Add a Copyright Field to the Media Uploader in WordPress

When you upload something into WordPress using the Media Uploader, you can include information such as a caption or a description. If you wanted to include something else, you would first have to create a custom field by hooking into the attachment_fields_to_edit filter. I decided to add a “Copyright” field so that I could credit each item I upload to the original copyright owner and displayed on the front end wherever I want.
Here is the code you need to add to your functions.php file:

/**
 * Adding a "Copyright" field to the media uploader $form_fields array
 *
 * @param array $form_fields
 * @param object $post
 *
 * @return array
 */
function add_copyright_field_to_media_uploader( $form_fields, $post ) {
	$form_fields['copyright_field'] = array(
		'label' => __('Copyright'),
		'value' => get_post_meta( $post->ID, '_custom_copyright', true ),
		'helps' => 'Set a copyright credit for the attachment'
	);
	return $form_fields;
}
add_filter( 'attachment_fields_to_edit', 'add_copyright_field_to_media_uploader', null, 2 );
/**
 * Save our new "Copyright" field
 *
 * @param object $post
 * @param object $attachment
 *
 * @return array
 */
function add_copyright_field_to_media_uploader_save( $post, $attachment ) {
	if ( ! empty( $attachment['copyright_field'] ) )
		update_post_meta( $post['ID'], '_custom_copyright', $attachment['copyright_field'] );
	else
		delete_post_meta( $post['ID'], '_custom_copyright' );
	return $post;
}
add_filter( 'attachment_fields_to_save', 'add_copyright_field_to_media_uploader_save', null, 2 );
/**
 * Display our new "Copyright" field
 *
 * @param int $attachment_id
 *
 * @return array
 */
function get_featured_image_copyright( $attachment_id = null ) {
	$attachment_id = ( empty( $attachment_id ) ) ? get_post_thumbnail_id() : (int) $attachment_id;
	if ( $attachment_id )
		return get_post_meta( $attachment_id, '_custom_copyright', true );
}

With the above code in place, you can now use the following snippet to display your attachment’s new “Copyright” field within one of your page templates.

If you leave the attachment ID parameter blank, it will display the featured image “Copyright” if your post has a featured image set.