[Plugin: Polylang] Language switching from a Post

It would be easier to do this if there was a function in API to get list of all languages.

Well, I did the work for you so you can put this code in your theme functions.php
If you decide to make a plugin from this code, wrap it in plugins_loaded hook.

if(class_exists('Polylang_Base') && !function_exists('pll_languages_list')){

	/**
	 * Gets list of Polylang languages
	 * @param boolean $hide_empty Optional, default is to return all language taxonomies.
	 * @return array Array of language taxonomy term objects
	 */
	function pll_languages_list($hide_empty = FALSE){
		global $polylang;
		$langs = array();
		if( $polylang instanceof Polylang_Base ){
			$langs = (array)$polylang -> get_languages_list($hide_empty);
		}
		return $langs;
	}

	/**
	 * Template tag to display other languages of a post
	 * @param int $post_id Optional post ID, defaults to current post in the loop
	 * @param array $args Optional arguments list
	 */
	function pll_the_post_translations($post_id = NULL, $args = array()){
		global $post;
		$defaults = array(
			'sep' => "\n",
			'before' => '<ol class="translations">',
			'after' => '</ol>',
			'echo' => TRUE,
		);
		$args = wp_parse_args($args, $defaults);
		extract($args, EXTR_SKIP);

		$the_post = ($post_id !== NULL)? get_post($post_id) : $post;
		$languages = pll_languages_list();
		$current_lang = pll_current_language();

		$output = ''; $outarr = array();
		if($languages && isset($the_post->ID)){
			foreach($languages as $lang){
				$translated_id = (int)pll_get_post($the_post->ID, $lang->slug);
				if(!$translated_id && $current_lang != $lang->slug){
					continue;
				}
				$tranlated_link = get_permalink($translated_id);
				$class = ($current_lang == $lang->slug) ? 'current' : '';
				$outarr[] = '<li class="'.$class.'"><a href="'.esc_url($tranlated_link).'" hreflang="'.esc_attr($lang->slug).'">'.$lang->name.'</a></li>';
			}
			$output = implode($sep, $outarr);
		}
		if(!$echo)
			return $output;
		 echo $output;
	}
}

You can use it in your theme like this:

<div class="translations-list">
	<?php
	if(function_exists('pll_the_post_translations'))
		pll_the_post_translations();
	?>
</div>

Now, where is my coffee?

I just edited the code in my previous post. I had left out one logical step to check if there is no translation and had left the debug code in.

Copy it again and add in functions.php before closing ?> line

Just look for missing semicolon ; at the end of line before the code you pasted.
That or make the code into a plugin.
Create a new file in plugins directory named pll-posttranslations.php with following content:

<?php
/*
Plugin name: Polylang Post Translations
Version: 0.1
Description: Adds functions for displaying available translatins of a post
Author: AndyDeGroo
*/

add_action('plugins_loaded','pllpt_add_functions',1000);
function pllpt_add_functions(){

//[the code hoes here]

}
?>

replace //[the code hoes here] part with the code and activate the plugin.

Sorry, that function was introduced around 0.8.0.6 development release.

You can download the latest dev release from http://downloads.wordpress.org/plugin/polylang.zip
Note: some things may have changed and it may not be entirely stable.

Another option would be to add the function right after if(class_exists('Polylang_Base') && !function_exists('pll_languages_list')){ statement in the first code block:

if(!function_exists('pll_current_language')){
		/**
		 * Polylang current languages
		 * backcompat for versions before Polylang 0.8.0.6
		 * @param string $args Optional, what to return, locale or slug. Defaults to slug.
		 * @return string|array Array of language taxonomy term objects
		 */
		function pll_current_language($args = 'slug') {
			global $polylang;
			if(method_exists($polylang, 'current_language')){
				return isset($polylang) ? $polylang->current_language($args) : false;
			}else{
				$curlang = $polylang->get_current_language();
				return ( empty($curlang) || !isset($curlang->name) ) ? false :
				$args == 'name' ? $curlang->name :
				$args == 'locale' ? $curlang->description :
				$curlang->slug;
			}
		}
	}

I tested it and it works.

EDIT: There is another function missing in 0.8 which is needed by this code. I could implement it, but it is easier to download development version.

I’ll quote myself:

I just edited the code in my previous post. I had left out one logical step to check if there is no translation and had left the debug code in.

I fixed it in original entry instead of posting new.

The following code (the long one that I paste in the end of this message, and that is meant to be put in the end of the functions.php of your current theme) adapts the one by AndyDeGroo.
It is still called by a

<div class="translations-list">
	<?php
	if(function_exists('pll_the_post_translations'))
		pll_the_post_translations();
	?>
</div>

that you put where you need it in your theme (ex, page.php, archives.php, etc).

It lists the available translations of the current posts.

Put
$this->register_string('others', 'others');
just after the code

$this->register_string(__('Site Title'), get_option('blogname'));
$this->register_string(__('Tagline'), get_option('blogdescription'));
$this->register_string(__('Date Format'), get_option('date_format'));
$this->register_string(__('Time Format'), get_option('time_format'));

in the file plugins/polylang/include/admin.php

–> It displays a text before the result, a text that is editable 🙂 in the settings of Polylang (Dashboard / Settings / Languages / Strings translation).

if(class_exists('Polylang_Base') && !function_exists('pll_languages_list')){

	/**
	 * Gets list of Polylang languages
	 * @param boolean $hide_empty Optional, default is to return all language taxonomies.
	 * @return array Array of language taxonomy term objects
	 */
	function pll_languages_list($hide_empty = FALSE){
		global $polylang;
		$langs = array();
		if( $polylang instanceof Polylang_Base ){
			$langs = (array)$polylang -> get_languages_list($hide_empty);
		}
		return $langs;
	}

	/**
	 * Template tag to display other languages of a post
	 * @param int $post_id Optional post ID, defaults to current post in the loop
	 * @param array $args Optional arguments list
	 */
	function pll_the_post_translations($post_id = NULL, $args = array()){
		global $post;
		$defaults = array(
			'sep' => "\n",
			'before' => pll__('others').':<br/><ul class="translations">',
			'after' => '</ul>',
			'echo' => TRUE,
		);
		$args = wp_parse_args($args, $defaults);
		extract($args, EXTR_SKIP);

		$the_post = ($post_id !== NULL)? get_post($post_id) : $post;
		$languages = pll_languages_list();
		$current_lang = pll_current_language();

		$output = ''; $outarr = array();
		if($languages && isset($the_post->ID)){
			foreach($languages as $lang){
				$translated_id = (int)pll_get_post($the_post->ID, $lang->slug);
				if(!$translated_id || $current_lang == $lang->slug){
					continue;
				}
				$tranlated_link = get_permalink($translated_id);
				$class = ($current_lang == $lang->slug) ? 'current' : '';
				$outarr[] = '<li class="'.$class.'"><a href="'.esc_url($tranlated_link).'" hreflang="'.esc_attr($lang->slug).'">'.esc_html(get_the_title($translated_id)).' ('.$lang->name.')</a></li>';
			}
			if (count($outarr)) {
$output = $before . implode($sep, $outarr) . $after;
}
		}
		if(!$echo)
			return $output;
		 echo $output;
	}
}

?>

Hope it works for you!
Don’t thank me, it’s a friend of mine who did the modifications.