Fix non-parent issue

src/Controller/HmTaxonomyController.php

@@ -164,39 +164,49 @@ class HmTaxonomyController extends ControllerBase {
       // Children of the parent term in weight and name alphabetically order.
       $children = $this->storageController->loadTree($vid, $parent_id, 1);
       if (empty($children)) {
-        return new JsonResponse(['result' => 'fail']);
+        if (Term::load($parent_id)) {
+          // The parent term hasn't had any children.
+          $weight = 0;
+        }
+        else {
+          // The parent term doesn't exist.
+          return new JsonResponse(['result' => 'fail']);
+        }
       }
-      
-      $target_position = intval($target_position);
-      $total = count($children);
-      // Move all terms after the target position forward.
-      if (isset($children[$target_position])) {
-        $weight = (int) $children[$target_position]->weight;
-        $tids = [];
-        $step = $weight + count($updated_terms);
-        for ($i = $target_position; $i < $total; $i++) {
-          if ($children[$i]->weight < $step++) {
-            $tids[] = $children[$i]->tid;
+      else {
+        // The parent term has children.
+        $target_position = intval($target_position);
+        $total = count($children);
+        // Move all terms after the target position forward.
+        if (isset($children[$target_position])) {
+          $weight = (int) $children[$target_position]->weight;
+          $tids = [];
+          $step = $weight + count($updated_terms);
+          for ($i = $target_position; $i < $total; $i++) {
+            if ($children[$i]->weight < $step++) {
+              $tids[] = $children[$i]->tid;
+            }
+            else {
+              // There is planty room, no need to move anymore.
+              break;
+            }
           }
-          else {
-            // There is planty room, no need to move anymore.
-            break;
+          $step = $weight + count($updated_terms);
+          $term_siblings = Term::loadMultiple($tids);
+          foreach ($term_siblings as $term) {
+            $term->setWeight($step++);
+            $success = $term->save();
           }
         }
-        $step = $weight + count($updated_terms);
-        $term_siblings = Term::loadMultiple($tids);
-        foreach ($term_siblings as $term) {
-          $term->setWeight($step++);
-          $success = $term->save();
+        elseif ($target_position === $total) {
+          // Insert into the end.
+          $weight = intval(array_slice($children, -1)[0]->weight) + 1;
+        }
+        else {
+          return new JsonResponse(['result' => 'The term is not found.']);
         }
       }
-      elseif ($target_position === $total) {
-        // Insert into the end.
-        $weight = intval(array_slice($children, -1)[0]->weight) + 1;
-      }
-      else {
-        return new JsonResponse(['result' => 'The term is not found.']);
-      }
+      
       // Load all terms needed to update.
       $terms = Term::loadMultiple($updated_terms);
       // Update all terms, the weight will be increased by 1,

src/Plugin/HmDisplayPlugin/HmDisplayJstree.php

@@ -51,7 +51,7 @@ class HmDisplayJstree extends HmDisplayPluginBase implements HmDisplayPluginInte
       
       $form['jstree'] = [
         '#type' => 'html_tag',
-        '#suffix' => '<div class="description">' . $this->t('You can double click a tree node to edit it.') . '<br>' . $this->t('The tree node is draggable and droppable') . '</div>',
+        '#suffix' => '<div class="description">' . $this->t('Click a tree node to edit it.') . '<br>' . $this->t('The tree node is draggable and droppable') . '</div>',
         '#tag' => 'div',
         '#value' => '',
         '#attributes' => [