From c6ff0b797edf96b50abf171de665be48bb9932f9 Mon Sep 17 00:00:00 2001
From: codebymikey <50924-codebymikey@users.noreply.drupalcode.org>
Date: Tue, 21 Nov 2023 10:13:31 +0100
Subject: [PATCH] Issue #3402831 by codebymikey, mkalkbrenner: [sorting] Always
 set the multivalue's first value as long as it's not NULL

---
 src/Plugin/search_api/backend/SearchApiSolrBackend.php | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Plugin/search_api/backend/SearchApiSolrBackend.php b/src/Plugin/search_api/backend/SearchApiSolrBackend.php
index dd273872..6e1910ad 100644
--- a/src/Plugin/search_api/backend/SearchApiSolrBackend.php
+++ b/src/Plugin/search_api/backend/SearchApiSolrBackend.php
@@ -1381,7 +1381,7 @@ public function getDocuments(IndexInterface $index, array $items, UpdateQuery $u
         }
 
         // Enable sorts in some special cases.
-        if ($first_value && !array_key_exists($name, $special_fields)) {
+        if (($first_value !== NULL) && !array_key_exists($name, $special_fields)) {
           if (
             strpos($field_names[$name], 't') === 0 ||
             strpos($field_names[$name], 's') === 0
@@ -2636,7 +2636,7 @@ protected function hasHierarchicalProperties(EntityDataDefinitionInterface $prop
    * @param array $boost_terms
    *   Reference to an array where special boosts per term should be stored.
    *
-   * @return bool|float|int|string
+   * @return bool|float|int|string|null
    *   The first value of $values that has been added to the index.
    */
   protected function addIndexField(Document $doc, $key, array $values, $type, array &$boost_terms) {
@@ -2647,11 +2647,11 @@ protected function addIndexField(Document $doc, $key, array $values, $type, arra
     if (empty($values)) {
       if ('text' !== $type || !$this->configuration['index_empty_text_fields']) {
         // Don't index empty values (i.e., when field is missing).
-        return '';
+        return NULL;
       }
     }
 
-    $first_value = '';
+    $first_value = NULL;
 
     // All fields.
     foreach ($values as $value) {