Adding a Notification to Old WordPress Posts

While some articles may be timeless, depending on the type of content being published, many posts have a definite expiry date. It is the double edged sword of rapidly evolving technologies – they improve swiftly, but articles written about them become outdated just as fast. This site, for instance, is primarily about cloud computing and servers – as such, many of the posts, from even a few months ago, may no longer be applicable.

When searching for technology related articles, I usually restrict the search to the past year. Articles without a date are simply annoying, and those where the date is in some obscure location aren’t much better.

A common approach to dealing with outdated posts is to add a notice to them. The idea being that there is likely some useful information in them, despite their age, but that readers should be aware that the post was from some time ago and some things may have changed in the interim.

I’d suggest there are (at least) three ways of accomplishing the above:

1. Manually edit posts
• When you feel that a post merits such a notice, add one in. This may be a good approach if there are only one or two posts that actually need it. For any site that generates more than a few of these, a more automated approach would be better.
2. Edit your theme.
• This seems to be the commonly proposed solution, add a few lines of code to the theme to display the notification. It is quite easy to implement, although, it may take a few moments to find the right file. The problem is that any updates to the theme will overwrite your modifications. Arguably, the solution may lie in the form of a child theme, but really, you only want to be modifying a small part of an existing function, and not completely replacing that function. This site uses a child theme with Twenty Eleven, and I added the following to content-single.php, immediately preceding <div class="entry-content">:

  diff($ref);
  	$interval = "";
  	if ($diff->y){$interval .= $diff->y . " year" . ($diff->y == 1?"":"s");}
  	if ($diff->m){$interval .= ($interval?", ":"") . $diff->m . " month" . ($diff->m == 1?"":"s");} ?>
  
  	
  
  		This article was published  ago. Due to the rapidly evolving world of technology, some concepts may no longer be applicable.
  	
  

3. Use a plugin. This would be the way to go – it will withstand updates, and offer a degree of customization – without having to hardcode values into your theme. The problem is, it is rather difficult to come across such a plugin. At least one, however exists – Old Posts Notifier. However, it was written for the 2.x versions of WordPress, hasn’t been updated in over 2 years, and has a bit of undesired tracking included in it.

I had a bit of spare time earlier in the week, so I extracted my in-line modifications into a plugin – ‘Aged Posts’, and added a few things to make it more useable. Essentially, I wanted to be able to:

• Change the displayed text and style from a settings page
• Change the post age limit for displaying the notification.
• Exclude individual posts from displaying the notification.

The result is fairly simple – it doesn’t have a lot of options, but it is functional. The plugin saves the style to a css file – which allows it to be included in any minification performed.

• Note: This plugin requires PHP > 5.3, since it uses DateTime::diff().
• Tested with WordPress 3.2 and 3.3, with the TwentyTen and TwentyEleven themes.
• This plugin is NOT internationalized – I might get around to if people find it useful.Likewise, I haven’t yet posted on WordPress’ plugins site, but may do so in the future.
  • Update (Oct 9, 2012): Added some form of i18n to the plugin at the prompting of ‘giacomo’ (commenter, below) – might be a bit rough (and is somewhat untested), but it appears to work.

  Undoubtedly there are some non-standard code practices used (it is my first WordPress plugin), but hopefully nothing of major concern.

  If you find a bug, have an improvement or suggestion, or simply found it useful, please let me know.

  Translations

  If you are using the i18n version, translations are supported through the use of PO/MO files. You can add PO/MO files to the plugin’s languages folder, or under WP_LANG_DIR/agedposts/ (which will be used in preference to the plugin’s language folder). Using a directory external to the plugin’s own directory allows for upgrades to not overwrite custom translations.

  Italian (courtesy of Giacomo)

  The Code

  Download (no i18n): agedposts.zip [39.2kB, MD5: 683B0D1F79C7ABA2749F3233EA6F8D7B])
  Download (with i18n): agedposts-i18n [43.8kB, MD5: 7780659593F181626CCDCFDCC9558053])

   3,
  				$prefix . 'age_units' => 'months',
  				$prefix . 'priority' => 20,
  				$prefix . 'display_text' => 'This post was published @@INTERVAL@@ ago. Some material it contains may no longer be applicable.'
  			);
  			
  			foreach ($default_options as $option_name => $option_value) {
  				if (get_option($option_name) === FALSE) {
  					add_option($option_name, $option_value, '', 'no');
  				}
  			}
  			
