Fix the related products block result when used along a grouped product (https://github.com/woocommerce/woocommerce-blocks/pull/8656)

* fix: related products and grouped products result woocommerce/woocommerce-blocks#8589

* fix crash

plugins/woocommerce-blocks/assets/js/blocks/product-query/variations/related-products.tsx

@@ -48,6 +48,13 @@ export const BLOCK_ATTRIBUTES = {
 };
 
 export const INNER_BLOCKS_TEMPLATE: InnerBlockTemplate[] = [
+	[
+		'core/heading',
+		{
+			level: 2,
+			content: __( 'Related products.', 'woo-gutenberg-products-block' ),
+		},
+	],
 	[
 		'core/post-template',
 		{ __woocommerceNamespace: PRODUCT_TEMPLATE_ID },

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

@@ -34,6 +34,14 @@ class RelatedProducts extends AbstractBlock {
 			10,
 			2
 		);
+
+		add_filter(
+			'render_block',
+			array( $this, 'render_block' ),
+			10,
+			2
+		);
+
 	}
 
 	/**
@@ -75,16 +83,82 @@ class RelatedProducts extends AbstractBlock {
 	 */
 	public function build_query( $query ) {
 		$parsed_block = $this->parsed_block;
-		if ( ! ProductQuery::is_woocommerce_variation( $parsed_block ) && 'woocommerce/related-products' !== $parsed_block['attrs']['namespace'] ) {
+		if ( ! $this->is_related_products_block( $parsed_block ) ) {
 			return $query;
 		}
-		$product          = wc_get_product();
+
-		$related_products = wc_get_related_products( $product->get_id() );
+		$related_products_ids = $this->get_related_products_ids();
+		if ( count( $related_products_ids ) < 1 ) {
+			return array();
+		}
 
 		return array(
 			'post_type'   => 'product',
-			'post__in'    => $related_products,
+			'post__in'    => $related_products_ids,
 			'post_status' => 'publish',
 		);
 	}
+
+	/**
+	 * If there are no related products, return an empty string.
+	 *
+	 * @param string $content The block content.
+	 * @param array  $block The block.
+	 *
+	 * @return string The block content.
+	 */
+	public function render_block( string $content, array $block ) {
+		if ( ! $this->is_related_products_block( $block ) ) {
+			return $content;
+		}
+
+		$related_products_ids = $this->get_related_products_ids();
+
+		if ( count( $related_products_ids ) < 1 ) {
+			return '';
+		}
+		return $content;
+	}
+
+
+
+	/**
+	 * Determines whether the block is a related products block.
+	 *
+	 * @param array $block The block.
+	 *
+	 * @return bool Whether the block is a related products block.
+	 */
+	private function is_related_products_block( $block ) {
+		if ( ProductQuery::is_woocommerce_variation( $block ) && isset( $block['attrs']['namespace'] ) && 'woocommerce/related-products' === $block['attrs']['namespace'] ) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Get related products ids.
+	 * The logic is copied from the core function woocommerce_related_products. https://github.com/woocommerce/woocommerce/blob/ca49caabcba84ce9f60a03c6d3534ec14b350b80/plugins/woocommerce/includes/wc-template-functions.php/#L2039-L2074
+	 *
+	 * @return array Products ids.
+	 */
+	private function get_related_products_ids() {
+		global $post;
+
+		$product = wc_get_product( $post->ID );
+
+		$related_products = array_filter( array_map( 'wc_get_product', wc_get_related_products( $product->get_id(), 5, $product->get_upsell_ids() ) ), 'wc_products_array_filter_visible' );
+		$related_products = wc_products_array_orderby( $related_products, 'rand', 'desc' );
+
+		$related_product_ids = array_map(
+			function( $product ) {
+				return $product->get_id();
+			},
+			$related_products
+		);
+
+		return $related_product_ids;
+	}
+
 }