Propel and I18N: fallback to another locale if first is not found

Question

I am currently working on a API allowing users to get some event messages on their devices. Users call my API specifying me their preferred locale (for instance fr_FR).

On the back-office, administrators can choose the languages they want to support. Let's assume they choose English and Chinese. So, they do not support French language.

I am using the Propel I18N behavior to deal with all the translations. In my requests, I am currently doing:

SystemMessageQuery::create()
    ->joinWithI18N('fr_FR')
    ->findOne();

It works correctly if I specify an existing locale. Yet, if the translation is not available, it returns null. Sounds logical.

My question is: can I fallback the user on a default locale (in this case, en_US) if the provided locale is not planned by an administrator? If yes, how can I proceed?

I thought to send a prior request to check if the locale exists. But I do not think it is a good way for performances reasons (especially for an API).

Any idea?

Answer 1

Finally, I used the following code:

public function setLocale($locale = 'en_US', $fallbackEnabled = false)
{
    if($fallbackEnabled) {

        $localeExists = SystemMessageI18nQuery::create()
            ->filterByLocale($locale)
            ->filterById($this->getId())
            ->count();

        if(!$localeExists) {
            $locale = SystemMessageI18nQuery::create()
                ->filterById($this->getId())
                ->select('locale')
                ->findOne();
        }

    }

    parent::setLocale($locale);
}

It is not the best solution for performance reasons, but it is functionnal.