Source code for flask_babel

# -*- coding: utf-8 -*-
"""
    flaskext.babel
    ~~~~~~~~~~~~~~

    Implements i18n/l10n support for Flask applications based on Babel.

    :copyright: (c) 2013 by Armin Ronacher, Daniel Neuhäuser.
    :license: BSD, see LICENSE for more details.
"""
from __future__ import absolute_import
import os

from datetime import datetime
from contextlib import contextmanager
from flask import current_app, request
from flask.ctx import has_request_context
from flask.helpers import locked_cached_property
from babel import dates, numbers, support, Locale
from pytz import timezone, UTC
from werkzeug.datastructures import ImmutableDict

from flask_babel._compat import string_types
from flask_babel.speaklater import LazyString


[docs]class Babel(object): """Central controller class that can be used to configure how Flask-Babel behaves. Each application that wants to use Flask-Babel has to create, or run :meth:`init_app` on, an instance of this class after the configuration was initialized. """ default_date_formats = ImmutableDict({ 'time': 'medium', 'date': 'medium', 'datetime': 'medium', 'time.short': None, 'time.medium': None, 'time.full': None, 'time.long': None, 'date.short': None, 'date.medium': None, 'date.full': None, 'date.long': None, 'datetime.short': None, 'datetime.medium': None, 'datetime.full': None, 'datetime.long': None, }) def __init__(self, app=None, default_locale='en', default_timezone='UTC', default_domain='messages', date_formats=None, configure_jinja=True): self._default_locale = default_locale self._default_timezone = default_timezone self._default_domain = default_domain self._date_formats = date_formats self._configure_jinja = configure_jinja self.app = app self.locale_selector_func = None self.timezone_selector_func = None if app is not None: self.init_app(app)
[docs] def init_app(self, app): """Set up this instance for use with *app*, if no app was passed to the constructor. """ self.app = app app.babel_instance = self if not hasattr(app, 'extensions'): app.extensions = {} app.extensions['babel'] = self app.config.setdefault('BABEL_DEFAULT_LOCALE', self._default_locale) app.config.setdefault('BABEL_DEFAULT_TIMEZONE', self._default_timezone) app.config.setdefault('BABEL_DOMAIN', self._default_domain) if self._date_formats is None: self._date_formats = self.default_date_formats.copy() #: a mapping of Babel datetime format strings that can be modified #: to change the defaults. If you invoke :func:`format_datetime` #: and do not provide any format string Flask-Babel will do the #: following things: #: #: 1. look up ``date_formats['datetime']``. By default ``'medium'`` #: is returned to enforce medium length datetime formats. #: 2. ``date_formats['datetime.medium'] (if ``'medium'`` was #: returned in step one) is looked up. If the return value #: is anything but `None` this is used as new format string. #: otherwise the default for that language is used. self.date_formats = self._date_formats if self._configure_jinja: app.jinja_env.filters.update( datetimeformat=format_datetime, dateformat=format_date, timeformat=format_time, timedeltaformat=format_timedelta, numberformat=format_number, decimalformat=format_decimal, currencyformat=format_currency, percentformat=format_percent, scientificformat=format_scientific, ) app.jinja_env.add_extension('jinja2.ext.i18n') app.jinja_env.install_gettext_callables( lambda x: get_translations().ugettext(x), lambda s, p, n: get_translations().ungettext(s, p, n), newstyle=True )
[docs] def localeselector(self, f): """Registers a callback function for locale selection. The default behaves as if a function was registered that returns `None` all the time. If `None` is returned, the locale falls back to the one from the configuration. This has to return the locale as string (eg: ``'de_AT'``, ``'en_US'``) """ assert self.locale_selector_func is None, \ 'a localeselector function is already registered' self.locale_selector_func = f return f
[docs] def timezoneselector(self, f): """Registers a callback function for timezone selection. The default behaves as if a function was registered that returns `None` all the time. If `None` is returned, the timezone falls back to the one from the configuration. This has to return the timezone as string (eg: ``'Europe/Vienna'``) """ assert self.timezone_selector_func is None, \ 'a timezoneselector function is already registered' self.timezone_selector_func = f return f
[docs] def list_translations(self): """Returns a list of all the locales translations exist for. The list returned will be filled with actual locale objects and not just strings. .. versionadded:: 0.6 """ result = [] for dirname in self.translation_directories: if not os.path.isdir(dirname): continue for folder in os.listdir(dirname): locale_dir = os.path.join(dirname, folder, 'LC_MESSAGES') if not os.path.isdir(locale_dir): continue if filter(lambda x: x.endswith('.mo'), os.listdir(locale_dir)): result.append(Locale.parse(folder)) # If not other translations are found, add the default locale. if not result: result.append(Locale.parse(self._default_locale)) return result
