If else statement based on referral URL

Question

I am trying to display content in a custom template based on referral URL. I put a link in my footer called http://domain.com/?ref=special and image2.gif shows still when I click it and go to the page. I need image1.gif to show if there is traffic coming from a domain that ends with ?ref=special. How can I do this and what am I missing?

   <?php
      $ref1 = parse_url(wp_get_referer()); //getting the referring URL
      if($ref1["path"]=='/?ref=special/')
  :?>
    <div id="featured_image_small" style="background: url('<?php echo esc_url( home_url( '/wp-content/uploads/2015/05/image1.gif' ) ); ?>') no-repeat scroll 0 0 transparent; background-size:cover;">
  <?php else: ?>
    <div id="featured_image_small" style="background: url('<?php echo esc_url( home_url( '/wp-content/uploads/2015/04/image2.jpg' ) ); ?>') no-repeat scroll 0 0 transparent; background-size:cover;">
  <?php endif ;?>

Answer 1

a $_GET variable would be the better option.

try var_dump($_GET); on the page before the conditional and see exactly what you need to test against

It seems that there is something more to the puzzle that we are missing. Is the file not showing up correctly? Could that be because the file paths are wrong? Or is it always showing the wrong image?

Also, I would say to save the image-filename as a variable based on that conditional to keep your code a little cleaner.

if ($_GET['ref'] == 'special') { 
  $file = '/wp-content/uploads/2015/05/image1.gif';
} else {
  $file = '/wp-content/uploads/2015/04/image2.gif';
}
?>

<div id="featured_image_small" style="background: url('<?php echo esc_url( home_url( $file ) ); ?>') no-repeat scroll 0 0 transparent; background-size:cover;">

Answer 2

The following worked for me.

functions.php

function add_query_vars_filter( $vars ){
  $vars[] = "ref";
  return $vars;
}

custom template

  <?php
       if($_GET['ref'] == 'special')
   :?>
     //do something
   <?php else: ?>
    //do something
  <?php endif ;?>