Flask

import re
from flask import Flask, request
from doti18n import LocaleData

app = Flask(__name__)
i18n = LocaleData("locales")
pattern = re.compile(r"[a-z]{2}")

def get_language_code() -> str:
    accept_language = request.headers.get("Accept-Language")

    if not accept_language:
        return i18n.default_locale

    for match in re.finditer(pattern, accept_language):
        language_code = match.group()
        if language_code in i18n.loaded_locales:
            return language_code

    return i18n.default_locale

@app.route("/")
def main():
    language_code = get_language_code()
    t = i18n[language_code].main

    return {"message": t.hello}

if __name__ == "__main__":
    app.run(host="localhost", port=8000)

import re
from typing import Optional
from flask import Flask, request, g
from doti18n import LocaleData

app = Flask(__name__)
i18n = LocaleData("locales")
pattern = re.compile(r"[a-z]{2}")

def _get_best_match_language(accept_language: Optional[str]) -> str:
    if not accept_language:
        return i18n.default_locale

    for match in re.finditer(pattern, accept_language):
        language_code = match.group()
        if language_code in i18n.loaded_locales:
            return language_code

    return i18n.default_locale

@app.before_request
def detect_language():
    accept_language = request.headers.get('Accept-Language')
    language = _get_best_match_language(accept_language)

    g.locale = language

@app.route("/")
def main():
    t = i18n[g.locale].main

    return {"message": t.hello}

if __name__ == "__main__":
    app.run(host="localhost", port=8000)