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

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

According to the documentation, there is not such a fallback in Propel.
What you can try, is the combination of setLocale and joinWithI18N. Something like:
$default_locale = 'en_US';
$items = ItemQuery::create()
->joinWithI18n('fr_FR')
->find();
foreach ($items as $item)
{
echo $item->getPrice();
// test if name is translated
if (!$name = $item->getName())
{
// otherwise, try to get the translation with default locale
$item->setLocale($default_locale);
$name = $item->getName(); // one query to retrieve the English translation
}
}
I haven't tested this code but it seems to be a solution.
Also, have you tried to add two joinWithI18N (one for en_US & one for fr_FR) to see how the query handle it?

Answer 2

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.

Answer 3

Try something like this
public function joinWithI18nFallback($locale=null, $joinType = Criteria::LEFT_JOIN, $default_locale=null)
{
$languages = sfConfig::get('sf_languages');
if(null == $locale)
{
$locale = sfPropel::getDefaultCulture();
}
if(null == $default_locale)
{
$default_locale = sfPropel::getDefaultCulture();
}
$languages[] = $locale;
$languages[] = $default_locale;
$languages = array_unique($languages);
$FallbackQuery = CategoryQuery::create()
->leftJoin('CategoryI18n')
->addJoinCondition('CategoryI18n', "CategoryI18n.Culture IN ('".implode("','", $languages)."')" )
->withColumn('CategoryI18n.Culture', 'CultureDefault')
->addAscendingOrderByColumn("FIELD(category_i18n.culture, '".$locale."', '".implode("','", $languages)."' )")
->where("CategoryI18n.name != ''");
$this->addSelectQuery($FallbackQuery, 'Category')
->join('CategoryI18n', $joinType)
->addJoinCondition('CategoryI18n', 'CategoryI18n.Culture = Category.CultureDefault' )
->with('CategoryI18n')
->groupById();
$this->with['CategoryI18n']->setIsWithOneToMany(false);
return $this;
}