yii\mongodb\ActiveRecord::insertInternal PHP Method

    protected function insertInternal($attributes = null)
    {
        if (!$this->beforeSave(true)) {
            return false;
        }
        $values = $this->getDirtyAttributes($attributes);
        if (empty($values)) {
            $currentAttributes = $this->getAttributes();
            foreach ($this->primaryKey() as $key) {
                if (isset($currentAttributes[$key])) {
                    $values[$key] = $currentAttributes[$key];
                }
            }
        }
        $newId = static::getCollection()->insert($values);
        if ($newId !== null) {
            $this->setAttribute('_id', $newId);
            $values['_id'] = $newId;
        }
        $changedAttributes = array_fill_keys(array_keys($values), null);
        $this->setOldAttributes($values);
        $this->afterSave(true, $changedAttributes);
        return true;
    }