@property def default_locale(self): """The default locale from the configuration as instance of a `babel.Locale` object. """ return Locale.parse(self.app.config['BABEL_DEFAULT_LOCALE']) @property def default_timezone(self): """The default timezone from the configuration as instance of a `pytz.timezone` object. """ return timezone(self.app.config['BABEL_DEFAULT_TIMEZONE']) @property def domain(self): """The message domain for the translations as a string. """ return self.app.config['BABEL_DOMAIN']
[docs] @locked_cached_property def domain_instance(self): """The message domain for the translations. """ return Domain(domain=self.app.config['BABEL_DOMAIN'])
@property def translation_directories(self): directories = self.app.config.get( 'BABEL_TRANSLATION_DIRECTORIES', 'translations' ).split(';') for path in directories: if os.path.isabs(path): yield path else: yield os.path.join(self.app.root_path, path)
[docs]def get_translations(): """Returns the correct gettext translations that should be used for this request. This will never fail and return a dummy translation object if used outside of the request or if a translation cannot be found. """ return get_domain().get_translations()
[docs]def get_locale(): """Returns the locale that should be used for this request as `babel.Locale` object. This returns `None` if used outside of a request. """ ctx = _get_current_context() if ctx is None: return None locale = getattr(ctx, 'babel_locale', None) if locale is None: babel = current_app.extensions['babel'] if babel.locale_selector_func is None: locale = babel.default_locale else: rv = babel.locale_selector_func() if rv is None: locale = babel.default_locale else: locale = Locale.parse(rv) ctx.babel_locale = locale return locale
[docs]def get_timezone(): """Returns the timezone that should be used for this request as `pytz.timezone` object. This returns `None` if used outside of a request. """ ctx = _get_current_context() tzinfo = getattr(ctx, 'babel_tzinfo', None) if tzinfo is None: babel = current_app.extensions['babel'] if babel.timezone_selector_func is None: tzinfo = babel.default_timezone else: rv = babel.timezone_selector_func() if rv is None: tzinfo = babel.default_timezone else: if isinstance(rv, string_types): tzinfo = timezone(rv) else: tzinfo = rv ctx.babel_tzinfo = tzinfo return tzinfo
[docs]def refresh(): """Refreshes the cached timezones and locale information. This can be used to switch a translation between a request and if you want the changes to take place immediately, not just with the next request:: user.timezone = request.form['timezone'] user.locale = request.form['locale'] refresh() flash(gettext('Language was changed')) Without that refresh, the :func:`~flask.flash` function would probably return English text and a now German page. """ ctx = _get_current_context() for key in 'babel_locale', 'babel_tzinfo', 'babel_translations': if hasattr(ctx, key): delattr(ctx, key) if hasattr(ctx, 'forced_babel_locale'): ctx.babel_locale = ctx.forced_babel_locale
[docs]@contextmanager def force_locale(locale): """Temporarily overrides the currently selected locale. Sometimes it is useful to switch the current locale to different one, do some tasks and then revert back to the original one. For example, if the user uses German on the web site, but you want to send them an email in English, you can use this function as a context manager:: with force_locale('en_US'): send_email(gettext('Hello!'), ...) :param locale: The locale to temporary switch to (ex: 'en_US'). """ ctx = _get_current_context() if ctx is None: yield return orig_attrs = {} for key in ('babel_translations', 'babel_locale'): orig_attrs[key] = getattr(ctx, key, None) try: ctx.babel_locale = Locale.parse(locale) ctx.forced_babel_locale = ctx.babel_locale ctx.babel_translations = None yield finally: if hasattr(ctx, 'forced_babel_locale'): del ctx.forced_babel_locale for key, value in orig_attrs.items(): setattr(ctx, key, value)
def _get_format(key, format): """A small helper for the datetime formatting functions. Looks up format defaults for different kinds. """ babel = current_app.extensions['babel'] if format is None: format = babel.date_formats[key] if format in ('short', 'medium', 'full', 'long'): rv = babel.date_formats['%s.%s' % (key, format)] if rv is not None: format = rv return format
[docs]def to_user_timezone(datetime): """Convert a datetime object to the user's timezone. This automatically happens on all date formatting unless rebasing is disabled. If you need to convert a :class:`datetime.datetime` object at any time to the user's timezone (as returned by :func:`get_timezone` this function can be used). """ if datetime.tzinfo is None: datetime = datetime.replace(tzinfo=UTC) tzinfo = get_timezone() return tzinfo.normalize(datetime.astimezone(tzinfo))
[docs]def to_utc(datetime): """Convert a datetime object to UTC and drop tzinfo. This is the opposite operation to :func:`to_user_timezone`. """ if datetime.tzinfo is None: datetime = get_timezone().localize(datetime) return datetime.astimezone(UTC).replace(tzinfo=None)
[docs]def format_datetime(datetime=None, format=None, rebase=True): """Return a date formatted according to the given pattern. If no :class:`~datetime.datetime` object is passed, the current time is assumed. By default rebasing happens which causes the object to be converted to the users's timezone (as returned by :func:`to_user_timezone`). This function formats both date and time. The format parameter can either be ``'short'``, ``'medium'``, ``'long'`` or ``'full'`` (in which cause the language's default for that setting is used, or the default from the :attr:`Babel.date_formats` mapping is used) or a format string as documented by Babel. This function is also available in the template context as filter named `datetimeformat`. """ format = _get_format('datetime', format) return _date_format(dates.format_datetime, datetime, format, rebase)
