Issue #268909 by maartenvg, raman.b, paulocs, lyricnz, Abhijith S, webchick,...

Issue #268909 by maartenvg, raman.b, paulocs, lyricnz, Abhijith S, webchick, Freso, chx, pameeela: "0" can't be used a path alias, but no error is shown

core/modules/path/src/Plugin/Field/FieldWidget/PathWidget.php

@@ -84,7 +84,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
   public static function validateFormElement(array &$element, FormStateInterface $form_state) {
     // Trim the submitted value of whitespace and slashes.
     $alias = rtrim(trim($element['alias']['#value']), " \\/");
-    if (!empty($alias)) {
+    if ($alias !== '') {
       $form_state->setValueForElement($element['alias'], $alias);
 
       /** @var \Drupal\path_alias\PathAliasInterface $path_alias */

core/modules/path/tests/src/Functional/PathAliasTest.php

@@ -345,6 +345,12 @@ public function testNodeAlias() {
     // Create sixth test node.
     $node6 = $this->drupalCreateNode();
 
+    // Test the special case where the alias is '0'.
+    $edit = ['path[0][alias]' => '0'];
+    $this->drupalGet($node6->toUrl('edit-form'));
+    $this->submitForm($edit, 'Save');
+    $this->assertSession()->pageTextContains('The alias path has to start with a slash.');
+
     // Create an invalid alias with two leading slashes and verify that the
     // extra slash is removed when the link is generated. This ensures that URL
     // aliases cannot be used to inject external URLs.