Appending Post Meta to Beginning of Post Content - php

Question

I'm trying to alter the behavior of the Publish to Apple New Wordpress plugin. My theme uses a custom field for video embeds but the plugin doesn't recognize that content. I'm trying to append the meta to the beginning of the posts in Apple News. This is my code that isn't working:
function add_post_meta_content($content) {
$meta = get_post_meta( get_the_ID(), 'csco_post_embed', true );
return .$meta.$content;
}
add_filter('apple_news_exporter_content_pre', add_post_meta_content);
apply_filters( 'apple_news_exporter_content_pre', $post->post_content, $post->ID );
If I for instance alter the code to the following:
function add_post_meta_content($content) {
$meta = get_post_meta( get_the_ID(), 'csco_post_embed', true );
return 'Print this content before the post'.$meta.$content;
}
add_filter('apple_news_exporter_content_pre', add_post_meta_content);
apply_filters( 'apple_news_exporter_content_pre', $post->post_content, $post->ID );
It appends "Print this content before the post" to the beginning of the post without issue. What am I missing here?

Answer 1

Plugin is already sending $post->ID to your filter, so no need to call get_the_ID().
Try this code:
function add_post_meta_content($content, $post_id) {
$meta = get_post_meta( $post_id, 'csco_post_embed', true );
return 'Print this content before the post'.$meta.$content;
}
add_filter('apple_news_exporter_content_pre', add_post_meta_content, 10, 2);
--
If that doesn't work, make sure that you actually have something saved in the database meta table under csco_post_embed key. Easy way to confirm this is to open your database and do a quick query:
SELECT *
FROM wp_postmeta
WHERE post_id = ENTER_YOUR_POST_ID_HERE AND meta_key = 'csco_post_embed';

Answer 2

Awesome! You got me 99% of the way there. Had to return the oembed to get the video to work. Here's the final code in case someone else comes looking.
function add_post_meta_content($content, $post_id) {
$meta = wp_oembed_get( get_post_meta( $post_id, 'csco_post_embed', true ) );
return $meta.$content;
}
add_filter('apple_news_exporter_content_pre', add_post_meta_content, 10, 2);