WordPress Custom Post Type with Custom Fields

In functions.php

/*  Being custom post types */

add_action('init', 'pdf_resources_register');
function pdf_resources_register() {

    $labels = [
        'name'               => _x('PDF Resource', 'post type general name'),
        'singular_name'      => _x('PDF Resource', 'post type singular name'),
        'add_new'            => _x('Add New', 'PDF Resource'),
        'add_new_item'       => __('Add New PDF Resource'),
        'edit_item'          => __('Edit PDF Resource'),
        'new_item'           => __('New PDF Resource'),
        'view_item'          => __('View PDF Resource'),
        'search_items'       => __('Search PDF Resources'),
        'not_found'          =>  __('Nothing found'),
        'not_found_in_trash' => __('Nothing found in Trash'),
        'parent_item_colon'  => ''
    ];

    $args = [
        'labels'             => $labels,
        'public'             => true,
        'publicly_queryable' => true,
        'show_ui'            => true,
        'query_var'          => true,
        'rewrite'            => true,
        'capability_type'    => 'post',
        'hierarchical'       => false,
        'menu_position'      => null,
        'supports'           => [ 'title', 'editor', 'thumbnail' ],
        'rewrite'            => [ 'slug' => 'pdf_resource' , 'with_front' => FALSE ]
      ];

    register_post_type( 'pdf_resource' , $args );
}

add_action("admin_init", "admin_init");

function admin_init(){
  add_meta_box("pdf-meta", "Upload", "pdf_meta", "pdf_resource", "side", "low");
}

function pdf_meta() {
  global $post;
  $custom   = get_post_custom($post->ID);
  $pdf_file = $custom["pdf_file"][0];
  echo '<input type="hidden" name="mytheme_meta_box_nonce" value="', wp_create_nonce(basename(__FILE__)), '" />';
  ?>
  <p><label>PDF File:</label><br />
  <input type="text" name="pdf_file" id="pdf_file" value="<?php echo $pdf_file; ?>" style="width:258px">
  <input type="button" name="pdf_button" id="pdf_button" value="Browse" style="width:258px"></p> 
  <?php
}

register_taxonomy( "pdf_category", [ "pdf_resource" ], [ "hierarchical" => true, "label" => "Categories", "singular_label" => "Category", "rewrite" => true ] );
register_taxonomy( "pdf_color", [ "pdf_resource" ], [ "hierarchical" => true, "label" => "Colors", "singular_label" => "Color", "rewrite" => true ] );

function my_admin_scripts() {
    wp_enqueue_script('media-upload');
    wp_enqueue_script('thickbox');
    wp_register_script('my-upload', get_bloginfo('template_url') . '/js/my-script.js', [ 'jquery', 'media-upload', 'thickbox' ] );
    wp_enqueue_script('my-upload');
} 

function my_admin_styles() {
    wp_enqueue_style('thickbox');
}

add_action('admin_print_scripts', 'my_admin_scripts');
add_action('admin_print_styles', 'my_admin_styles');

add_action('save_post', 'save_details');
function save_details(){
    global $post;

    if( $post->post_type == "pdf_resource" ) {
        update_post_meta($post->ID, "pdf_file", $_POST["pdf_file"]);
    }

}
/*  End custom post types */

In js/my-script.js I have the following which allows me to upload a file directly to the custom post type.

jQuery(document).ready(function() {
     jQuery('#pdf_button').click(function() {
         window.send_to_editor = function(html) {
          imgurl = jQuery(html).attr('src') || jQuery(html).find('img').attr('src') || jQuery(html).attr('href');
          jQuery('#pdf_file').val(imgurl);
         tb_remove();
      }
      tb_show('', 'media-upload.php?type=image&TB_iframe=true');
      return false;
     });
});

In index-fact-sheets.php I display the PDF in various colors. To see the live version of this check out Fact Sheets and Handouts

<?php
/*
Template Name: Fact Sheets Template
*/
?><?php get_header(); ?>
<div id="container">

        <div id="mainbar">

            <h1>Fact Sheets</h1>

            <?php 
              $temp                = $wp_query;
              $paged               = (get_query_var('paged')) ? get_query_var('paged') : 1;
              $post_per_page = 100; // -1 shows all posts
              $args = [
                'post_type'      => 'pdf_resource',
                'orderby'        => 'date',
                'order'          => 'ASC',
                'paged'          => $paged,
                'pdf_category'   => 'fact-sheets',
                'posts_per_page' => $post_per_page
              ];
              $wp_query = new WP_Query($args); 

              if( have_posts() ) : while ($wp_query->have_posts()) : $wp_query->the_post();
                  $custom           = get_post_custom($post->ID);
                  $pdf_file         = $custom["pdf_file"][0];
                  $termsObjects     = wp_get_object_terms($post->ID, 'pdf_color');
                  $currentCustomCat = $termsObjects[0]->slug;
             ?>

            <div class="post-block<?php 
                if ($currentCustomCat == "teal") { echo " teal"; }
                if ($currentCustomCat == "orange") { echo " orange"; }
                if ($currentCustomCat == "green") { echo " green"; }
                if ($currentCustomCat == "light-orange") { echo " ltorange"; }
                if ($currentCustomCat == "light-green") { echo " ltgreen"; }
                if ($currentCustomCat == "red") { echo " red"; }
                ?>"> 
                <a href="<?php if ($pdf_file) { echo $pdf_file; } else { echo "#"; } ?>"><?php the_title(); ?><span>Download PDF</span></a>
                <?php edit_post_link('Edit', '<div class="post-edit-link">', '</div>'); ?>
            </div>
            <?php endwhile; else: ?>
            <?php endif; wp_reset_query(); $wp_query = $temp; the_post(); ?>
        </div>

        <div id="sidebar">
            <ul>
                <?php if ( is_active_sidebar( 'sidebar-widget-area' ) ) : ?>
                    <?php dynamic_sidebar( 'sidebar-widget-area' ); ?>
                <?php endif; ?>
            </ul>
        </div>
</div>
<?php get_footer(); ?>