def language_middleware(get_response):
    """
    Middleware that allows overriding the active request language
    via the 'language_code' query parameter.
    """
    def middleware(request):
        language_code = request.GET.get('language_code')
        if language_code:
            request.LANGUAGE_CODE = language_code

        response = get_response(request)
        return response

    return middleware