FastAPI

import re
from typing import Annotated
from fastapi import FastAPI, APIRouter, Depends, Header
from doti18n import LocaleData

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

async def get_language_code(accept_language: str = Header(alias="Accept-Language")) -> 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

@router.get("/")
async def main(language_code: Annotated[str, Depends(get_language_code)]):
    t = i18n[language_code].main

    return {"message": t.hello}

app.include_router(router)

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

import re
from typing import Optional
from fastapi import FastAPI, Request, APIRouter
from starlette.middleware.base import BaseHTTPMiddleware
from doti18n import LocaleData

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

class I18nMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        accept_language = request.headers.get('accept-language')
        language = self._get_best_match_language(accept_language)
        request.state.locale = language
        response = await call_next(request)
        return response

    @staticmethod
    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

@router.get("/")
async def main(request: Request):
    t = i18n[request.state.locale].main

    return {"message": t.hello}


app.add_middleware(I18nMiddleware)
app.include_router(router)


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