WordPress Plugin: Sub Page Functions

Plugin Name: Sub Page Functions
Current Version: 1.0
Release: 10 March 2007
Download: sub_page_functions.zip

I use WordPress throughout my site to organize content. In particular, I’ve found that WordPress “pages” are useful posting the short stories that I’ve written and that I’ve released under Creative Commons licenses. I wanted a particular sidebar to show up on the pages that are stories, and I immediately thought that if I made these stories a subpage of my “Published Stories” page, I could do that easily with a “is_subpage” conditional tag. Unfortunately, there is no such tag built in to WordPress. After experimenting with a few different ideas, I finally decided to create my own tags and create a plugin. “Sub Page Functions” is that plugin.

About the Plugin

Sub Page Functions introduces two new tags to use in WordPress templates. The first is a conditional tag which returns a boolean result; the second returns an object containing information about a subpage’s parent page.

This plugin has been tested with WordPress versions 2.1 through 2.3, and should work with most other versions.

rsc_is_subpage([$parent_page_id])

This function determines whether the current page is a subpage or not. The parameter $parent_page_id is optional; if it is passed, then the function determines whether the current page is a subpage of the parent page with the given ID.

Examples:

< ?php if (rsc_is_subpage()) echo 'This is a subpage!'; ?>

This simply prints the phrase “This is a subpage!” if the page displayed is indeed a subpage.

< ?php
if (rsc_is_subpage(167)) {
echo 'This is a subpage of page 167!';
} else {
echo 'This is not a subpage of page 167!';
?>

In my own site, I use this function to include a different sidebar for subpages of my “Published Stories” page:

< ?php
if (rsc_is_subpage(167)) {
include ("story_sidebar.php");
} else {
include ("other_sidebar.php");
}
?>

rsc_get_parent()

This function returns a $post object containing information about the current page’s parent page, if any. If there is no parent page, the function returns false.

Example:

< ?php
if ($parent = rsc_get_parent()) {
echo "The parent page is $parent->post_title";
} else {
echo 'There is no parent page';
}
?>

Installation

To install this plugin, unzip the .zip file and upload the file sub_page_functions.php to the wp-content/plugins subdirectory of your WordPress installation. Then go to the Plugins page in your Admin screen, and activate the plugin there. That’s it!