first

app/Models/QuestionnaireQuestion.php

@@ -7,16 +7,17 @@ use Illuminate\Database\Eloquent\Model;
 class QuestionnaireQuestion extends Model
 {
     protected $fillable = [
-        'questionnaire_set_id', 'question_text', 'question_type',
-        'options_json', 'is_required', 'sort_order',
+        'questionnaire_set_id', 'parent_id', 'question_text', 'question_type',
+        'options_json', 'rating_labels', 'is_required', 'sort_order',
     ];
 
     protected function casts(): array
     {
         return [
-            'options_json' => 'array',
-            'is_required'  => 'boolean',
-            'sort_order'   => 'integer',
+            'options_json'  => 'array',
+            'rating_labels' => 'array',
+            'is_required'   => 'boolean',
+            'sort_order'    => 'integer',
         ];
     }
 
@@ -25,6 +26,16 @@ class QuestionnaireQuestion extends Model
         return $this->belongsTo(QuestionnaireSet::class);
     }
 
+    public function parent()
+    {
+        return $this->belongsTo(QuestionnaireQuestion::class, 'parent_id');
+    }
+
+    public function children()
+    {
+        return $this->hasMany(QuestionnaireQuestion::class, 'parent_id')->orderBy('sort_order');
+    }
+
     public function answers()
     {
         return $this->hasMany(QuestionnaireAnswer::class);