+		await page.locator( 'button:text("Footnote")' ).click();
+
+		await page.keyboard.type( '1' );
+
+		// Publish post.
+		await editor.publishPost();
+
+		await editor.canvas.click( 'ol.wp-block-footnotes li span' );
+		await page.keyboard.press( 'End' );
+		await page.keyboard.type( '2' );
+
+		const editorPage = page;
+		const previewPage = await editor.openPreviewPage();
+
+		await expect(
+			previewPage.locator( 'ol.wp-block-footnotes li' )
+		).toHaveText( '12 ↩︎' );
+
+		await previewPage.close();
+		await editorPage.bringToFront();
+
+		// Test again, this time with an existing revision (different code
+		// path).
+		await editor.canvas.click( 'ol.wp-block-footnotes li span' );
+		await page.keyboard.press( 'End' );
+		await page.keyboard.type( '3' );
+
+		const previewPage2 = await editor.openPreviewPage();
+
+		await expect(
+			previewPage2.locator( 'ol.wp-block-footnotes li' )
+		).toHaveText( '123  ↩︎' );
+	} );
 } );