Provide product filter blocks a method to know when to display. (https://github.com/woocommerce/woocommerce-blocks/pull/6270)

* Add has_filterable_products data to the AllProducts block to be used by product filter blocks

* Add has_filterable_products data to the ClassicTemplate block to be used by product filter blocks

* Add ClassicTemplatesCompatibility class which will add necessary data to the front-end of core PHP templates of Classic Themes for filter blocks being used as widgets.

* Update comment of set_php_template_data method on ClassicTemplatesCompatibility class

* Move conditional checking if the current theme is a block theme in ClassicTemplatesCompatibility class

plugins/woocommerce-blocks/src/BlockTypes/AllProducts.php

@@ -21,6 +21,9 @@ class AllProducts extends AbstractBlock {
 	 */
 	protected function enqueue_data( array $attributes = [] ) {
 		parent::enqueue_data( $attributes );
+		// Set this so filter blocks being used as widgets know when to render.
+		$this->asset_data_registry->add( 'has_filterable_products', true, null );
+
 		$this->asset_data_registry->add( 'min_columns', wc_get_theme_support( 'product_blocks::min_columns', 1 ), true );
 		$this->asset_data_registry->add( 'max_columns', wc_get_theme_support( 'product_blocks::max_columns', 6 ), true );
 		$this->asset_data_registry->add( 'default_columns', wc_get_theme_support( 'product_blocks::default_columns', 3 ), true );

plugins/woocommerce-blocks/src/BlockTypes/ClassicTemplate.php

@@ -61,12 +61,11 @@ class ClassicTemplate extends AbstractDynamicBlock {
 		if ( 'single-product' === $attributes['template'] ) {
 			return $this->render_single_product();
 		} elseif ( in_array( $attributes['template'], $archive_templates, true ) ) {
-			// We need to set this so that our product filters can detect if it's a PHP template.
-			$this->asset_data_registry->add(
-				'is_rendering_php_template',
-				true,
-				null
-			);
+			// Set this so that our product filters can detect if it's a PHP template.
+			$this->asset_data_registry->add( 'is_rendering_php_template', true, null );
+
+			// Set this so filter blocks being used as widgets know when to render.
+			$this->asset_data_registry->add( 'has_filterable_products', true, null );
 
 			$this->asset_data_registry->add(
 				'page_url',

plugins/woocommerce-blocks/src/Domain/Bootstrap.php

@@ -13,6 +13,7 @@ use Automattic\WooCommerce\Blocks\Domain\Services\GoogleAnalytics;
 use Automattic\WooCommerce\Blocks\InboxNotifications;
 use Automattic\WooCommerce\Blocks\Installer;
 use Automattic\WooCommerce\Blocks\Templates\ProductSearchResultsTemplate;
+use Automattic\WooCommerce\Blocks\Templates\ClassicTemplatesCompatibility;
 use Automattic\WooCommerce\Blocks\Payments\Api as PaymentsApi;
 use Automattic\WooCommerce\Blocks\Payments\Integrations\BankTransfer;
 use Automattic\WooCommerce\Blocks\Payments\Integrations\CashOnDelivery;
@@ -97,6 +98,7 @@ class Bootstrap {
 		$this->container->get( BlockTypesController::class );
 		$this->container->get( BlockTemplatesController::class );
 		$this->container->get( ProductSearchResultsTemplate::class );
+		$this->container->get( ClassicTemplatesCompatibility::class );
 		if ( $this->package->feature()->is_feature_plugin_build() ) {
 			$this->container->get( PaymentsApi::class );
 		}
@@ -229,6 +231,13 @@ class Bootstrap {
 				return new ProductSearchResultsTemplate();
 			}
 		);
+		$this->container->register(
+			ClassicTemplatesCompatibility::class,
+			function ( Container $container ) {
+				$asset_data_registry = $container->get( AssetDataRegistry::class );
+				return new ClassicTemplatesCompatibility( $asset_data_registry );
+			}
+		);
 		$this->container->register(
 			DraftOrders::class,
 			function( Container $container ) {

plugins/woocommerce-blocks/src/Templates/ClassicTemplatesCompatibility.php

@@ -0,0 +1,72 @@
+<?php
+namespace Automattic\WooCommerce\Blocks\Templates;
+
+use Automattic\WooCommerce\Blocks\Assets\AssetDataRegistry;
+
+/**
+ * ClassicTemplatesCompatibility class.
+ *
+ * To bridge the gap on compatibility with widget blocks and classic PHP core templates.
+ *
+ * @internal
+ */
+class ClassicTemplatesCompatibility {
+
+	/**
+	 * Instance of the asset data registry.
+	 *
+	 * @var AssetDataRegistry
+	 */
+	protected $asset_data_registry;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param AssetDataRegistry $asset_data_registry Instance of the asset data registry.
+	 */
+	public function __construct( AssetDataRegistry $asset_data_registry ) {
+		$this->asset_data_registry = $asset_data_registry;
+		$this->init();
+	}
+
+	/**
+	 * Initialization method.
+	 */
+	protected function init() {
+		if ( ! wc_current_theme_is_fse_theme() ) {
+			add_action( 'template_redirect', array( $this, 'set_classic_template_data' ) );
+		}
+	}
+
+	/**
+	 * Executes the methods which set the necessary data needed for filter blocks to work correctly as widgets in Classic templates.
+	 *
+	 * @return void
+	 */
+	public function set_classic_template_data() {
+		$this->set_filterable_product_data();
+		$this->set_php_template_data();
+	}
+
+	/**
+	 * This method passes the value `has_filterable_products` to the front-end for product archive pages,
+	 * so that widget product filter blocks are aware of the context they are in and can render accordingly.
+	 *
+	 * @return void
+	 */
+	public function set_filterable_product_data() {
+		if ( is_shop() || is_product_taxonomy() ) {
+			$this->asset_data_registry->add( 'has_filterable_products', true, null );
+		}
+	}
+
+	/**
+	 * This method passes the value `is_rendering_php_template` to the front-end of Classic themes,
+	 * so that widget product filter blocks are aware of how to filter the products.
+	 *
+	 * @return void
+	 */
+	public function set_php_template_data() {
+		$this->asset_data_registry->add( 'is_rendering_php_template', true, null );
+	}
+}