Store API: Add support to query product_variations by attributes (#42983

)

Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Paulo Arromba <17236129+wavvves@users.noreply.github.com>

plugins/woocommerce/changelog/42983-update-store-api-product-variation-attributes-support

@@ -0,0 +1,4 @@
+Significance: minor
+Type: fix
+
+Store API: Add support to query `product_variations` by attribute slugs.

plugins/woocommerce/src/StoreApi/Utilities/ProductQuery.php

@@ -159,12 +159,19 @@ function ( $value ) {
 		}
 
 		// Build tax_query if taxonomies are set.
-		if ( ! empty( $tax_query ) ) {
+		if ( ! empty( $tax_query ) && 'product_variation' !== $args['post_type'] ) {
 			if ( ! empty( $args['tax_query'] ) ) {
 				$args['tax_query'] = array_merge( $tax_query, $args['tax_query'] ); // phpcs:ignore
 			} else {
 				$args['tax_query'] = $tax_query; // phpcs:ignore
 			}
+		} else {
+			// For product_variantions we need to convert the tax_query to a meta_query.
+			if ( ! empty( $args['tax_query'] ) ) {
+				$args['meta_query'] = $this->convert_tax_query_to_meta_query( array_merge( $tax_query, $args['tax_query'] ) ); // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_query
+			} else {
+				$args['meta_query'] = $this->convert_tax_query_to_meta_query( $tax_query ); // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_query
+			}
 		}
 
 		// Filter featured.
@@ -239,6 +246,34 @@ function ( $value ) {
 		return $args;
 	}
 
+	/**
+	 * Convert the tax_query to a meta_query which is needed to support filtering by attributes for variations.
+	 *
+	 * @param array $tax_query The tax_query to convert.
+	 * @return array
+	 */
+	public function convert_tax_query_to_meta_query( $tax_query ) {
+		$meta_query = array();
+
+		foreach ( $tax_query as $tax_query_item ) {
+			$taxonomy = $tax_query_item['taxonomy'];
+			$terms    = $tax_query_item['terms'];
+
+			$meta_key = 'attribute_' . $taxonomy;
+
+			$meta_query[] = array(
+				'key'   => $meta_key,
+				'value' => $terms,
+			);
+
+			if ( isset( $tax_query_item['operator'] ) ) {
+				$meta_query[0]['compare'] = $tax_query_item['operator'];
+			}
+		}
+
+		return $meta_query;
+	}
+
 	/**
 	 * Get results of query.
 	 *