Illuminate\Database\Eloquent\Model::isDirty PHP Method

    public function isDirty($attributes = null)
    {
        $dirty = $this->getDirty();
        if (is_null($attributes)) {
            return count($dirty) > 0;
        }
        if (!is_array($attributes)) {
            $attributes = func_get_args();
        }
        foreach ($attributes as $attribute) {
            if (array_key_exists($attribute, $dirty)) {
                return true;
            }
        }
        return false;
    }

 public function updated(Model $model)
 {
     if ($model->isDirty('parent_id')) {
         /**
          * 同步Original数据，是為了清除parent_id的dirty狀態
          */
         $model->syncOriginal();
         $tableName = $model->getTable();
         $oldNode = $model->getOriginal('node');
         if (0 < $model->parent_id) {
             /**
              * @var Model  $parent
              */
             $parent = $model->find($model->parent_id);
             $model->node = $parent->node . $model->id . self::SEPARATOR;
             $model->save();
             //取出原来的level
             $originalLevel = Cache::pull('node-category-original-level-' . $model->id);
             //计算新level与原来的level的差值
             $i = $model->level - $originalLevel;
             DB::table($tableName)->where('node', 'like', $oldNode . '%')->where('id', '<>', $model->id)->update(['level' => DB::raw("level + {$i}"), 'node' => DB::raw("REPLACE(`node`, '{$oldNode}', '{$model->node}')")]);
         } else {
             //修改為頂級分類
             $model->level = 1;
             $model->node = self::SEPARATOR . $model->id . self::SEPARATOR;
             $model->save();
             DB::table($tableName)->where('node', 'like', $oldNode . '%')->where('id', '<>', $model->id)->update(['level' => DB::raw("level - {$model->level}"), 'node' => DB::raw("CONCAT('{$model->node}', `id`, ',')")]);
         }
     }
 }