[docs]def format_date(date=None, format=None, rebase=True): """Return a date formatted according to the given pattern. If no :class:`~datetime.datetime` or :class:`~datetime.date` object is passed, the current time is assumed. By default rebasing happens which causes the object to be converted to the users's timezone (as returned by :func:`to_user_timezone`). This function only formats the date part of a :class:`~datetime.datetime` object. The format parameter can either be ``'short'``, ``'medium'``, ``'long'`` or ``'full'`` (in which cause the language's default for that setting is used, or the default from the :attr:`Babel.date_formats` mapping is used) or a format string as documented by Babel. This function is also available in the template context as filter named `dateformat`. """ if rebase and isinstance(date, datetime): date = to_user_timezone(date) format = _get_format('date', format) return _date_format(dates.format_date, date, format, rebase)
[docs]def format_time(time=None, format=None, rebase=True): """Return a time formatted according to the given pattern. If no :class:`~datetime.datetime` object is passed, the current time is assumed. By default rebasing happens which causes the object to be converted to the users's timezone (as returned by :func:`to_user_timezone`). This function formats both date and time. The format parameter can either be ``'short'``, ``'medium'``, ``'long'`` or ``'full'`` (in which cause the language's default for that setting is used, or the default from the :attr:`Babel.date_formats` mapping is used) or a format string as documented by Babel. This function is also available in the template context as filter named `timeformat`. """ format = _get_format('time', format) return _date_format(dates.format_time, time, format, rebase)
[docs]def format_timedelta(datetime_or_timedelta, granularity='second', add_direction=False, threshold=0.85): """Format the elapsed time from the given date to now or the given timedelta. This function is also available in the template context as filter named `timedeltaformat`. """ if isinstance(datetime_or_timedelta, datetime): datetime_or_timedelta = datetime.utcnow() - datetime_or_timedelta return dates.format_timedelta( datetime_or_timedelta, granularity, threshold=threshold, add_direction=add_direction, locale=get_locale() )
def _date_format(formatter, obj, format, rebase, **extra): """Internal helper that formats the date.""" locale = get_locale() extra = {} if formatter is not dates.format_date and rebase: extra['tzinfo'] = get_timezone() return formatter(obj, format, locale=locale, **extra)
[docs]def format_number(number): """Return the given number formatted for the locale in request :param number: the number to format :return: the formatted number :rtype: unicode """ locale = get_locale() return numbers.format_decimal(number, locale=locale)
[docs]def format_decimal(number, format=None): """Return the given decimal number formatted for the locale in request :param number: the number to format :param format: the format to use :return: the formatted number :rtype: unicode """ locale = get_locale() return numbers.format_decimal(number, format=format, locale=locale)
[docs]def format_currency(number, currency, format=None, currency_digits=True, format_type='standard'): """Return the given number formatted for the locale in request :param number: the number to format :param currency: the currency code :param format: the format to use :param currency_digits: use the currency’s number of decimal digits [default: True] :param format_type: the currency format type to use [default: standard] :return: the formatted number :rtype: unicode """ locale = get_locale() return numbers.format_currency( number, currency, format=format, locale=locale, currency_digits=currency_digits, format_type=format_type )
[docs]def format_percent(number, format=None): """Return formatted percent value for the locale in request :param number: the number to format :param format: the format to use :return: the formatted percent number :rtype: unicode """ locale = get_locale() return numbers.format_percent(number, format=format, locale=locale)
[docs]def format_scientific(number, format=None): """Return value formatted in scientific notation for the locale in request :param number: the number to format :param format: the format to use :return: the formatted percent number :rtype: unicode """ locale = get_locale() return numbers.format_scientific(number, format=format, locale=locale)
