Propel Behavior for Localization
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README.md

Propel l10n Behavior

Build Status

The propel-l10n-behavior is an extension to propels own i18n behavior. Basically, it puts an API in front of the i18n behavior and let's you use propels default API but with localized content. You provide the localization you want to use once (globally) and you are ready to go.

Installation

Install via composer:

{
    "require": {
        "gossi/propel-l10n-behavior": "~0"
    }
}

Locale and Dependencies

When working with locales, you should know about the locales and dependencies you can define for the propel-l10n-behavior. There are three mechanisms:

  • Locale (That's the default locale, when retrieving localized content from a propel object)
  • Dependencies (This is a dependency chain, when a field is not available in the default locale)
  • Fallback (If nothing is found, try the fallback locale)

Set Default locale

Default locale is set to en but of course you can change this:

PropelL10n::setLocale('de');

echo PropelL10n::getLocale(); // de

The default locale can be overwritten per object, e.g. you have a Book model, this is how it works:

$book = new Book();
$book->setLocale('ja');

Now, the locale for book is japanese, while for all others it stays german (as seen in the example above). You can reset this object-related overwrite by setting the locale to null:

$book->setLocale(null);

The object default locale can be overwritten per call, e.g.

PropelL10n::setLocale('it');
$book = BookQuery::create() // locale: it
	->setLocale('ja') // locale: ja
	->findOneByTitle('Herr der Ringe', null, 'de') // locale: de
;
$book->setLocale('ja');
$book->setTitle('Lord of the Rings', 'en');

Set Fallback locale

Fallback locale also is defaulted to en, yet you can change that:

PropelL10n::setFallback('de');

echo PropelL10n::getFallback(); // de

Working with Dependencies

There is some API to work with dependencies:

// get and set one dependency
PropelL10n::addDependency('de-CH', 'de');
echo PropelL10n::getDependency('de-CH'); // de

// get and set all dependencies
PropelL10n::setDependencies([
	'de'	=> 'en',
	'de-CH' => 'de',
	'de-AT' => 'de'
]);
print_r(PropelL10n::getDependencies()); // outputs the array from above

// check if dependencies exist
PropelL10n::hasDependency('de'); // true
PropelL10n::hasDepdedency('ja'); // false

// count depdencies for a given locale
PropelL10n::setDependencies(['de' => 'en', 'de-CH' => 'de']);
PropelL10n::countDependencies('de-CH'); // 2

Retrieving a localized Field

Whenever you retrieve a localized field, the behavior will use the following algorithm to find the contents for the field in the most recent locale:

  1. Set default locale as locale.
  2. Try to get the field in the set locale
  3. If empty, check if the locale has a dependency and if yes a. if the primary language of the dependency and the current locale are different, work down the language-tag-chain of the current locale b. set dependency as new locale, continue with step 2
  4. If no dependecy is set for that locale, work down the language-tag-chain
  5. If primary language is empty, use fallback as new locale and continue with step 2
  6. Last step: giving up, return null

Language-tag-chain:

Given the following language-tag: de-DE-1996 it consists of three subtags. When working down the language-tag-chain it means, the last subtag is dropped and it will be tried to getting the content of a field for the remaining language-tag until there is only the primary language left.

Usage

In your schema.xml

The usage in your schema.xml is very similar to the i18n behavior.

<table name="book">
	<column name="id" type="INTEGER" primaryKey="true" required="true"
		autoIncrement="true" />
	<column name="title" type="VARCHAR" size="255" />
	<column name="author" type="VARCHAR" size="255" />

	<behavior name="l10n">
		<parameter name="i18n_columns" value="title" />
	</behavior>
</table>

The parameters are equal to the i18n parameters, except default_locale doesn't exist.

Using the API

There is three things you need to do once for your app and you are ready to go and use propel as if they weren't any l10n/i18n behaviors used at all.

  1. Set the default locale
  2. Set a fallback locale
  3. Set your dependencies

Example:

PropelL10n::setLocale('de'); // this is mostly the language a user decided to use
PropelL10n::setFallback('en'); // that's the default language of your app
PropelL10n::setDependencies([ // that's the locales you have available
	'de'	=> 'en'
	'de-CH' => 'de',
	'de-AT' => 'de',
	'ja' => 'en'
]);

And you are ready to go.

Retrieving from Objects

$book = new Book();
$book->setTitle('Lord of the Rings');
$book->setLocale('de');
$book->setTitle('Herr der Ringe');
$book->setLocale(null);

echo $book->getTitle(); // Lord of the Rings - using the default locale (`en`)
echo $book->getTitle('de-DE'); // Herr der Ringe
$book->setLocale('de-DE');
echo $book->getTitle(); // Herr der Ringe
echo $book->getTitle('ja-JP'); // Lord of the Rings - using fallback locale (`en`)

Querying the Database

You can use your well known methods to query the database:

// default locale: de

// contains all books with a german title starting with 'Harry Potter'
$books = BookQuery::create()
	->filterByTitle('Harry Potter%')
	->find();
$books = ...; 

// the book lord of the rings as searched with an english title name
$book = BookQuery::create()
	->findOneByTitle('Lord of the Rings', null, 'en');
$book = ...; 

// all harry potter books searched with the japanese title
$books = BookQuery::create()
	->setLocale('ja') 				// overwrites query default locale
	->findByTitle('Harī Pottā%');
$books = ...;

// find lord of the rings with the japanese title, overwrite locale with the filter method
$book = BookQuery::create()
	->findOneByTitle('Yubiwa Monogatari', null, 'ja');
$book = ...;

Best Practices

Use the shortest locale possible! Only use a longer language-tag, when it is necessary to be more specific. If there is no need, just go with de instead of de-DE (which is kind of redundant anyway). However, go with de and de-CH as there might be content available which is different for people in germany or switzerland (e.g. a contact address, one for germany the other for switzerland).

Performance

I'm pretty sure this is a performance nightmare. Only propel API methods are used, means no manual queries so far. Performance optimization can begin after propel will merge the data-mapper branch into master. Suggestions are welcome, please post the to the issue tracker.

References

There's a lot material about localization, language-tags. Sometimes it is about finding the right subtag, which can be complicated enough. Here are some good references:

Related Specifications: