Change language by clicking a button

Question

The goal is to offer a button/select drop-down or similar to switch the public interface¹⁾ language on the fly.

What I'm searching for

• Plugin or Theme Code...
• ... or Ideas
• Using a work-around with load_textdomain() would be appreciated to leave translation to .po/.mo files
• Ideas on how to parse the strings into the interface (ex. ajax/plain php/ini, json, xml files) when not relying on some textdomain function

---

Note:

1) It's not about publishing in different languages.

2) I don't need code to make the actual drop-down/button/whatever. It's only about the code/system delivering the strings for the UI.

Thanks!

Answer 1

By far the best (easiest) way is to use the locale filter (inside get_locale()).

First set up a quick function for retrieving a different language to use on the locale filter.

/**
 * A function returns with returns the user's selectd locale, if stored. 
 */
function wpse35622_get_new_locale($locale=false){
$new_locale = get_user_meta(get_current_user_id(), 'wpse_locale', true);
    if($new_locale)
        return $new_locale;

    return $locale;
}

I've left this as a global function, might be handy...? The rest of the plug-in I've wrapped inside a class.

It creates a drop-down of possible languages from which you can select.

Drawbacks

• Searches wp-content/languages for files of the form xx_xx.mo. If it's not of that form (not all .mo files are) the plug-in won't pick up on it!
• The drop down gives a list of the found locales to choose from, but these are displayed in the 'xx_xx` format of locales, not a human friendly way - any ideas??
• Does $locale do anything other than language? If so it's still possible to get the locale the same, but provide alternative translations. It's a lot messier though...

The code

class SH_Pick_Lang{
    /**
     * A unique name for this plug-in
     */
    static $name ='sh_pick_lang';

    /**
     * Hook the functions
     */
    public function __construct(){

        if( isset($_POST[self::$name]) ){
            add_action('locale',array($this,'update_user'));
        }
        add_filter( 'locale', 'wpse35622_get_new_locale',20 );
        add_action( 'wp_before_admin_bar_render', array( $this, 'admin_bar') );
    }

    /**
     * Update the user's option just in time! Only once mind...
     */
    function update_user($locale){
        $save_locale = $_POST[self::$name];
        update_user_meta(get_current_user_id(), 'wpse_locale', $save_locale);
        remove_filter(current_filter(),__FUNCTION__);
        return $locale;
    }

    /**
     * Add a really horrible looking dropdown menu that I'm sure Kaiser will make look fantastic.
     */
    function admin_bar(){
        global $wp_admin_bar;

        $wp_admin_bar->add_menu( array(
            'id'        => 'shlangpick',
            'title'     => $this->wpse_language_dropown(),
        ) );
    }

    /**
     * Generates a list of available locales.
     * Searches the wp-content/languages folder for files of the form xx_xx.mo
     * 
     * TODO Not all locales are of the form xx_xx.mo - we might miss some.
     * TODO Better way of gettin gthe wp-content/languages folder without a constant?
     */
    function wpse_language_dropown(){
         $name = self::$name;
         $locale = get_locale();
         $langs = get_available_languages();
         $langs[] = 'en_US';

         //For the labels (format_code_lang)
         require_once( ABSPATH . 'wp-admin/includes/ms.php');

         $html = "<form method='post'> ";
         $html .= "<select name='{$name}'>";
         foreach($langs as $lang){
              $label = format_code_lang( $lang );
              $html .= "<option ".selected( $lang, $locale, false)." value='{$lang}'>{$label}</option>";
        }
         $html .= "</select>";
         $html .= get_submit_button('Change Language','secondary', 'submit', true);
         $html .= "</form >";

         return $html;
    }

} // END Class

//Initiate...
$sh_pick_lang = new SH_Pick_Lang();

Answer 2

If you can settle for a page refresh, redefining the WPLANG constant could be an option. I'm doing that on two sites with multilingual content where the multilinguality plugin fails to trigger UI translation.

Answer 3

http://www.qianqin.de/qtranslate/

is what you need ...

Edit I - after comment. First - thanks for all who contributed in the downvotes torrent. (this is what happens when one does not visit frequently enough :- ) )

now - The function that handles the switch is in qtranslate-core. (starts at line 80 more or less - depends on the version that you want.)

Since you can not look into a NOT OOP code , and I am now with nothing else to do - I took 10 minutes to synthesize , paraphrase compile that non-OOp with yet another non-OOP code for you .

(sorry, - primitive old skool here)

Assuming that I understood the question && Assuming you want the code to be for admin && assuming you will know how to port it to front end if you want && assuming you understand that the code is not optimal :

<?php
/*
Plugin Name: k99 language switcher
Plugin URI: http://www.krembo99.com
Description: Admin Language switcher proof of concept only - do not use in production.
Version: 0.0.0.0.0.0.0.1
Author: Krembo99
Author URI: http://www.krembo99.com
*/ 
?>
<?php function k99_add_language_menu() {
    //  k99_load_ajax_display_functions();
?>  
    <div class="mgmb_help_setting">
    <?php _e('Language:','your_text_domain'); ?>
    <select name="mgmb_language_setting_help" id="mgmb_language_setting_help" onChange="mgmb_set_language_cookies(this.value);" >
        <option value="en_US" <?php if($_COOKIE['k99_userLang']=="en_US"){echo "selected";} ?>><?php _e('English','your_text_domain');?></option>
        <option value="de_DE" <?php if($_COOKIE['k99_userLang']=="de_DE"){echo "selected";} ?>><?php _e('German','your_text_domain');?></option>
        <option value="zh_CN" <?php if($_COOKIE['k99_userLang']=="zh_CN"){echo "selected";} ?>><?php _e('Chinese','your_text_domain');?></option>
    </select>
    </div>
<?php   
}
// Now we set that function up to execute when the help action is called
add_filter('contextual_help', 'k99_add_language_menu');

// I guess this is your mysterious "browser stuff"
function k99_language_change($lang){ 
 global $locale;
 // wp_cache_set( "language", $lang, 'options' );
    if ( isset($_COOKIE['k99_userLang'])) {
      $lang = $_COOKIE['k99_userLang'];
    }
    define( 'WPLANG', $lang );
 if($locale!= $lang) {
    $locale = $lang;
    load_plugin_textdomain('your_text_domain', false, dirname( plugin_basename(__FILE__) ) . '/lang'); // sample use for plugins textdomain
    load_plugin_textdomain('your_text_domain2', false, dirname( plugin_basename(__FILE__) ) . '/lang');
    load_plugin_textdomain('your_text_domain3', false, dirname( plugin_basename(__FILE__) ) . '/lang');
 }
  return $locale;
}
add_filter('locale', 'k99_language_change',99);

////////// +++++++++++++++  START COOKIES CREATION +++++++++++++++//////////////////
// Javascript function set the language cookies
// access external
// @param lang - language code
// @return NULL
// or maybe this is the OP´s mysterious "browser stuff" ??
    function mgmb_print_script() {
    ?>
    <script type="text/javascript" >
    function mgmb_set_language_cookies(lang){   
        var Then = new Date(); 
        Then.setTime(Then.getTime() + 10000*60*60*1000 ); //set cookie expire to 10000 hours cookies (hour*minute*seconds*1000)
        document.cookie = "k99_userLang="+lang+";expires="+ Then.toGMTString();
        window.location.reload();
        } 
        </script>
<?php
} 
add_action('admin_print_scripts', 'mgmb_print_script');  // this is not the right way to do .. but no time now.
?>

REMARKS :

1 - This was built in 10 min. on local machine while at the airport . The reason why I say this is that the only ready available wordpress installation that I have here is quite old . (2.9 I think).

This means that probably the language menu will appear UNDER the contextual help div, due to the fact that a new div structure was recently introduced (with tabs) - but still it should work. (I promise to get back to this later if I have time)

If I had more time (and a new wordpress code here ) i would probably integrate this in the new admin-bar with add_action( 'admin_bar_menu', 'k99_add_language_menu_2', 1000 ); (I already promised to get back to this)

2 - you should have the listed languages files inside the "languages" folder in wp-content (better??) or wp-include. regarding this point - the code is only a proof of concept - and of course if one has more time the menu should be built in a dynamic way and not like done here.

3 - your WPLANG in config should be empty. I am not sure it will work on newer wp versions if a language is already set.

4 - it is a simple synthesized and paraphrased proof of concept built on what was seen in qtranslate code (also old version) - so most of the things are done the "quick" way, not necessarily the "right" way (like adding JS, no dedicated textdomain etc..).

