Get the WordPress post ID no matter where you are.

WordPress get_the_ID() replacement.md

This extends the built-in WordPress function get_the_ID() to return the post ID both inside and outside the loop.

Used outside the loop (in header.php):

<?php if ( function_exists( 'gt_hide_nav' ) && ! gt_hide_nav() ) : ?>
  <nav role="navigation">
    <?php if ( function_exists( 'bones_main_nav' ) ) bones_main_nav(); ?>
  </nav>
<?php endif; // hide nav ?>

Used inside the loop on a page (part of a shortcode):

<?php
function gt_wistia_enqueue() {
  if ( has_shortcode( 'wistia' ) ) {
		wp_enqueue_script( 'wistia-embed-shepherd', '//fast.wistia.com/static/embed_shepherd-v1.js', array(), 'v1', false );
	}
}
add_filter( 'the_post', 'gt_wistia_enqueue' );

functions.php

<?php
/**
 * Gets the ID of the post, even if it's not inside the loop.
 *
 * @uses WP_Query
 * @uses get_queried_object()
 * @extends get_the_ID()
 * @see get_the_ID()
 *
 * @return int
 */
function gt_get_the_ID() {
  if ( in_the_loop() ) {
    $post_id = get_the_ID();
  } else {
    /** @var $wp_query wp_query */
    global $wp_query;
    $post_id = $wp_query->get_queried_object_id();
    }
  return $post_id;
}

/**
 * Hide nav if option checked in page editor.
 *
 * @return bool
 */
function gt_hide_nav() {
    $post_id  = gt_get_the_ID();
    $meta_key = '_gt_hide_nav';
    $hide_nav = false;

    if ( ! empty( $post_id ) ) {
        $hide_nav = 'on' == get_post_meta( $post_id, $meta_key, true ) ? true : false;
    }

    return $hide_nav;
}

/**
 * Check the current post for the existence of a short code
 *
 * @link http://wp.tutsplus.com/articles/quick-tip-improving-shortcodes-with-the-has_shortcode-function/
 *
 * @param string $shortcode
 *
 * @return bool
 */
function has_shortcode( $shortcode = '' ) {
    //global $post;
    //$post_to_check = get_post();
    $post_to_check = get_post( gt_get_the_ID() );

    // false because we have to search through the post content first
    $found = false;

    // if no short code was provided, return false
    if ( ! $shortcode ) {
        return $found;
    }
    // check the post content for the short code
    if ( false !== stripos( $post_to_check->post_content, '[' . $shortcode ) ) {
        // we have found the short code
        $found = true;
    }

    // return our final results
    return $found;
}

gt_get_the_ID.php

<?php
// Add to theme's functions.php file.

/**
 * Gets the ID of the post, even if it's not inside the loop.
 *
 * @uses WP_Query
 * @uses get_queried_object()
 * @extends get_the_ID()
 * @see get_the_ID()
 *
 * @return int
 */
function gt_get_the_ID() {
  if ( in_the_loop() ) {
    $post_id = get_the_ID();
  } else {
    /** @var $wp_query wp_query */
    global $wp_query;
    $post_id = $wp_query->get_queried_object_id();
    }
  return $post_id;
}