Lazy load varients

src/wp-admin/includes/post.php

@@ -2302,7 +2302,6 @@
 		'ancestor'         => 'ancestor',
 		'keywords'         => 'keywords',
 		'example'          => 'example',
-		'variations'       => 'variations',
 	);
 
 	foreach ( $block_registry->get_all_registered() as $block_name => $block_type ) {
@@ -2317,6 +2316,7 @@
 
 			$blocks[ $block_name ][ $key ] = $block_type->{ $field };
 		}
+		$blocks[ $block_name ][ 'variations' ] = $block_type->get_variations();
 	}
 
 	return $blocks;

src/wp-includes/blocks/navigation-link.php

@@ -323,12 +323,11 @@ function build_variation_for_navigation_link( $entity, $kind ) {
 }
 
 /**
- * Register the navigation link block.
+ * Returns an array of variations for the navigation link block.
  *
- * @uses render_block_core_navigation()
- * @throws WP_Error An WP_Error exception parsing the block definition.
+ * @return array
  */
-function register_block_core_navigation_link() {
+function build_navigation_link_block_variations() {
 	$post_types = get_post_types( array( 'show_in_nav_menus' => true ), 'objects' );
 	$taxonomies = get_taxonomies( array( 'show_in_nav_menus' => true ), 'objects' );
 
@@ -360,11 +359,21 @@ function register_block_core_navigation_link() {
 		}
 	}
 
+	return array_merge( $built_ins, $variations );
+}
+
+/**
+ * Register the navigation link block.
+ *
+ * @uses render_block_core_navigation()
+ * @throws WP_Error An WP_Error exception parsing the block definition.
+ */
+function register_block_core_navigation_link() {
 	register_block_type_from_metadata(
 		__DIR__ . '/navigation-link',
 		array(
-			'render_callback' => 'render_block_core_navigation_link',
-			'variations'      => array_merge( $built_ins, $variations ),
+			'render_callback'    => 'render_block_core_navigation_link',
+			'variation_callback' => 'build_navigation_link_block_variations',
 		)
 	);
 }

src/wp-includes/blocks/post-terms.php

@@ -59,9 +59,9 @@ function render_block_core_post_terms( $attributes, $content, $block ) {
 }
 
 /**
- * Registers the `core/post-terms` block on the server.
+ * @return array
  */
-function register_block_core_post_terms() {
+function build_post_term_block_variations() {
 	$taxonomies = get_taxonomies(
 		array(
 			'publicly_queryable' => true,
@@ -82,7 +82,7 @@ function register_block_core_post_terms() {
 			'name'        => $taxonomy->name,
 			'title'       => $taxonomy->label,
 			'description' => sprintf(
-				/* translators: %s: taxonomy's label */
+			/* translators: %s: taxonomy's label */
 				__( 'Display a list of assigned terms from the taxonomy: %s' ),
 				$taxonomy->label
 			),
@@ -102,12 +102,18 @@ function register_block_core_post_terms() {
 			$custom_variations[] = $variation;
 		}
 	}
+	return array_merge( $built_ins, $custom_variations );
+}
 
+/**
+ * Registers the `core/post-terms` block on the server.
+ */
+function register_block_core_post_terms() {
 	register_block_type_from_metadata(
 		__DIR__ . '/post-terms',
 		array(
-			'render_callback' => 'render_block_core_post_terms',
-			'variations'      => array_merge( $built_ins, $custom_variations ),
+			'render_callback'    => 'render_block_core_post_terms',
+			'variation_callback' => 'build_post_term_block_variations',
 		)
 	);
 }

src/wp-includes/blocks/template-part.php

@@ -275,8 +275,8 @@ function register_block_core_template_part() {
 	register_block_type_from_metadata(
 		__DIR__ . '/template-part',
 		array(
-			'render_callback' => 'render_block_core_template_part',
-			'variations'      => build_template_part_block_variations(),
+			'render_callback'    => 'render_block_core_template_part',
+			'variation_callback' => 'build_template_part_block_variations',
 		)
 	);
 }

src/wp-includes/class-wp-block-type.php

@@ -115,7 +115,15 @@ class WP_Block_Type {
 	 * @since 5.8.0
 	 * @var array[]
 	 */
-	public $variations = array();
+	protected $variations = array();
+
+	/**
+	 * Block variations callback.
+	 *
+	 * @since 6.5.0
+	 * @var callable[]
+	 */
+	public $variation_callback;
 
 	/**
 	 * Custom CSS selectors for theme.json style generation.
@@ -292,6 +300,7 @@ class WP_Block_Type {
 	 *     @type string|null   $textdomain               The translation textdomain.
 	 *     @type array[]       $styles                   Alternative block styles.
 	 *     @type array[]       $variations               Block variations.
+	 *     @type callable      $variation_callback       Block variations callback.
 	 *     @type array         $selectors                Custom CSS selectors for theme.json style generation.
 	 *     @type array|null    $supports                 Supported features.
 	 *     @type array|null    $example                  Structured data for the block preview.
@@ -325,6 +334,11 @@ public function __construct( $block_type, $args = array() ) {
 	 *                                   null when value not found, or void when unknown property name provided.
 	 */
 	public function __get( $name ) {
+		if ( 'variations' === $name ) {
+			_doing_it_wrong( __CLASS__, __( 'Calling the variation property is not recommended, call get_variations instead.' ), '6.5.0' );
+			return $this->get_variations();
+		}
+
 		if ( ! in_array( $name, $this->deprecated_properties, true ) ) {
 			return;
 		}
@@ -353,6 +367,10 @@ public function __get( $name ) {
 	 *              or false otherwise.
 	 */
 	public function __isset( $name ) {
+		if ( 'variations' === $name && isset( $this->variation_callback ) ) {
+			return true;
+		}
+
 		if ( ! in_array( $name, $this->deprecated_properties, true ) ) {
 			return false;
 		}
@@ -540,4 +558,19 @@ public function get_attributes() {
 			$this->attributes :
 			array();
 	}
+
+	/**
+	 * Get block variations.
+	 *
+	 * @since 6.5.0
+	 *
+	 * @return array[]
+	 */
+	public function get_variations() {
+		if ( isset( $this->variation_callback ) && is_callable( $this->variation_callback ) ) {
+			return call_user_func( $this->variation_callback );
+		}
+
+		return $this->variations;
+	}
 }

src/wp-includes/rest-api/endpoints/class-wp-rest-block-types-controller.php

@@ -292,7 +292,6 @@ public function prepare_item_for_response( $item, $request ) {
 				'view_script_handles',
 				'editor_style_handles',
 				'style_handles',
-				'variations',
 				'block_hooks',
 			),
 			$deprecated_fields
@@ -314,6 +313,10 @@ public function prepare_item_for_response( $item, $request ) {
 			}
 		}
 
+		if ( rest_is_field_included( 'variations', $fields ) ) {
+			$data['variations'] = $block_type->get_variations();
+		}
+
 		if ( rest_is_field_included( 'styles', $fields ) ) {
 			$styles         = $this->style_registry->get_registered_styles_for_block( $block_type->name );
 			$styles         = array_values( $styles );