  			$agedposts_style = get_option($prefix . 'style');
  			if ($agedposts_style === FALSE) {
  				$agedposts_style = file_get_contents(plugin_dir_path(__FILE__) . "style.css.orig");
  				add_option($prefix . 'style', $agedposts_style, '', 'no');
  			}
  			file_put_contents(plugin_dir_path(__FILE__) . "style.css", $agedposts_style);
  		}
  		function main()
  		{
  			if (is_single()) {
  				if (get_post_meta(get_the_ID(), $this->prefix . 'include', true) !== '0') {
  					$priority       = get_option($this->prefix . 'priority');
  					$timestamp      = get_the_time('U');
  					$age            = intval(get_option($this->prefix . 'age'));
  					$age_units      = get_option($this->prefix . 'age_units');
  					$this->interval = "$age $age_units ago";
  					if ($timestamp < strtotime($this->interval)) {
  						add_filter('the_content', array(&$this,	'display'), $priority);
  						add_action('wp_enqueue_scripts', array(&$this,'add_stylesheet'));
  						$now  = new DateTime();
  						//Todo: Add PHP 5.2 compatibility
  						$diff = $now->diff(new DateTime('@' . $timestamp));
  						if ($diff->y) {
  							$this->disp_interval .= $diff->y . " year" . ($diff->y == 1 ? "" : "s");
  						}
  						if ($diff->m) {
  							$this->disp_interval .= ($this->disp_interval ? ", " : "") . $diff->m . " month" . ($diff->m == 1 ? "" : "s");
  						}
  					}
  				}
  			}
  		}
  		function display($content)
  		{
  			$display_text = get_option($this->prefix . 'display_text');
  			$content      = '
  ' . str_replace("@@INTERVAL@@", $this->disp_interval, $display_text) . '
  ' . $content;
  			return $content;
  		}
  		function add_stylesheet()
  		{
  			wp_register_style($this->prefix . 'style', plugins_url('style.css', __FILE__));
  			wp_enqueue_style($this->prefix . 'style');
  		}
  		function add_ap_meta_box()
  		{
  			add_meta_box($this->prefix . 'meta', __('Aged Posts'), array(&$this,'render_meta_box_content'), 'post', 'side');
  		}
  		function render_meta_box_content($post)
  		{
  			wp_nonce_field(plugin_basename(__FILE__), $this->prefix . 'nonce');
  			echo 'ID, $this->prefix .'include', true) === '0' ? '' : 'checked') . '/> Display "old post" notice';
  		}
  		function meta_save($post_id)
  		{
  			if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
  				return;
  			}
  			if (!wp_verify_nonce($_POST[$this->prefix . 'nonce'], plugin_basename(__FILE__))) {
  				return;
  			}
  			if ('page' == $_POST['post_type']) {
  				if (!current_user_can('edit_page', $post_id)) {
  					return;
  				}
  			} else {
  				if (!current_user_can('edit_post', $post_id)) {
  					return;
  				}
  			}
  			$agedposts_include = ($_POST[$this->prefix . 'include'] ? 1 : 0);
  			if (!add_post_meta($post_id, $this->prefix . 'include', $agedposts_include, true)) {
  				update_post_meta($post_id, $this->prefix . 'include', $agedposts_include);
  			}
  		}
  		function admin_menu()
  		{
  			add_options_page('Aged Posts Options', 'Aged Posts', 'manage_options', $this->prefix , array(&$this,'admin_options'));
  			add_action('add_meta_boxes', array(&$this,'add_ap_meta_box'));
  		}
  		function admin_options()
  		{
  			if (!current_user_can('manage_options')) {
  				wp_die(__('You do not have sufficient permissions to access this page.'));
  			}
  			
  			if (isset($_POST[$this->prefix . 'submit'])) {
  				update_option($this->prefix . 'age', $_POST[$this->prefix . 'age']);
  				update_option($this->prefix . 'age_units', $_POST[$this->prefix . 'age_units']);
  				update_option($this->prefix . 'priority', $_POST[$this->prefix . 'priority']);
  				update_option($this->prefix . 'display_text', $_POST[$this->prefix . 'display_text']);
  				update_option($this->prefix . 'style', $_POST[$this->prefix . 'style']);
  				if(file_put_contents(plugin_dir_path(__FILE__) . "style.css", $_POST[$this->prefix . 'style'])===FALSE){
  					?>
  Unable to write stylesheet. Please manually update 
  Settings saved.
  
  			  
  
  				
  Aged Posts Options
  				
  Post Age
  				
  Display notice on posts older than:
  				  
  				  
  					>Weeks
  					>Months
  					>Years
  				  
  				
  				
  Priority
  					
  The priority is used, by WordPress, to determine the order in which filter functions are run. Lower values result in later execution. The default for most filters is 10; the default for this plugin is 20. Only change this value if you find other plugins are conflicting with this one.
  					
  Priority:   
  				
  Text to Display
  				
  Text to display (@@INTERVAL@@ will be replaced with the number of months/years):
  
  				  <?php 
  					echo get_option($this->prefix . 'display_text'); 
  				  ?>
  				
  				
  Appearance
  				
  The following is the CSS class definition will be used to style the display. It has been loaded from the database, and will be saved to a file.:
  
  				  <?php
  					echo get_option($this->prefix . 'style'); 
  				  ?>
  				
  				
  
  				
  
  				  
  				
  			  
  			
  

  Download (no i18n): agedposts.zip [39.2kB, MD5: 683B0D1F79C7ABA2749F3233EA6F8D7B])
  Download (with i18n): agedposts-i18n [43.8kB, MD5: 7780659593F181626CCDCFDCC9558053])