flask_jsonlocale.py

from flask import request, session
import os.path
import os
import simplejson as json


class Locales(object):
    def __init__(self, app):
        self.app = app
        self.init_app(app)
        self._messages = {}
    
    def init_app(self, app):
        app.config.setdefault('MESSAGES_DIR', 'messages')
        app.config.setdefault('DEFAULT_LANGUAGE', 'en')
        app.context_processor(self.messages_to_context)
        app.jinja_env.globals.update(get_message=self.get_message, _=self.get_message)

    def get_locale(self):
        return request.args.get('uselang') or session.get('language') or request.accept_languages.best_match(self.get_locales()) or self.app.config.get('DEFAULT_LANGUAGE')
    
    def get_permanent_locale(self):
        return session.get('language') or self.app.config.get('DEFAULT_LANGUAGE')
    
    def set_locale(self, language=None):
        session['language'] = language or self.app.config.get('DEFAULT_LANGUAGE')
    
    def _get_messages(self, language=None):
        if language is None: language = self.get_locale()
        if language in self._messages and not self.app.debug:
            return self._messages[language]
        language = language.replace('/', '-').replace('\\', '-') # no paths in language
        if language == "qqx":
            default_locales = json.loads(open(os.path.join(self.app.config.get('MESSAGES_DIR'), "%s.json" % self.app.config.get('DEFAULT_LANGUAGE'))).read())
            res = {}
            for key in default_locales:
                res[key] = key
            self._messages["qqx"] = res
            return res
        path = os.path.join(self.app.config.get('MESSAGES_DIR'), "%s.json" % language)
        falledback = False
        if not os.path.isfile(path):
            falledback = True
            path = os.path.join(self.app.config.get('MESSAGES_DIR'), "%s.json" % self.app.config.get('DEFAULT_LANGUAGE'))
            if not os.path.isfile(path):
                return {}
        messages = json.loads(open(path).read())
        if not falledback:
            self._messages[language] = messages
        return messages
    
    def get_message(self, message_code, language=None, **args):
        if language is None: language = self.get_locale()
        if language == 'qqx':
            return message_code
        message = self._get_messages(language=language).get(message_code,
            self._get_messages(language=self.app.config.get('DEFAULT_LANGUAGE')).get(message_code, "<%s>" % message_code)
        )
        message = message.format(**args)
        return message
    _ = get_message
    
    def get_locales(self):
        return [x.replace('.json', '') for x in os.listdir(self.app.config.get('MESSAGES_DIR'))]
    
    def messages_to_context(self):
        locales = self._get_messages()
        default_locales = self._get_messages(language=self.app.config.get('DEFAULT_LANGUAGE'))
        for key in default_locales.keys():
            if key not in locales.keys():
                locales[key] = default_locales[key]
        return {'locale': locales}