EDIT II

someone is lucky today ! (Flight Delay )

Since you were looking for "ideas" for approaches , here is another famous one .

It will not fit in a plugin, or actually any other non-exclusive environment , but it might give you another direction as how to handle the "Browser stuff".

This will allow one to get the language with a GET like : <a href="index.php?lang=de">German</a> or <a href="whatever.php?lang=ml">my Language</a>

To use , you can create a code (let´s call it wp-langswitch.php )

 session_start();
 if ( isset( $_GET['lang'] ) ) {
    $_SESSION['WPLANG'] = $_GET['lang'];
    define ('WPLANG', $_SESSION[WPLANG]);
 } else {
    if(isset($_SESSION['WPLANG'])) {
        define ('WPLANG', $_SESSION['WPLANG']);
        $_GET['lang'] = $_SESSION['WPLANG'];
    } else {
        if ( isset( $_SERVER["HTTP_ACCEPT_LANGUAGE"] ) ) {
            $languages = strtolower( $_SERVER["HTTP_ACCEPT_LANGUAGE"] );
             $languages = explode( ",", $languages );
            $_SESSION['WPLANG'] = $languages[0];
            $_SESSION['WPLANG'] = str_replace("-", "_", $_SESSION['WPLANG']);
            $_GET['lang'] = substr($_SESSION['WPLANG'],0,2);
            define ('WPLANG', $_SESSION[WPLANG]);
        } else {
            define ('WPLANG', '');
        }
    }
 }

now, in wp-config, just before the WPLANG constant , we need to include our code .

 require_once(dirname(__FILE__).'/wp-langswitch.php');
 define ('WPLANG', ''); 

Now - obviously it would be better to add some cookies to the mix to store the languages .

EDIT III

I promised to get back to this later - here is how (in a very non-correct and primitive way ) it could be integrated inside the admin-bar (instead of the contextual-help-menu)

 function k99_add_language_menu_bar() {
    global $wp_admin_bar, $wpdb;
    if ( !is_super_admin() || !is_admin_bar_showing() )
        return;
// I am sure you can find a way alone to construct array from reading folder . If not , comment and I will update again.

if($_COOKIE['k99_userLang']=="en_US"){$sel==$_COOKIE['k99_userLang'];} 
if($_COOKIE['k99_userLang']=="de_DE"){$sel==$_COOKIE['k99_userLang'];}
if($_COOKIE['k99_userLang']=="zh_CN"){$sel==$_COOKIE['k99_userLang'];}

    $k99_lang = '';
    $k99_lang .= '<select name="mgmb_language_setting_help" id="mgmb_language_setting_help" onChange="mgmb_set_language_cookies(this.value);" >';
    $k99_lang .= '<option value="en_US" >English</option>';
    $k99_lang .= '<option value="de_DE" >German</option>';
    $k99_lang .= '<option value="zh_CN" >Chinese</option></select>';

    /* Add the main siteadmin menu item */
    $wp_admin_bar->add_menu( array( 'id' => 'Language', 'title' => __( 'language', 'your_text_domain3' ), 'href' => FALSE ) );
    $wp_admin_bar->add_menu( array( 'parent' => 'Language', 'title' => $k99_lang, 'href' => FALSE ) );
}
add_action( 'admin_bar_menu', 'k99_add_language_menu_bar', 999 );

Just replace this function (or add) to the old code (the original NON - OOP non-plugin) .

Like I said, I do not have a new wordpress installation here on local that features admin-bar - but it should work .

(and then again, it might not work...but I am sure you could fix that if you really want - even thought it is not OOP ) :-)

gotta run now . hope it helps somehow.

EDIT IV - changed edit III to working verion for admin menu bar (at least on my wp 3.4)

since I had no working install of 3.4 - and now I returned and I do - I have edited the Edit III solution - and it works for me .

About the upvotes, I could not care less . And I do not need any "bounties" (whatever those may be..) It was just for the sake of the exercise you shlould maybe give it to the author of qTranslate . :-) despite of the fact that it is not OOP - it is a genious plugin with a lot to learn from in a lot of areas . considering the "when" of this plugin release , it is even amazing. worth the indescribably effort of reading a NON OOP code - even if it is not - OOP . And even if it is not correctly indented (good god !).