_getting-pages-by-slugs.md

Get Parent/Child/Ancestor Pages by ID or Slug

• get_id_by_slug.php
• is_child.php
• is_tree.php

example usage: examples.php

examples.php

<?php 
  if ( is_tree( 'subpage' ) ) { // Using the slug /subpage/, but you could also use the ID of /subpage/
    // [[... insert your code here ...]]
  }
  if ( is_child('subjects') ) {
    //do something
  }
  $page_id = get_id_by_slug('resources');
?>

get_id_by_slug.php

<?php
/**
 * Get a Page's ID by slug
 * http://erikt.tumblr.com/post/278953342/get-a-wordpress-page-id-with-the-slug
 */
function get_id_by_slug($page_slug) {
  $page = get_page_by_path($page_slug);
  if ($page) {
      return $page->ID;
  } else {
      return null;
  }
}
?>

is_child.php

<?php
/**
 * BEGIN: Check If Page Is Child
 * Source: http://bavotasan.com/2011/is_child-conditional-function-for-wordpress/
 */
function is_child( $page_id_or_slug ) { // $page_id_or_slug = The ID of the page we're looking for pages underneath
  global $post; // load details about this page

  if ( !is_numeric( $page_id_or_slug ) ) { // Used this code to change a slug to an ID, but had to change is_int to is_numeric for it to work.
    $page = get_page_by_path( $page_id_or_slug );

    if (isset($page)) {
      $page_id_or_slug = $page->ID;
      if ( is_page() && ( $post->post_parent == $page_id_or_slug ) )
        return true; // we're at the page or at a sub page
      else
        return false; // we're elsewhere
    } else {
      return false;
    }
  }
};

?>

is_tree.php

<?php
/**
 * Check If Page Is Parent/Child/Ancestor
 * Source: http://css-tricks.com/snippets/wordpress/if-page-is-parent-or-child/#comment-172337
 */
function is_tree( $page_id_or_slug ) { // $page_id_or_slug = The ID of the page we're looking for pages underneath
  global $post; // load details about this page

  if ( !is_numeric( $page_id_or_slug ) ) { // Used this code to change a slug to an ID, but had to change is_int to is_numeric for it to work: http://bavotasan.com/2011/is_child-conditional-function-for-wordpress/
    $page = get_page_by_path( $page_id_or_slug );
    $page_id_or_slug = $page->ID;
  }

  if ( is_page() && ( $post->post_parent == $page_id_or_slug || (is_page( $page_id_or_slug ) || in_array($page_id_or_slug, $post->ancestors) ) ) )
    return true; // we're at the page or at a sub page
  else
    return false; // we're elsewhere
};