includes/query/class-tmdo-post-query-router.php

@@ -191,6 +191,25 @@ class TMDO_Post_Query_Router {
 			$routed[ $pt ][] = $route;
 			$sort            = self::sort_for( $pt, $route, $direction );
 		}
+		// meta_key alone (no meta_value, not a meta_value sort): WP_Query adds a
+		// clause that tests the key exists — HivePress's featured-listing lookup.
+		$exists_key = ! $take_key && is_string( $meta_key ) && '' !== $meta_key
+			&& '' === (string) $query->get( 'meta_value' ) && '' === (string) $query->get( 'meta_compare' )
+			&& ! in_array( $sort_name, array( 'meta_value', 'meta_value_num' ), true )
+			&& null !== self::field_for( array( 'key' => $meta_key ), $pt );
+		if ( $exists_key ) {
+			$route = self::route_clause(
+				array(
+					'key'     => $meta_key,
+					'compare' => 'EXISTS',
+				),
+				self::field_for( array( 'key' => $meta_key ), $pt )
+			);
+			if ( ! $route ) {
+				return;
+			}
+			$routed[ $pt ][] = $route;
+		}
 
 		foreach ( $raw_meta_query as $k => $clause ) {
 			if ( 'relation' === $k || ! is_array( $clause ) ) {
@@ -199,7 +218,10 @@ class TMDO_Post_Query_Router {
 			}
 			if ( ! isset( $clause['key'] ) ) {
 				// Sort shape: matches every post, only orders by the key.
-				$name  = 'AND' === $relation ? self::sort_shape( $clause ) : '';
+				$name = 'AND' === $relation ? self::sort_shape( $clause ) : '';
+				if ( '' !== $name && ! in_array( $name, $named, true ) && self::field_for( $clause[ $name ], $pt ) ) {
+					continue; // Matches every post and orders nothing here (a copy of a search's meta query).
+				}
 				$field = '' !== $name && $name === $sort_name ? self::field_for( $clause[ $name ], $pt ) : null;
 				if ( $field ) {
 					$route = self::route_clause( array( 'compare' => 'EXISTS' ) + $clause[ $name ], $field );
@@ -239,7 +261,7 @@ class TMDO_Post_Query_Router {
 		if ( empty( $routed ) && empty( $sort ) ) {
 			return;
 		}
-		if ( $take_key ) {
+		if ( $take_key || $exists_key ) {
 			$query->set( 'meta_key', '' );
 		}
 		if ( $sort ) {

tests/integration/PostQueryRouterTest.php

@@ -436,4 +436,47 @@ class PostQueryRouterTest extends TestCase {
 		$this->assertEmpty( $query->get( 'meta_query' ), 'both clauses routed' );
 		$this->assertStringContainsString( '`_stock` IS NOT NULL', $router->posts_where( '', $query ) );
 	}
+
+	/**
+	 * HivePress's featured-listing lookup (Attribute::set_search_query()): the
+	 * search's meta query, including its sort group, plus meta_key hp_featured,
+	 * ordered at random. The sort group (key NOT EXISTS OR key EXISTS) matches
+	 * every post, so unused for ordering it is dropped; meta_key without a
+	 * value or a meta_value sort tests that the key exists (2.4 PR-122).
+	 */
+	public function test_hivepress_featured_lookup_is_routed(): void {
+		$this->set_post_mode( 'aeav_only' );
+		$router = new WPDO_Post_Query_Router();
+		$query  = $this->make_query(
+			array(
+				'post_type'  => 'product',
+				'meta_key'   => '_stock',
+				'orderby'    => 'rand',
+				'meta_query' => array(
+					array(
+						'relation'      => 'OR',
+						'price__order' => array( 'key' => '_price', 'compare' => 'NOT EXISTS', 'type' => 'DECIMAL' ),
+						array( 'key' => '_price', 'compare' => 'EXISTS', 'type' => 'DECIMAL' ),
+					),
+					array( 'key' => '_price', 'value' => array( 10, 20 ), 'compare' => 'BETWEEN', 'type' => 'NUMERIC' ),
+				),
+			)
+		);
+		$router->pre_get_posts( $query );
+
+		$this->assertSame( '', $query->get( 'meta_key' ), 'meta_key routed' );
+		$this->assertEmpty( array_filter( (array) $query->get( 'meta_query' ), 'is_array' ), 'sort group dropped, filter routed' );
+		$where = $router->posts_where( '', $query );
+		$this->assertStringContainsString( '`_stock` IS NOT NULL', $where );
+		$this->assertStringContainsString( 'BETWEEN', $where );
+	}
+
+	public function test_meta_key_with_a_value_is_left_alone(): void {
+		$this->set_post_mode( 'aeav_only' );
+		$router = new WPDO_Post_Query_Router();
+		$query  = $this->make_query( array( 'post_type' => 'product', 'meta_key' => '_stock', 'meta_value' => '5' ) );
+		$router->pre_get_posts( $query );
+
+		$this->assertSame( '_stock', $query->get( 'meta_key' ) );
+	}
 }