Using custom fields in a filter hook

Question

I'd like to add some code from a single post theme file into a filter but I'm not sure how to do it because it includes the get_post_meta() function. I've searched but can't seem to figure it out.

Code in single-post.php theme file:

$apoth_original_title = get_post_meta( get_the_ID(), 'original_blog_title', true);
$apoth_original_url = get_post_meta( get_the_ID(), 'original_url', true);
?>
<a id="apoth_readmore" class="w-btn style_solid size_medium color_primary icon_none" href="<?php echo $apoth_original_url?>"><span class="w-btn-label">Read More at <em><?php echo $apoth_original_title ?></em></span></a>
<?php

Attempted filter in functions.php:

function apoth_readmore_link( $content ) {
if( is_single() ) {

    $content .= '<a href="' . get_post_meta(get_the_ID(), 'original_url', true) . '"> Read More</a>' ;
}
return $content;
}

add_filter('the_content', 'apoth_readmore_link' )

I get that this isn't working because get_post_meta() doesn't echo the custom field data, but I don't know how to assign that to a variable and then echo it in the context of a filter function. Or maybe there is some other way of doing this that I'm missing?

Answer 1

Try get_queried_object() to reference the WP_Post that created the page.

• if you're on a single post, it will return the post object
• if you're on a page, it will return the page object
• if you're on an archive page, it will return the post type object
• if you're on a category archive, it will return the category object
• if you're on an author archive, it will return the author object
• etc.

function apoth_readmore_link( $content ) {

    $post = get_queried_object();

    if ( get_class($post)==='WP_Post' ) {

        $url = get_post_meta($post->ID, 'original_url', true);

        $content .= sprintf( '<a href="%s">Read More</a>', $url, $url );
    }

    return $content;
}

add_filter('the_content', 'apoth_readmore_link' );