Hey Luigi, let's dig into why your language keeps switching on page refresh—this is a super common snag with cookie-based localization, so we’ll get this sorted out step by step.

1. First, Verify Your Cookie is Actually Persisting #

Start with the basics: confirm the language cookie is being saved and retained across refreshes. Open your browser’s dev tools (F12) → go to the Application tab → expand Cookies → select your site’s domain. Look for your language cookie (e.g., user_language):

• If it’s not present at all: Your cookie isn’t being set correctly. Check the code in cookie.language.php or wherever you handle language selection.
• If it disappears after refresh: You probably forgot to set an expiration time. By default, PHP cookies are session-only (deleted when the browser closes), so make sure you define a long enough expiry window.

Here’s an example of a properly configured cookie setup:

// Set cookie to last 30 days (adjust as needed)
$expire_time = time() + (30 * 24 * 60 * 60);
// The "/" path ensures the cookie works across your entire site
setcookie('user_language', $selected_lang, $expire_time, '/', '', false, true);
// Use the secure flag (last parameter) if your site uses HTTPS

2. Fix the Language Detection Logic Order #

The most frequent mistake is prioritizing your default language over the saved cookie. Your page load logic should follow this strict order:

1. Check if a valid language cookie exists → use that language
2. If no cookie, check the browser’s Accept-Language header → use the user’s preferred language
3. If neither, fall back to your default language (e.g., English)

Look at the language initialization code in header.php—if it sets the default first then checks the cookie, that’s backwards.

Bad example (causes refresh switches):

// Wrong! Default language overrides cookie on load
$current_lang = 'en';
if (isset($_COOKIE['user_language'])) {
    $current_lang = $_COOKIE['user_language'];
}

Good example:

// Correct order: cookie first, then fallback
$supported_langs = ['en', 'it', 'es']; // List your supported languages
$current_lang = 'en'; // Default fallback

// Validate cookie value to avoid invalid inputs
if (isset($_COOKIE['user_language']) && in_array($_COOKIE['user_language'], $supported_langs)) {
    $current_lang = $_COOKIE['user_language'];
} 
// Optional: Add browser language detection here if needed
elseif (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
    // Parse the Accept-Language header to pick a supported language
}

Validating the cookie value is critical—it prevents corrupted or invalid cookie values from breaking your site or triggering unexpected language switches.

3. Debug the Language Switcher in gestore.php #

If your language switcher lives in gestore.php, make sure it’s updating the cookie correctly and redirecting properly:

• After setting the cookie, redirect back to the current page (don’t just reload—this avoids retriggering default language logic).
• Always use exit after header() to stop any subsequent code that might overwrite the cookie.

Example of a solid switcher logic:

// gestore.php
if (isset($_POST['switch_language']) && in_array($_POST['switch_language'], $supported_langs)) {
    $selected_lang = $_POST['switch_language'];
    
    // Set the persistent cookie
    $expire_time = time() + (30 * 24 * 60 * 60);
    setcookie('user_language', $selected_lang, $expire_time, '/');
    
    // Redirect back to the previous page to ensure cookie is read on load
    header("Location: " . $_SERVER['HTTP_REFERER']);
    exit; // Stop all further code execution
}

4. Check for Conflicting Code in cookie.language.php #

If you have a dedicated file for cookie handling, make sure it’s not resetting the cookie on every page load:

• Is there code that unconditionally sets the cookie to your default language?
• Are you calling setcookie() without checking if the cookie already exists?

This file should only set the cookie when the user actively selects a language, not on every page refresh.

Quick Isolation Test #

To narrow down the issue:

1. Manually add a language cookie via your browser’s dev tools (name it user_language, set a value like it).
2. Refresh the page. If the language stays, your cookie reading logic works—but the switcher isn’t setting the cookie properly.
3. If it still switches, your language detection logic is ignoring the cookie.

If you can share snippets from your files (especially the language initialization and cookie-setting parts), I can help pinpoint the exact issue even faster!

内容的提问来源于stack exchange，提问作者Luigi Loria