yii\mongodb\file\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) {
                $values[$key] = isset($currentAttributes[$key]) ? $currentAttributes[$key] : null;
            }
        }
        $collection = static::getCollection();
        if (isset($values['newFileContent'])) {
            $newFileContent = $values['newFileContent'];
            unset($values['newFileContent']);
        }
        if (isset($values['file'])) {
            $newFile = $values['file'];
            unset($values['file']);
        }
        if (isset($newFileContent)) {
            $newId = $collection->insertFileContent($newFileContent, $values);
        } elseif (isset($newFile)) {
            $fileName = $this->extractFileName($newFile);
            $newId = $collection->insertFile($fileName, $values);
        } else {
            $newId = $collection->insert($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;
    }