Insert custom field value before content - php

Question

I have a custom meta field that I would like to insert in the_content automatically so that my AMP plugin can render the custom field value in the same way as the_content.
Currently I am using this code to display it:
<?php $video_value = get_post_meta( get_the_ID(), '_video', true ); ?>
<?php if ( ! empty( $video_value ) ) {?>
<div class="video-container"><?php echo $video_value; ?></div>
<?php } else { ?>
<?php the_post_thumbnail(); ?>
<?php } ?>
But I would like the $video_value to be inserted automatically before the_content.

Answer 1

You can use the the_content filter to do this. You can read more about it on the WordPress developer site.
But the code could be looking something like this:
function my_custom_content_filter($content){
global $post;
$video_value = get_post_meta($post->ID, '_video', true);
if($video_value){
return '<div class="video-container">' . $video_value . '</div>' . $content;
}else{
return get_the_post_thumbnail($post->ID) . $content;
}
}
add_filter('the_content', 'my_custom_content_filter');
And you can add this code in you functions.php file.
Note This filter only works on the_content() and not get_the_content()

Answer 2

You can do something like this -
and add the conditions that you want -
You might need to access Global $post to get the meta value
function custom_weird_name_before_after($content) {
if(is_page() || is_single() || $yourOwnConditions == true) {
$beforecontent = 'This line will go before the content - populate with whatever.';
$aftercontent = 'This will come after the content - makes sense right?';
$fullcontent = $beforecontent . $content . $aftercontent;
} else {
$fullcontent = $content;
}
return $fullcontent;
}
add_filter('the_content', 'custom_weird_name_before_after');
You can add this in functions.php