Lists all taxonomy metadata in tags list, even if from the same taxonomy from different collections. #778.

src/classes/api/endpoints/class-tainacan-rest-items-controller.php

@@ -434,29 +434,36 @@ class REST_Items_Controller extends REST_Controller {
 				return $t != false ? $t->name : '--';
 			}, $terms_id);
 
-			$metas = $this->metadatum_repository->fetch(array(
-				'meta_query' => [
-					[
-						'key'     => 'collection_id',
-						'value'   => empty($collection_id) ? 'default' : $collection_id,
-						'compare' => '='
-					],
+			$meta_query_params = [
 				[
 					'key'     => '_option_taxonomy_id',
 					'value'   => $taxonomy_id,
 					'compate' => '='
 				]
-				]
+			];
+
+			if ( !empty($collection_id) && $collection_id !== 'default' ) {
+				$meta_query_params[] = [
+					'key'     => 'collection_id',
+					'value'   => $collection_id,
+					'compare' => '='
+				];	
+			}
+
+			$metas = $this->metadatum_repository->fetch(array(
+				'meta_query' => $meta_query_params
 			), 'OBJECT' );
 
 			if ( !empty($metas) ) {
+				foreach( $metas as $meta ) {
 					$meta_query[] = array(
-					'key' => $metas[0]->get_id(),
+						'key' => $meta->get_id(),
 						'value' => $terms_id,
 						'label' => $terms_name,
 					);
 				}
 			}
+		}
 
 		foreach($meta_query as $meta) {