Synchronize a menu with your page hierarchy

WordPress’s menu feature is a fantastic way of creating a hierarchical menu, but unfortunately you still have to keep your pages in their own, separate hierarchy, using a horribly cumbersome interface, or a special plugin. The code snippet below will adjust your page hierarchy to match your menu, every time you edit your menu (so long as javascript is turned on). It does this by changing post_parent and menu_order for any pages that are no longer in sync with the menu. Pages that are not in the menu are not changed. To use the function in your own plugin, on the first line, you’ll need to enter the id of the menu you want to keep in sync.

The function gets the details of the menu by calling get_term_by, whilst wp_get_nav_menu_items returns all of the items in the menu. Finally, wp_update_post modifies any pages that need to be changed.

add_action ('wp_update_nav_menu', 'emw_create_hierarchy_from_menu', 10, 2);

function emw_create_hierarchy_from_menu($menu_id, $menu_data = NULL) {
	if ($menu_id != 1)  // You should update this integer to the id of the menu you want to keep in sync
	if ($menu_data !== NULL) // If $menu_date !== NULL, this means the action was fired in nav-menu.php, BEFORE the menu items have been updated, and we should ignore it.
	$menu_details = get_term_by('id', $menu_id, 'nav_menu');
	if ($items = wp_get_nav_menu_items ($menu_details->term_id)) {
	    // Create an index of menu item IDs, so we can find parents easily
		foreach ($items as $key => $item)
    		$item_index[$item->ID] = $key;
    	// Loop through each menu item
		foreach ($items as $item)
			// Only proceed if we're dealing with a page
			if ($item->object == 'page') {
				// Get the details of the page
				$post = get_post($item->object_id, ARRAY_A);
				if ($item->menu_item_parent != 0)
					// This is not top-level menu items, so we need to find the parent page
					if ($items[$item_index[$item->menu_item_parent]]->object != 'page') {
						// The parent isn't a page. Queue an error message.
						global $messages;
						$messages[] = '<div id="message" class="error"><p>' . sprintf( __("The parent of <strong>%1s</strong> is <strong>%2s</strong>, which is not a page, which means that this part of the menu cannot sync with your page hierarchy.", ETTD), $item->title, $items[$item_index[$item->menu_item_parent]]->title) . '</p></div>';
						$new_post['post_parent'] = new WP_Error;
					} else
						// Get the new parent page from the index
						$new_post['post_parent'] = $items[$item_index[$item->menu_item_parent]]->object_id;
					$new_post['post_parent'] = 0; // Top-level menu item, so the new parent page is 0
				if (!is_wp_error ($new_post['post_parent'])) {
					$new_post['ID'] = $post['ID'];
					$new_post['menu_order'] = $item->menu_order;
					if ($new_post['menu_order'] !== $post['menu_order'] || $new_post['post_parent'] !== $post['post_parent'])
						// Only update the page if something has changed
						wp_update_post ($new_post);

Automatically add Lorem Ipsum text to blank WordPress pages

If you’re creating a new WordPress theme, it can be helpful to have some filler text in your pages. The snippet below adds a few paragraphs of lorem ipsum text to any blank post or page by filtering the_content. The text is retrieved from the site, and is cached, site-wide, for one hour using the set_transient and get_transient functions.

add_filter ('the_content', 'emw_custom_filter_the_content');

* Returns Lorem Ipsum text for blank pages
* @param string $content - the page's current contents
* @return string
function emw_custom_filter_the_content ($content) {
	if ($content == '') {
		if ($c = get_transient ('lipsum'))
			return $c;
		$content = wp_remote_get ('');
		if (!is_wp_error($content)) {
			$content = json_decode (str_replace ("\n", '</p><p>', $content['body']));
			$content = '<p>'.$content->feed->lipsum.'</p>';
			set_transient ('lipsum', $content, 3600); // Cache the text for one hour
			return $content;
	} else
		return $content;

Changing the settings for Genesis Reponsive Slider to allow multiple slideshows

Out of the box, the Genesis Responsive Slider can only be used in one way on your site because it’s options are set in an options panel. However, you can hook in to every setting, to create different sliders on different pages (although this code will not allow you to have different sized slideshows on every page – we’ll cover that in a future post).

