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Your IP : 216.73.216.124
"""
flask_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.
"""
import os
from dataclasses import dataclass
from types import SimpleNamespace
from datetime import datetime
from contextlib import contextmanager
from typing import List, Callable, Optional, Union
from babel.support import Translations, NullTranslations
from flask import current_app, g
from babel import dates, numbers, support, Locale
from pytz import timezone, UTC
from werkzeug.datastructures import ImmutableDict
from werkzeug.utils import cached_property
from flask_babel.speaklater import LazyString
@dataclass
class BabelConfiguration:
"""Application-specific configuration for Babel."""
default_locale: str
default_timezone: str
default_domain: str
default_directories: List[str]
translation_directories: List[str]
instance: 'Babel'
locale_selector: Optional[Callable] = None
timezone_selector: Optional[Callable] = None
def get_babel(app=None) -> 'BabelConfiguration':
app = app or current_app
if not hasattr(app, 'extensions'):
app.extensions = {}
return app.extensions['babel']
class Babel:
"""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, date_formats=None, configure_jinja=True, *args,
**kwargs):
"""Creates a new Babel instance.
If an application is passed, it will be configured with the provided
arguments. Otherwise, :meth:`init_app` can be used to configure the
application later.
"""
self._configure_jinja = configure_jinja
self.date_formats = date_formats
if app is not None:
self.init_app(app, *args, **kwargs)
def init_app(self, app, default_locale='en', default_domain='messages',
default_translation_directories='translations',
default_timezone='UTC', locale_selector=None,
timezone_selector=None):
"""
Initializes the Babel instance for use with this specific application.
:param app: The application to configure
:param default_locale: The default locale to use for this application
:param default_domain: The default domain to use for this application
:param default_translation_directories: The default translation
directories to use for this
application
:param default_timezone: The default timezone to use for this
application
:param locale_selector: The function to use to select the locale
for a request
:param timezone_selector: The function to use to select the
timezone for a request
"""
if not hasattr(app, 'extensions'):
app.extensions = {}
directories = app.config.get(
'BABEL_TRANSLATION_DIRECTORIES',
default_translation_directories
).split(';')
app.extensions['babel'] = BabelConfiguration(
default_locale=app.config.get(
'BABEL_DEFAULT_LOCALE',
default_locale
),
default_timezone=app.config.get(
'BABEL_DEFAULT_TIMEZONE',
default_timezone
),
default_domain=app.config.get(
'BABEL_DOMAIN',
default_domain
),
default_directories=directories,
translation_directories=list(
self._resolve_directories(directories, app)
),
instance=self,
locale_selector=locale_selector,
timezone_selector=timezone_selector
)
# 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.
if self.date_formats is None:
self.date_formats = self.default_date_formats.copy()
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(
gettext=lambda s: get_translations().ugettext(s),
ngettext=lambda s, p, n: get_translations().ungettext(s, p, n),
newstyle=True,
pgettext=lambda c, s: get_translations().upgettext(c, s),
npgettext=lambda c, s, p, n: get_translations().unpgettext(
c, s, p, n
),
)
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.
.. note::
The default locale will always be returned, even if no translation
files exist for it.
.. versionadded:: 0.6
"""
result = []
for dirname in get_babel().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 any(x.endswith('.mo') for x in os.listdir(locale_dir)):
result.append(Locale.parse(folder))
if self.default_locale not in result:
result.append(self.default_locale)
return result
@property
def default_locale(self) -> Locale:
"""The default locale from the configuration as an instance of a
`babel.Locale` object.
"""
return Locale.parse(get_babel().default_locale)
@property
def default_timezone(self) -> timezone:
"""The default timezone from the configuration as an instance of a
`pytz.timezone` object.
"""
return timezone(get_babel().default_timezone)
@property
def domain(self) -> str:
"""The message domain for the translations as a string.
"""
return get_babel().default_domain
@cached_property
def domain_instance(self):
"""The message domain for the translations.
"""
return Domain(domain=self.domain)
@staticmethod
def _resolve_directories(directories: List[str], app=None):
for path in directories:
if os.path.isabs(path):
yield path
elif app is not None:
# We can only resolve relative paths if we have an application
# context.
yield os.path.join(app.root_path, path)
def get_translations() -> Union[Translations, NullTranslations]:
"""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 the request or if a translation cannot be found.
