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Download: 'Is Child Of ' v.0.5

What does it do?

Ever wanted to find out with PHP and Wordpress whether a page is a subpage of another? Fair enough, that is easy to do,  using $post->post_parent. But what if you want to find out if a page is a subpage of a page two or more levels above it? That's where my plugin comes in. It's a function that will keep jumping up levels of the page hiearchy from the page it is called on until 1) it reaches the top without encountering the page you are looking for, returning false or 2) reaches the page you are looking, and therefore it returns true.

How does it work?

It's pretty simple, and take's two inputs, the second one which is optional. The first input is the id of the top page you are trying to see this is a child page of.  For example, take a look at this page structure, then the code below:

• Top Link One
• Top Link Two
  • Sub2 Link One
    • Sub2.1 Link One
      • Sub2.1.1 Link One
    • Sub2.1 Link Two
    • Sub2.1 Link Three
  • Sub2 Link Two
  • Sub2 Link Three
• Top Link Three
  • Sub3 Link One

// 'Top Link Two has the id 5

if(is_child_of(5))
{
// executes this code if you are on page or any child pages of 5
}

'Any child pages of 5′ would include all levels, even to the lowest level i.e. Sub2.1.1 Link One. Even on that, the above code will execute.

The other, optional input is actually the id of the page you are asking about. Now, normally, this is taken from the $post variable of the page that you are on by default, but if you any reason you want to know about a specific page, you put that page's id as the second parameter:

// Top page has to id of 5, and the page you want to know about has the id 10

if(is_child_of(5, 10))
{
// execute php code if the page with the id of 10 is a child page of 5
}

Why would you use it?

Well, this is up to you entirely, but what I used it for was to style a specific page and all it's numerous levels of subpages with a slightly different stylesheet. So I put this code in the header.php file of my template:

// the id of the top page is 5

if(is_page(5) || is_child_of(5))
{
// php code goes here to include the styleshet
}

So this statement will run if you are viewing a page with the id 5 or any of it's subpages on any number of levels.

Download: 'Is Child Of ' v.0.5

Any questions or feedback, please do let me know So far I've only tested this for 2.7, but I'm pretty certain it should work for 2.5 as well. Any help on this would be greatly appreciated!