Auto generate featured WP image

auto-generate-wp-featured-image.php

<?php

/**
 * generate featured image automatically
 * @author @david <[email protected]>
*/
function autogen_featured_img() {
	global $post;
	if (!has_post_thumbnail($post->ID)) {
		$attached_image =
			get_children( "post_parent=$post->ID&post_type=attachment&post_mime_type=image&numberposts=1" );
		if ($attached_image) {
				foreach ($attached_image as $attachment_id => $attachment) {
				set_post_thumbnail($post->ID, $attachment_id);
			}
		}
	}
}
/*This line is used to generate featured images for all old
posts. Remove this once the default images get generated
for all of the old posts*/
add_action('the_post', 'autogen_featured_img');
/* For new upcoming posts, leave them permanently*/
add_action('save_post', 'autogen_featured_img');
add_action('draft_to_publish', 'autogen_featured_img');
add_action('new_to_publish', 'autogen_featured_img');
add_action('pending_to_publish', 'autogen_featured_img');
add_action('future_to_publish', 'autogen_featured_img');

?>