"""
return get_domain().get_translations()
def get_locale() -> Optional[Locale]:
"""Returns the locale that should be used for this request as
`babel.Locale` object. This returns `None` if used outside a request.
"""
ctx = _get_current_context()
if ctx is None:
return None
locale = getattr(ctx, 'babel_locale', None)
if locale is None:
babel = get_babel()
if babel.locale_selector is None:
locale = babel.instance.default_locale
else:
rv = babel.locale_selector()
if rv is None:
locale = babel.instance.default_locale
else:
locale = Locale.parse(rv)
ctx.babel_locale = locale
return locale
def get_timezone() -> Optional[timezone]:
"""Returns the timezone that should be used for this request as
a `pytz.timezone` object. This returns `None` if used outside a request.
"""
ctx = _get_current_context()
tzinfo = getattr(ctx, 'babel_tzinfo', None)
if tzinfo is None:
babel = get_babel()
if babel.timezone_selector is None:
tzinfo = babel.instance.default_timezone
else:
rv = babel.timezone_selector()
if rv is None:
tzinfo = babel.instance.default_timezone
else:
tzinfo = timezone(rv) if isinstance(rv, str) else 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 = _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
@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 website, but you want to email them 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) -> Optional[str]:
"""A small helper for the datetime formatting functions. Looks up
format defaults for different kinds.
"""
babel = get_babel()
if format is None:
format = babel.instance.date_formats[key]
if format in ('short', 'medium', 'full', 'long'):
rv = babel.instance.date_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 user'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 case 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 case 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 user'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 case 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: str = '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)
def format_number(number) -> str:
"""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)
def format_decimal(number, format=None) -> str:
"""Return the given decimal number formatted for the locale in the 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, currency_digits=True,
format_type='standard') -> str:
"""Return the given number formatted for the locale in the 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
)
def format_percent(number, format=None) -> str:
"""Return formatted percent value for the locale in the 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) -> str:
"""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, it will look for translations in the
Flask application directory and "messages" domain - all message catalogs
should be called ``messages.mo``.
Additional domains are supported passing a list of domain names to the
``domain`` argument, but note that in this case they must match a list
passed to ``translation_directories``, eg::
Domain(
translation_directories=[
"/path/to/translations/with/messages/domain",
"/another/path/to/translations/with/another/domain",
],
domains=[
"messages",
"myapp",
]
)
"""
def __init__(self, translation_directories=None, domain='messages'):
if isinstance(translation_directories, str):
translation_directories = [translation_directories]
self._translation_directories = translation_directories
self.domain = domain.split(';')
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
return get_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[0]]
except KeyError:
translations = support.Translations()
for index, dirname in enumerate(self.translation_directories):
domain = (
self.domain[0]
if len(self.domain) == 1
else self.domain[index]
)
catalog = support.Translations.load(
dirname,
[locale],
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[0]] = 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()
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()
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()
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()
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() -> Optional[SimpleNamespace]:
if not g:
return None
if not hasattr(g, "_flask_babel"):
g._flask_babel = SimpleNamespace()
return g._flask_babel # noqa
def get_domain() -> Domain:
ctx = _get_current_context()
if ctx is None:
# this will use NullTranslations
return Domain()
try:
return ctx.babel_domain
except AttributeError:
pass
ctx.babel_domain = get_babel().instance.domain_instance
return ctx.babel_domain
# Create shortcuts for the default Flask domain
def gettext(*args, **kwargs) -> str:
return get_domain().gettext(*args, **kwargs)
_ = gettext
def ngettext(*args, **kwargs) -> str:
return get_domain().ngettext(*args, **kwargs)
def pgettext(*args, **kwargs) -> str:
return get_domain().pgettext(*args, **kwargs)
def npgettext(*args, **kwargs) -> str:
return get_domain().npgettext(*args, **kwargs)
def lazy_gettext(*args, **kwargs) -> LazyString:
return LazyString(gettext, *args, **kwargs)
def lazy_pgettext(*args, **kwargs) -> LazyString:
return LazyString(pgettext, *args, **kwargs)
def lazy_ngettext(*args, **kwargs) -> LazyString:
return LazyString(ngettext, *args, **kwargs)
def lazy_npgettext(*args, **kwargs) -> LazyString:
return LazyString(npgettext, *args, **kwargs)