$_SESSION based language selection is not working properly - php

Question

My website has two languages: English and Russian. These languages' database names are EN and RU.
I use an old php+smarty script. This script's default language selection codes like this:
if(!isset($_SESSION)){
define('LANGUAGE_ID', 'EN');
} else if ($_SESSION['language'] == '')
{
define('LANGUAGE_ID', 'EN');
}
When I want to see a page in Russian, I visit any page with language phrase (?language=RU) like this:
http://www.example.com/index.php?language=RU
But these pages doesn't load in Russian firstly. When I clicked another link or refresh the page, then page loading in Russian. After saved the cookies, then I can see the pages in Russian when first visit. But If I delete the cookies in browser, then I couldn't see in Russian when first visit.
I tried lots of combinations but I couldn't find any solution. Do you have any idea?
Thank you very much...
Edit:
I found some codes in main.class.php:
function __construct($dbh,$smartyBuild) {
$this->dbh = $dbh;
$this->sitevar = #$smartyBuild->FetchSiteVar();
$this->smartybuild = #$smartyBuild;
if($_REQUEST['language'] !='')
{
$_SESSION['language'] = $_REQUEST['language'];
}
else
{
$langaugeAlready = mysql_fetch_array(mysql_query("select value from ".TABLE_PREFIX."sitevars where array_key = 'default_language_feed'"));
if($_SESSION['language'] == '')
{
$_SESSION['language'] = $langaugeAlready['value'];
}
}
if($_SESSION['language'] !='' )
{
define('LANGUAGE_ID', $_SESSION['language']);
}
else
{
define('LANGUAGE_ID', 'EN');
$_SESSION['language'] = 'EN';
}
}
Is the problem related with these codes?

Answer 1

Like I say, without all the code we are guessing a bit at what the problem is but, here goes...
It seems like you're only checking the $_SESSION variable for the language and not the $_GET variable (which gets the language from the URL). Therefore the value only changes after you refresh the page.
Try this. I am assuming your intention is to show English as a default and only Russian if it is defined in the url, but once defined to keep that language until it is put in the URL again.
//start a session. must be called first on all pages you want it to work on
session_start();
//first check if there's a new language coming from the URL
if(isset($_GET['language']))
{
// if we have a new language setting from the URL, check which one and save it in the session.
// we check it is EN or RO before saving into the session since I don't know what you're using it for later. eg part of a DB query which would be a security risk if it is anything other than EN or RO.
if($_GET['language'] == 'EN')
{
$_SESSION['language'] = 'EN';
}
if($_GET['language'] == 'RO')
{
$_SESSION['language'] = 'RO';
}
}
//now check the session variable, which will have been updated above if changed
if(isset($_SESSION['language']))
{
// already have a language saved, so let's use it
define('LANGUAGE_ID', $_SESSION['language']);
}
else
{
// no language from URL and no language saved, so default to english
define('LANGUAGE_ID', 'EN');
}