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Show an image to facebook, but show a full page to users
<?php
/**
* Template Name: Facebook sees the image
*
**/
/**
* Force no caching, just in case you have some fancy varnish, load balancer
* or other things
**/
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
function show_image_to_facebook(){
// set default value
$redirect = true;
// Check for facebook bots
$pattern = '/(FacebookExternalHit|visionutils|Facebot)/i';
$agent = filter_input(INPUT_SERVER, 'HTTP_USER_AGENT', FILTER_SANITIZE_ENCODED);
if(preg_match($pattern,$agent)){
$redirect = false;
}
// exit early if not facebook
if($redirect){
return;
}
// get the post ID outside the loop
global $wp_query;
$id = $wp_query->post->ID;
// get the image url
$url = get_the_post_thumbnail_url($id, 'gif_image');
// get the image path
$path = parse_url($url, PHP_URL_PATH);
// check if the file exists, and exit if it is not found
if(!file_exists($path)){
return;
}
// set the mime type of the file so it displays properly
header("content-type: " . mime_content_type($path));
// output the image
readfile($path);
// stop all processing as facebook is complete
exit;
}
// Try to show image to facebook if it this is a facebook bot and the file exists
show_image_to_facebook();
get_header();
if ( have_posts() ) {
while ( have_posts() ) {
the_post();
//
// Post Content here
//
} // end while
} // end if
get_footer();
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