prepping your app to handle multiple languages § Localization (L10N) is the process of adding the right resources to handle a particular language in your app
tags • {% trans "My Fruit Store" %} • {% blocktrans %} • Click <a href="{{ link }}">here</a>for more info • {% endblocktrans %} • {% blocktrans count counter=apple|length %} • Checkout my apple • {% plural %} • Checkout my {{ counter }} apples • {% endblocktrans %}
§ request.session['django_language'] § django_language cookie § Accept-Language HTTP header set by the browser based on language preferences § settings.LANGUAGE_CODE = 'en-us' § If you save user language preferences in your database, override the request session key in your own middleware class – – request.session['django_language'] = request.user.lang_pref
different domain to optimize the number of strings sent from the server • $ pybabel extract --mapping-file babel_js.cfg --output out_js.po . • # babel_js.cfg • [javascript: **.js] • extract_messages = $._, jQuery._ • [extractors] • javascript = babel.messages.extract:extract_javascript
with the received translation file • $ pybabel <init/update> --domain django<js> --locale de --input-file <po> • • updating catalog <LOCALE_PATH>/de/LC_MESSAGES/django.po based on input.po • updating catalog <LOCALE_PATH>/de/LC_MESSAGES/djangojs.po based on inputjs.po § Catalog is then compiled into efficient machine binaries (.mo) files • • $ pybabel compile --domain django<js> --locale de • • compiling catalog to <LOCALE_PATH>/de/LC_MESSAGES/django.mo • compiling catalog to <LOCALE_PATH>/de/LC_MESSAGES/djangojs.mo
File transfers, API integrations, PM intervention § Latency § Control feature roll-out by locale § Intermediate translations through Google APIs § Cost § Translation Memory § Scales better as you get translations for more locales
your application • # TRANSLATOR: The date fruit, not calendar date • str = ugettext("%(num)s dates") % {'num': date_count} • {% comment %}TRANSLATOR: The date fruit, not calendar date{% endcomment %} • • • $ pybabel extract --add-comments TRANSLATOR: <options> <dir> • #. TRANSLATOR: The date fruit, not calendar date • #: fruits/app.py:20 • msgid "%(num)s dates"
are in custom or extension template tags • {% autoescape false %} • {% trans %}"This text is safe, but Babel might miss me"{% endtrans %} • {% endautoescape %} • # Add comma-separated extensions option in babel.cfg • [jinja2: **.html] • extensions=jinja2.ext.autoescape,...
when constants, model and form fields are initialized § ugettext_lazy returns lazy string references that can be later evaluated in a locale-aware context • from django.utils.translation import ugettext_lazy • • class MyFruit(models.Model): • name = models.CharField(help_text=ugettext_lazy('Name your fruit!'))
do not know how to convert themselves to bytestring • In [1]: ugettext_lazy("Hello") • Out[1]: <django.utils.functional.__proxy__ at 0x6c8ec90> § Watch out for lazy string concats, bytestring interpolation, exception handlers and JSON encoding (needs LazyEncoder) • In [1]: "Hello %s" % ugettext_lazy("World") • Out[1]: 'Hello <django.utils.functional.__proxy__ object at 0x6d7c250>'
since it simply parses through files one line at a time • • # Babel will miss this by default • from django.utils.translation import ugettext_lazy as _lazy • lazy_str = _lazy("Lazy") • • # Need to explicitly mention other aliases • pybabel extract --keyword "_lazy" <options> <dir>
request. Browser can cache JS files, so it can be pre-generated at deploy time and served statically instead. • // i18n_de.js • var catalog = new Array(); • catalog["Welcome, %(user)s!"] = "Willkommen, %(user)s!”; • ... • function gettext(msgid) {...}; • function ngettext(singular, plural, count) {...}; • function interpolate(fmt, obj, named) {...};
rich enum classes instead • # Maps enum values, canonical names, display names • class MyFruitEnum(CoolEnum): • APPLE = _MyFruitValue(1, 'apple', ugettext_lazy('Apple')) • BANANA = _MyFruitValue(2, 'banana', ugettext_lazy('Banana')) § If you really need to do so, use django-dbgettext to make DB strings available in the message catalog
Python apps § Support for JS internationalization works really great for mobile web apps § Internationalize early and be ready for an international audience from day one!
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