Extract meta custom sources to a separate file

gutenberg.php

@@ -80,12 +80,12 @@ function gutenberg_pre_init() {
  * @param string $block_instance The block instance.
  */
 function render_custom_sources( $block_content, $block, $block_instance ) {
-	$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
+	$meta_custom_source = require __DIR__ . '/lib/custom-sources/meta.php';
+	$block_type         = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
 	if ( null === $block_type ) {
 		return $block_content;
 	}
 
-
 	$custom_sources = _wp_array_get( $block_type->supports, 'customSources', false );
 	if ( ! $custom_sources ) {
 		// TODO: for some reason the "customSources" support is not being registered as it should.
@@ -95,31 +95,10 @@ function render_custom_sources( $block_content, $block, $block_instance ) {
 	$attribute_sources = _wp_array_get( $block['attrs'], array( 'source' ), array() );
 	foreach ( $attribute_sources as $attribute_name => $attribute_source ) {
 		$attribute_config = _wp_array_get( $block_type->attributes, array( $attribute_name ), false );
-		if ( ! $attribute_config || ! $attribute_source || 'meta' !== $attribute_source['type'] ) {
-			continue;
-		}
-		$meta_field = $attribute_source['name'];
-		$meta_value = get_post_meta( $block_instance->context['postId'], $meta_field, true );
-		$p          = new WP_HTML_Tag_Processor( $block_content );
-		$found      = $p->next_tag(
-			array(
-				// TODO: build the query from CSS selector.
-				'tag_name' => $attribute_config['selector'],
-			)
-		);
-		if ( ! $found ) {
+		if ( ! $attribute_config || ! $attribute_source || $meta_custom_source['name'] !== $attribute_source['type'] ) {
 			continue;
 		}
-		$tag_name = $p->get_tag();
-		$markup   = "<$tag_name>$meta_value</$tag_name>";
-		$p2       = new WP_HTML_Tag_Processor( $markup );
-		$p2->next_tag();
-		$names = $p->get_attribute_names_with_prefix( '' );
-		foreach ( $names as $name ) {
-			$p2->set_attribute( $name, $p->get_attribute( $name ) );
-		}
-
-		$block_content = $p2 . '';
+		$block_content = $meta_custom_source['apply_source']( $block_type, $block_content, $block_instance, $attribute_source, $attribute_config );
 	}
 
 	return $block_content;

lib/custom-sources/meta.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * Meta Custom Source
+ *
+ * @package gutenberg
+ */
+
+return array(
+	'name'         => 'meta',
+	'apply_source' => function ( $block_type, $block_content, $block_instance, $attribute_source, $attribute_config ) {
+		$meta_field = $attribute_source['name'];
+		$meta_value = get_post_meta( $block_instance->context['postId'], $meta_field, true );
+		$p          = new WP_HTML_Tag_Processor( $block_content );
+		$found      = $p->next_tag(
+			array(
+				// TODO: build the query from CSS selector.
+				'tag_name' => $attribute_config['selector'],
+			)
+		);
+		if ( ! $found ) {
+			return $block_content;
+		}
+		$tag_name = $p->get_tag();
+		$markup   = "<$tag_name>$meta_value</$tag_name>";
+		$p2       = new WP_HTML_Tag_Processor( $markup );
+		$p2->next_tag();
+		$names = $p->get_attribute_names_with_prefix( '' );
+		foreach ( $names as $name ) {
+			$p2->set_attribute( $name, $p->get_attribute( $name ) );
+		}
+
+		return $p2 . '';
+	},
+);

packages/editor/src/attributes-custom-sources/meta.js

@@ -0,0 +1,110 @@
+/**
+ * WordPress dependencies
+ */
+import { getBlockType } from '@wordpress/blocks';
+import { useEntityProp } from '@wordpress/core-data';
+import { useMemo, useCallback } from '@wordpress/element';
+
+export default {
+	name: 'meta',
+
+	useSource( {
+		name,
+		context: { postType, postId },
+		attributes,
+		setAttributes,
+	} ) {
+		const [ meta, setMeta ] = useEntityProp(
+			'postType',
+			postType,
+			'meta',
+			postId
+		);
+
+		const blockType = getBlockType( name );
+
+		const attributesWithSourcedAttributes = useMemo( () => {
+			if ( ! blockType.supports?.customSources ) {
+				return attributes;
+			}
+			return {
+				...attributes,
+				...Object.fromEntries(
+					Object.keys( blockType.supports.customSources ).map(
+						( attributeName ) => {
+							if (
+								attributes.source?.[ attributeName ]?.type ===
+								'meta'
+							) {
+								return [
+									attributeName,
+									meta?.[
+										attributes.source?.[ attributeName ]
+											?.name
+									],
+								];
+							}
+							return [
+								attributeName,
+								attributes[ attributeName ],
+							];
+						}
+					)
+				),
+			};
+		}, [ blockType.supports?.customSources, attributes, meta ] );
+
+		const updatedSetAttributes = useCallback(
+			( nextAttributes ) => {
+				const nextMeta = Object.fromEntries(
+					Object.entries( nextAttributes ?? {} )
+						.filter(
+							// Filter to intersection of keys between the updated
+							// attributes and those with an associated meta key.
+							( [ key ] ) =>
+								blockType.supports?.customSources &&
+								key in blockType.supports?.customSources &&
+								attributes.source?.[ key ]?.type === 'meta'
+						)
+						.map( ( [ attributeKey, value ] ) => [
+							// Rename the keys to the expected meta key name.
+							attributes.source?.[ attributeKey ]?.name,
+							value,
+						] )
+				);
+
+				const updatedAttributes = Object.entries( nextMeta ).length
+					? Object.fromEntries(
+							Object.entries( nextAttributes ).filter(
+								( [ key ] ) =>
+									! (
+										blockType.supports?.customSources &&
+										key in
+											blockType.supports?.customSources &&
+										attributes.source?.[ key ]?.type ===
+											'meta'
+									)
+							)
+					  )
+					: nextAttributes;
+
+				if ( Object.entries( nextMeta ).length ) {
+					setMeta( nextMeta );
+				}
+
+				setAttributes( updatedAttributes );
+			},
+			[
+				setAttributes,
+				attributes.source,
+				blockType.supports?.customSources,
+				setMeta,
+			]
+		);
+
+		return {
+			setAttributes: updatedSetAttributes,
+			attributes: attributesWithSourcedAttributes,
+		};
+	},
+};