# -*- coding: utf-8 -*-
"""
flask_babelex
~~~~~~~~~~~~~
Implements i18n/l10n support for Flask applications based on Babel.
:copyright: (c) 2013 by Serge S. Koval, Armin Ronacher and contributors.
:license: BSD, see LICENSE for more details.
"""
from __future__ import absolute_import
import os
# this is a workaround for a snow leopard bug that babel does not
# work around :)
if os.environ.get('LC_CTYPE', '').lower() == 'utf-8':
os.environ['LC_CTYPE'] = 'en_US.utf-8'
from datetime import datetime
from flask import _request_ctx_stack
from babel import dates, numbers, support, Locale
from babel.support import NullTranslations
from werkzeug.datastructures import ImmutableDict
try:
from pytz.gae import pytz
except ImportError:
from pytz import timezone, UTC
else:
timezone = pytz.timezone
UTC = pytz.UTC
from flask_babelex._compat import string_types
_DEFAULT_LOCALE = Locale.parse('en')
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',
date_formats=None, configure_jinja=True, default_domain=None):
self._default_locale = default_locale
self._default_timezone = default_timezone
self._date_formats = date_formats
self._configure_jinja = configure_jinja
self.app = app
self._locale_cache = dict()
if default_domain is None:
self._default_domain = Domain()
else:
self._default_domain = default_domain
self.locale_selector_func = None
self.timezone_selector_func = None
if app is not None:
self.init_app(app)
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)
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_domain().get_translations().ugettext(x),
lambda s, p, n: get_domain().get_translations().ungettext(s, p, n),
newstyle=True
)
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
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
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
"""
dirname = os.path.join(self.app.root_path, 'translations')
if not os.path.isdir(dirname):
return []
result = []
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 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 self.load_locale(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'])
def load_locale(self, locale):
"""Load locale by name and cache it. Returns instance of a `babel.Locale`
object.
"""
rv = self._locale_cache.get(locale)
if rv is None:
self._locale_cache[locale] = rv = Locale.parse(locale)
return rv
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. If flask-babel was not attached to the Flask application,
will return 'en' locale.
"""
ctx = _request_ctx_stack.top
if ctx is None:
return None
locale = getattr(ctx, 'babel_locale', None)
if locale is None:
babel = ctx.app.extensions.get('babel')
if babel is None:
locale = _DEFAULT_LOCALE
else:
if babel.locale_selector_func is not None:
rv = babel.locale_selector_func()
if rv is None:
locale = babel.default_locale
else:
locale = babel.load_locale(rv)
else:
locale = babel.default_locale
ctx.babel_locale = locale
return locale
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. If flask-babel was not attached to application, will
return UTC timezone object.
"""
ctx = _request_ctx_stack.top
tzinfo = getattr(ctx, 'babel_tzinfo', None)
if tzinfo is None:
babel = ctx.app.extensions.get('babel')
if babel is None:
tzinfo = UTC
else:
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
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 = _request_ctx_stack.top
for key in 'babel_locale', 'babel_tzinfo':
if hasattr(ctx, key):
delattr(ctx, key)
def _get_format(key, format):
"""A small helper for the datetime formatting functions. Looks up
format defaults for different kinds.
"""
babel = _request_ctx_stack.top.app.extensions.get('babel')
if babel is not None:
formats = babel.date_formats
else:
formats = Babel.default_date_formats
if format is None:
format = formats[key]
if format in ('short', 'medium', 'full', 'long'):
rv = formats['%s.%s' % (key, format)]
if rv is not None:
format = rv
return format
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))
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)
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)
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)
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)
def format_timedelta(datetime_or_timedelta, granularity='second'):
"""Format the elapsed time from the given date to now or the given
timedelta. This currently requires an unreleased development
version of Babel.
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,
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)
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_number(number, locale=locale)
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)
def format_currency(number, currency, format=None):
"""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
:return: the formatted number
:rtype: unicode
"""
locale = get_locale()
return numbers.format_currency(
number, currency, format=format, locale=locale
)
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)
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, dirname=None, domain='messages'):
self.dirname = dirname
self.domain = domain
self.cache = dict()
def as_default(self):
"""Set this domain as default for the current request"""
ctx = _request_ctx_stack.top
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_path(self, ctx):
"""Returns translations directory path. Override if you want
to implement custom behavior.
"""
return self.dirname or os.path.join(ctx.app.root_path, 'translations')
def get_translations(self):
"""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.
"""
ctx = _request_ctx_stack.top
if ctx is None:
return NullTranslations()
locale = get_locale()
cache = self.get_translations_cache(ctx)
translations = cache.get(str(locale))
if translations is None:
dirname = self.get_translations_path(ctx)
translations = support.Translations.load(dirname,
locale,
domain=self.domain)
cache[str(locale)] = 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 variables:
return t.ugettext(string) % variables
else:
return t.ugettext(string)
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()
return t.ungettext(singular, plural, num) % variables
def pgettext(self, context, string, **variables):
"""Like :func:`gettext` but with a context.
.. versionadded:: 0.7
"""
t = self.get_translations()
return t.upgettext(context, string) % 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()
return t.unpgettext(context, singular, plural, num) % 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)
"""
from speaklater import make_lazy_string
return make_lazy_string(self.gettext, string, **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
"""
from speaklater import make_lazy_string
return make_lazy_string(self.pgettext, context, string, **variables)
# This is the domain that will be used if there is no request context (and thus no app)
# or if the app isn't initialized for babel. Note that if there is no request context,
# then the standard Domain will use NullTranslations
domain = Domain()
def get_domain():
"""Return the correct translation domain that is used for this request.
This will return the default domain (e.g. "messages" in <approot>/translations")
if none is set for this request.
"""
ctx = _request_ctx_stack.top
if ctx is None:
return domain
try:
return ctx.babel_domain
except AttributeError:
pass
babel = ctx.app.extensions.get('babel')
if babel is not None:
d = babel._default_domain
else:
d = domain
ctx.babel_domain = d
return d
# Create shortcuts for the default Flask domain
def gettext(*args, **kwargs):
return get_domain().gettext(*args, **kwargs)
_ = gettext
def ngettext(*args, **kwargs):
return get_domain().ngettext(*args, **kwargs)
def pgettext(*args, **kwargs):
return get_domain().pgettext(*args, **kwargs)
def npgettext(*args, **kwargs):
return get_domain().npgettext(*args, **kwargs)
def lazy_gettext(*args, **kwargs):
from speaklater import make_lazy_string
return make_lazy_string(gettext, *args, **kwargs)
def lazy_pgettext(*args, **kwargs):
from speaklater import make_lazy_string
return make_lazy_string(pgettext, *args, **kwargs)