class Domain(object): """Localization domain. By default will use look for tranlations in Flask application directory and "messages" domain - all message catalogs should be called ``messages.mo``. """ def __init__(self, translation_directories=None, domain='messages'): if isinstance(translation_directories, string_types): translation_directories = [translation_directories] self._translation_directories = translation_directories self.domain = domain self.cache = {} def __repr__(self): return '<Domain({!r}, {!r})>'.format(self._translation_directories, self.domain) @property def translation_directories(self): if self._translation_directories is not None: return self._translation_directories babel = current_app.extensions['babel'] return babel.translation_directories def as_default(self): """Set this domain as default for the current request""" ctx = _get_current_context() if ctx is None: raise RuntimeError("No request context") ctx.babel_domain = self def get_translations_cache(self, ctx): """Returns dictionary-like object for translation caching""" return self.cache def get_translations(self): ctx = _get_current_context() if ctx is None: return support.NullTranslations() cache = self.get_translations_cache(ctx) locale = get_locale() try: return cache[str(locale), self.domain] except KeyError: translations = support.Translations() for dirname in self.translation_directories: catalog = support.Translations.load( dirname, [locale], self.domain ) translations.merge(catalog) # FIXME: Workaround for merge() being really, really stupid. It # does not copy _info, plural(), or any other instance variables # populated by GNUTranslations. We probably want to stop using # `support.Translations.merge` entirely. if hasattr(catalog, 'plural'): translations.plural = catalog.plural cache[str(locale), self.domain] = translations return translations def gettext(self, string, **variables): """Translates a string with the current locale and passes in the given keyword arguments as mapping to a string formatting string. :: gettext(u'Hello World!') gettext(u'Hello %(name)s!', name='World') """ t = self.get_translations() if t is None: return string if not variables else string % variables s = t.ugettext(string) return s if not variables else s % variables def ngettext(self, singular, plural, num, **variables): """Translates a string with the current locale and passes in the given keyword arguments as mapping to a string formatting string. The `num` parameter is used to dispatch between singular and various plural forms of the message. It is available in the format string as ``%(num)d`` or ``%(num)s``. The source language should be English or a similar language which only has one plural form. :: ngettext(u'%(num)d Apple', u'%(num)d Apples', num=len(apples)) """ variables.setdefault('num', num) t = self.get_translations() if t is None: s = singular if num == 1 else plural return s if not variables else s % variables s = t.ungettext(singular, plural, num) return s if not variables else s % variables def pgettext(self, context, string, **variables): """Like :func:`gettext` but with a context. .. versionadded:: 0.7 """ t = self.get_translations() if t is None: return string if not variables else string % variables s = t.upgettext(context, string) return s if not variables else s % variables def npgettext(self, context, singular, plural, num, **variables): """Like :func:`ngettext` but with a context. .. versionadded:: 0.7 """ variables.setdefault('num', num) t = self.get_translations() if t is None: s = singular if num == 1 else plural return s if not variables else s % variables s = t.unpgettext(context, singular, plural, num) return s if not variables else s % variables def lazy_gettext(self, string, **variables): """Like :func:`gettext` but the string returned is lazy which means it will be translated when it is used as an actual string. Example:: hello = lazy_gettext(u'Hello World') @app.route('/') def index(): return unicode(hello) """ return LazyString(self.gettext, string, **variables) def lazy_ngettext(self, singular, plural, num, **variables): """Like :func:`ngettext` but the string returned is lazy which means it will be translated when it is used as an actual string. Example:: apples = lazy_ngettext(u'%(num)d Apple', u'%(num)d Apples', num=len(apples)) @app.route('/') def index(): return unicode(apples) """ return LazyString(self.ngettext, singular, plural, num, **variables) def lazy_pgettext(self, context, string, **variables): """Like :func:`pgettext` but the string returned is lazy which means it will be translated when it is used as an actual string. .. versionadded:: 0.7 """ return LazyString(self.pgettext, context, string, **variables) def _get_current_context(): if has_request_context(): return request if current_app: return current_app def get_domain(): ctx = _get_current_context() if ctx is None: # this will use NullTranslations return Domain() try: return ctx.babel_domain except AttributeError: pass babel = current_app.extensions['babel'] ctx.babel_domain = babel.domain_instance return ctx.babel_domain # Create shortcuts for the default Flask domain
[docs]def gettext(*args, **kwargs): return get_domain().gettext(*args, **kwargs)
_ = gettext
[docs]def ngettext(*args, **kwargs): return get_domain().ngettext(*args, **kwargs)
[docs]def pgettext(*args, **kwargs): return get_domain().pgettext(*args, **kwargs)
[docs]def npgettext(*args, **kwargs): return get_domain().npgettext(*args, **kwargs)
[docs]def lazy_gettext(*args, **kwargs): return LazyString(gettext, *args, **kwargs)
[docs]def lazy_pgettext(*args, **kwargs): return LazyString(pgettext, *args, **kwargs)
def lazy_ngettext(*args, **kwargs): return LazyString(ngettext, *args, **kwargs)