Creating virtual pages on Wordpress.

functions.php

// Class to create virtual pages
// http://davejesch.com/2012/12/creating-virtual-pages-in-wordpress/
if (!class_exists('DJVirtualPage')) {
	class DJVirtualPage {
		private $slug = NULL;
		private $title = NULL;
		private $content = NULL;
		private $author = NULL;
		private $date = NULL;
		private $type = NULL;
 
		public function __construct($args) {
			if (!isset($args['slug']))
				throw new Exception('No slug given for virtual page');
 
			$this->slug = $args['slug'];
			$this->title = isset($args['title']) ? $args['title'] : '';
			$this->content = isset($args['content']) ? $args['content'] : '';
			$this->author = isset($args['author']) ? $args['author'] : 1;
			$this->date = isset($args['date']) ? $args['date'] : current_time('mysql');
			$this->dategmt = isset($args['date']) ? $args['date'] : current_time('mysql', 1);
			$this->type = isset($args['type']) ? $args['type'] : 'page';
 
			add_filter('the_posts', array(&$this, 'virtualPage'));
		}
 
		// filter to create virtual page content
		public function virtualPage($posts) {
			global $wp, $wp_query;
 
			if (count($posts) == 0 &&
				(strcasecmp($wp->request, $this->slug) == 0 || $wp->query_vars['page_id'] == $this->slug)) {
				//create a fake post intance
				$post = new stdClass;
				// fill properties of $post with everything a page in the database would have
				$post->ID = -1;                          // use an illegal value for page ID
				$post->post_author = $this->author;       // post author id
				$post->post_date = $this->date;           // date of post
				$post->post_date_gmt = $this->dategmt;
				$post->post_content = $this->content;
				$post->post_title = $this->title;
				$post->post_excerpt = '';
				$post->post_status = 'publish';
				$post->comment_status = 'closed';        // mark as closed for comments, since page doesn't exist
				$post->ping_status = 'closed';           // mark as closed for pings, since page doesn't exist
				$post->post_password = '';               // no password
				$post->post_name = $this->slug;
				$post->to_ping = '';
				$post->pinged = '';
				$post->modified = $post->post_date;
				$post->modified_gmt = $post->post_date_gmt;
				$post->post_content_filtered = '';
				$post->post_parent = 0;
				$post->guid = get_home_url('/' . $this->slug);
				$post->menu_order = 0;
				$post->post_tyle = $this->type;
				$post->post_mime_type = '';
				$post->comment_count = 0;
 
				// set filter results
				$posts = array($post);
 
				// reset wp_query properties to simulate a found page
				$wp_query->is_page = TRUE;
				$wp_query->is_singular = TRUE;
				$wp_query->is_home = FALSE;
				$wp_query->is_archive = FALSE;
				$wp_query->is_category = FALSE;
				unset($wp_query->query['error']);
				$wp_query->query_vars['error'] = '';
				$wp_query->is_404 = FALSE;
			}
			return ($posts);
		}
	}
}

// Create virtual "Blog" page
function virtual_pages() {
	$url = trim(parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH), '/');

	// Passing parameters to virtualisation class
	if ($url == 'blog') {
        new DJVirtualPage(array(
			'slug'	=> $url,
			'type'	=> 'page',
			'title'	=> 'Blog'
		));
	}
	
	// Overriding template
	function override_default_template($template) {
		if (is_page('blog')) {
			$newTemplate = locate_template(array('page-blog.php'));
			if ($newTemplate != '') {
				return $newTemplate;
			}
		}
		return $template;
	}	
}
add_action('init', 'virtual_pages');
add_filter('template_include', 'override_default_template', 99);