wordpress subpage tag

Question

I'm building a wordpress theme right now and I'm using conditionals in the sidebar to display different information for each page like so:

if (is_page('services')) {
 etc.....
} elseif (etc....

However, some of the subpages do not have their own specific conditional. How can I make it so that a conditional for a parent page applies to its subpages as well?

Thanks!

Answer 1

You could do this a number of ways. There might be an easier way, but this is what I would do: On the page itself, check if it is a child page:

     if ( is_page() && $post->post_parent ) 
     {
          // This is a subpage
          return true;

     } 
     else 
     {
         // This is not a subpage
         return false;
     }

which will check if the page is a child, in which case you can fetch the conditional from the parent the same way you are currently, except specify the parent instead of the current page when checking.

Answer 2

You can also put this snippet of code in your functions.php file and use it anywhere on your wp code.

    function is_subpage() {
    global $post;                                 // load details about this page
        if ( is_page() && $post->post_parent ) {      // test to see if the page has a parent
               $parentID = $post->post_parent;        // the ID of the parent is this
               return $parentID;                      // return the ID
        } else {                                      // there is no parent so...
               return false;                          // ...the answer to the question is false
        };
};

Source: http://codex.wordpress.org/Conditional_Tags