I hook to the ‘wp’ action, because that is late enough for you to be able to calculate what slideshow parameters you may want, but early enough that the slideshow won’t have been generated yet. The parameters are changed by filtering genesis_pre_get_option_*, and a very useful PHP function called create_function.

add_action ('wp', 'emw_change_slide_show');

function emw_change_slide_show() {
	$slide_show_vars = array(
		'slideshow_timer' => 8000,
		'slideshow_delay' => 1500,
		'slideshow_arrows' => 1,
		'slideshow_pager' => 0,
		'slideshow_loop' => 1,
		'slideshow_height' => 250,
		'slideshow_width' => 978,
		'slideshow_effect' => 'fade',
		'slideshow_title_show' => 1,
		'slideshow_excerpt_show' => 0,
		'slideshow_excerpt_width' => 30,
		'location_vertical' => 'bottom',
		'location_horizontal' => 'right',
		'slideshow_hide_mobile' => 1,
		'include_exclude' => 'include',
		'post_type' => 'page',
		'post_id' => '4, 7, 9'
	foreach ($slide_show_vars as $option => $value)
		add_filter ("genesis_pre_get_option_{$option}", create_function ('', "return '{$value}';"));

If you want to change the size of the slideshow, as we’ve done for this example, you’ll need a few additional lines (and you’ll need to re-generate WordPress thumbnails after you’ve made the change). Although the code on this page allows you to change the size of the slideshow from the default, you’ll need to have the same size on every page:

add_action ('wp', 'emw_change_slider_image_size');

function emw_change_slider_image_size() {
    add_image_size ('slider', 978, 250, true);

Finally, if you want to remove the Responsive Slider menu from the admin (because those settings are now overridden):

add_action ('init', 'emw_remove_responsive_slider_menu');

function emw_remove_responsive_slider_menu() {
	if (is_admin())
		remove_action('admin_menu', 'genesis_responsive_slider_settings_init', 15);

Caching a downloaded file

It’s often useful to download external files such as RSS feeds, Twitter feeds and so on. But you’ll also want those files cached, so that you’re not downloading them on every page view. Thankfully, WordPress provides two functions that make downloading and caching files very easy — wp_remote_get and set_transient.

The function below tries to act intelligently — the file will be cached for the time specified in $cache_time, which defaults to the time given by the ‘Cache-control’ header; and if the cache-control time is overridden, the ‘cache-control’ and ‘expires’ headers will be modified before being returned/cached, so that you can easily output the most appropriate headers if you need to.

* Downloads a URL, or returns it from the cache
* The function tries to act intelligently:
* 	(1) The file will be cached for the time specified in $cache_time, which defaults to the time given by the 'Cache-control:' header.
* 	(2) If cache-control time is overridden, the 'cache-control' and 'expires' headers will be modified before being returned/cached, so that you can easily output appropriate headers if you need to.
* @param string $url - the URL to be downloaded or returned
* @param integer $suggested_cache_time - the time to cache the file for (in seconds). If the time given by the 'Cache-control:' header is longer, this value will be overridden. If no time is provided by this variable or by the header, then the time will be set to 1 day
* @param boolean $also_return_headers
* @return mixed - if an error occurs, returns WP_ERROR. Otherwise, if $also_return_headers is true, returns an array with the keys 'body', 'headers', 'response' and 'cookies', otherwise returns the body as a string. See the documentation for wp_remote_get for examples.
function emw_get_cached_url ($url, $suggested_cache_time = 0, $also_return_headers = false) {
	$name = 'egcu-'.md5($url); // A short, unique name for the file to be cached
	// Return from the cache if possible
	if ($item = get_transient ($name)) {
		$v = unserialize(base64_decode($item));
		if ($also_return_headers)
			return unserialize(base64_decode($item));
			return $v['body'];
	} else {
		// Download the file
		$download = wp_remote_get ($url, array ('timeout' => 30, 'sslverify' => false));
		// Check for error
		if (is_wp_error ($download))
			return $download;
		else {
			// Calculate the cache time from the headers
			$actual_cache_time = $suggested_cache_time;
			if (isset($download['headers']['cache-control']) && ($start = strpos($download['headers']['cache-control'], 'max-age=')+8) !== FALSE) {
				$headers_cache_time = substr($download['headers']['cache-control'], $start);
				if (($a = strpos($headers_cache_time, ',')) !== FALSE)
					$headers_cache_time = substr($headers_cache_time, 0, $a);
				if ($headers_cache_time > $suggested_cache_time)
					$actual_cache_time = $headers_cache_time;
			// If no cache time is specified in the headers or the $suggested_cache_time variable, set the cache to 1 day
			if ($actual_cache_time == 0)
				$actual_cache_time = 86400;
			// Modify the headers to take account of the new cache time
			if (!isset($download['headers']['date']))
				$download['headers']['date'] = gmdate('D, d M Y H:i:s \G\M\T', $t = time());
			$download['headers']['cache-control'] = "public, max-age=".round($actual_cache_time*1.01);  // Multiplying by 1.01 ensures the browser will cache the file for slightly longer than the server. This ensures that by the time the browser requests the file again, it will have definitely been refreshed.
			$download['headers']['expires'] = gmdate('D, d M Y H:i:s \G\M\T', $t+(round($actual_cache_time*1.01)));
			// Cache the download
			set_transient ($name, base64_encode(serialize($download)), $actual_cache_time);
			// Return what was requested
			if ($also_return_headers)
				return $download;
				return $download['body'];

(The data is stored base64 encoded, because I’ve encountered bugs when simply storing it as serialised data.)