WordPress Functions in PHP code

https://codex.wordpress.org/Integrating_WordPress_with_Your_Website

If you're like me, sometimes you want to be able to reference WordPress functions in a page which does not exist in the CMS. This way, it remains backend specific and cannot be accidentally deleted by the client.

This is actually simple to do just by including the wp-blog-header.php file using a php require().

Here's an example that uses a query string to generate Facebook OG data for any post.

Take the example of a link like http://example.com/yourfilename.php?1 where 1 is the ID of a post we want to generate OG data for:

Now in the contents of yourfilename.php which, for our convenience, is located in the root WP directory:

<?php
    require( dirname( __FILE__ ) . '/wp-blog-header.php' );

    $uri = $_SERVER['REQUEST_URI'];
    $pieces = explode("?", $uri);
    $post_id = intval( $pieces[1] );

    // og:title
    $title = get_the_title($post_id);

    // og:description
    $post = get_post($post_id);
    $descr = $post->post_excerpt;

    // og:image
    $img_data_array = get_attached_media('image', $post_id);
    $img_src = null;
    $img_count = 0;

    foreach ( $img_data_array as $img_data ) {
        if ( $img_count > 0 ) {
            break;
        } else {
            ++$img_count;
            $img_src = $img_data->guid;
        }
    } // end og:image

?>
<!DOCTYPE HTML>
<html>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, user-scalable=yes" />
<meta property="og:title" content="<?php echo $title; ?>" />
<meta property="og:description" content="<?php echo $descr; ?>" />
<meta property="og:locale" content="en_US" />  
<meta property="og:type" content="website" />
<meta property="og:url" content="<?php echo site_url().'/your_redirect_path'.$post_id; ?>" />
<meta property="og:image" content="<?php echo $img_src; ?>" />
<meta property="og:site_name" content="Your Title" />
</html>

There you have it: generated sharing models for any post using the post's actual image, excerpt and title!

We could have created a special template and edited the permalink structure to do this, but since it's only needed for one page and because we don't want the client to delete it from within the CMS, this seemed like the cleaner option.

EDIT 2017: Please note that this approach is now deprecated

For WP installations from 2016+ please see https://stackoverflow.com/a/39800534/1958998 for extra parameters to include before outputting your page data to the browser.

If you wanted to create your own .php file and interact with Wordpress without 404 Headers and keeping your current permalink structure there is NO Need for a Template file for that 1 page, I found that this approach works best, in your .php file:

<?php
    require_once(dirname(__FILE__) . '/wp-config.php');
    $wp->init();
    $wp->parse_request();
    $wp->query_posts();
    $wp->register_globals();
    $wp->send_headers();

    // Your Wordpress Functions here...
    echo site_url();
?>

Than you can simply perform any wordpress functions after this. Also, this assumes that your .php file is within the root of your wordpress site where your wp-config.php file is located.

This, to me, is a PRICELESS discovery as I was using require_once(dirname(__FILE__) . '/wp-blog-header.php'); for the longest time as Wordpress even tells you that this is the approach that you should use to integrate Wordpress Functions, cept, it causes 404 headers, which is weird that they would want you to use this approach. https://codex.wordpress.org/Integrating_WordPress_with_Your_Website

I know many people have answered this question and it already has an accepted answer, but here is a nice approach for a .php file within the root of your wordpress site (or technically anywhere you want in your site), that you can browse to and load without 404 Headers!

WordPress Functions in PHP code

OLD WAY

NEW WAY

VQDEV WIKI