Using Custom Meta Box Date in WordPress Loop - php

Question

I'm using the below script in the functions.php file to upload a PDF to a custom post type, however I am unsure of how to then retrieve the PDF URL within the WordPress Loop:
function add_custom_meta_boxes() {
add_meta_box('wp_custom_attachment', 'PDF Newsletter', 'wp_custom_attachment', 'newsletter', 'normal', 'high');
}
add_action('add_meta_boxes', 'add_custom_meta_boxes');
function wp_custom_attachment() {
wp_nonce_field(plugin_basename(__FILE__), 'wp_custom_attachment_nonce');
$html = '<p class="description">';
$html .= 'Upload your PDF here.';
$html .= '</p>';
$html .= '<input type="file" id="wp_custom_attachment" name="wp_custom_attachment" value="" size="25">';
$filearray = get_post_meta( get_the_ID(), 'wp_custom_attachment', true );
$this_file = $filearray['url'];
if($this_file != ""){
$html .= '<div>Current file:<br>"' . $this_file . '"</div>';
}
echo $html;
}
add_action('save_post', 'save_custom_meta_data');
function save_custom_meta_data($id) {
if(!empty($_FILES['wp_custom_attachment']['name'])) {
$supported_types = array('application/pdf');
$arr_file_type = wp_check_filetype(basename($_FILES['wp_custom_attachment']['name']));
$uploaded_type = $arr_file_type['type'];
if(in_array($uploaded_type, $supported_types)) {
$upload = wp_upload_bits($_FILES['wp_custom_attachment']['name'], null, file_get_contents($_FILES['wp_custom_attachment']['tmp_name']));
if(isset($upload['error']) && $upload['error'] != 0) {
wp_die('There was an error uploading your file. The error is: ' . $upload['error']);
} else {
add_post_meta($id, 'wp_custom_attachment', $upload);
update_post_meta($id, 'wp_custom_attachment', $upload);
}
}
else {
wp_die("The file type that you've uploaded is not a PDF.");
}
}
}
function update_edit_form() {
echo ' enctype="multipart/form-data"';
}
add_action('post_edit_form_tag', 'update_edit_form');
Here is the loop I am using, including my failed attempt of adding the PDF url:
<?php
$args = array( 'post_type' => 'newsletter', 'posts_per_page' => 10 );
$loop = new WP_Query( $args );
while ( $loop->have_posts() ) : $loop->the_post();
the_title();
echo '<div class="entry-content">';
the_content(); ?>
<?php
$news_pdf = get_post_meta( $post_id, 'wp_custom_attachment', true );
$news_pdf['url']
?>
<?php echo '</div>';
endwhile;
?>

Answer 1

Please first change $post_id to get_the_ID() within your loop.
Change $news_pdf['url'] to:
echo $news_pdf['url'];
Thanks