WP Query works outside a function, not inside a function

Question

Solution: what worked in the end was adding

  global $post;

at the top of the query, so before

$custom_taxterms = ...

Bill Erickson's Genesis custom loop is the template I followed in the end.

Original question

I was hoping for some help with an issue that has me stumped.

I have the following query. It works and outputs data.

$custom_taxterms = wp_get_object_terms( $post->ID, 'region', array('fields' => 'ids') );
// arguments
$args = array(
    'post_type' => 'stay',
    'post_status' => 'publish',
    'posts_per_page' => 25, // you may edit this number
    'orderby' => 'rand',
    'tax_query' => array(
        array(
            'taxonomy' => 'region',
            'field' => 'id',
            'terms' => $custom_taxterms
        )
    ),
    'post__not_in' => array ($post->ID),
);
$related_items = new WP_Query( $args );
// loop over query
if ($related_items->have_posts()) :
    echo '<ul>';
    while ( $related_items->have_posts() ) : $related_items->the_post();
        ?>
        <li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
        <?php
    endwhile;
    echo '</ul>';
endif;
// Reset Post Data
wp_reset_postdata();

If I now put it into a function, it stops working.

add_action( 'genesis_loop', 'related_posts_cpt' );
function related_posts_cpt (){
    // same loop as above
}

Just to be clear, if I use the same function with a different output, it does work:

add_action( 'genesis_loop', 'related_posts_cpt' );
function related_posts_cpt() { 
    ?>
    <p>AAAAAAAAHHHHHH</p>
    <?php
}

What am I missing? Thank you in advance.

Answer 1

functions return an output. you don't want to just echo it out.

try this as your function:

function mycoolquery() {
    $custom_taxterms = wp_get_object_terms( $post->ID, 'region', array('fields' => 'ids') );
// arguments
    $args = array(
        'post_type' => 'stay',
        'post_status' => 'publish',
        'posts_per_page' => 25, // you may edit this number
        'orderby' => 'rand',
        'tax_query' => array(
            array(
                'taxonomy' => 'region',
                'field' => 'id',
                'terms' => $custom_taxterms
            )
         ),
        'post__not_in' => array ($post->ID),
    );
    $related_items = new WP_Query( $args );
// loop over query
    if ($related_items->have_posts()) :
       $output =  '<ul>';
       while ( $related_items->have_posts() ) : $related_items->the_post();

            $output .= '<li><a href="'.the_permalink().'">'.the_title().'</a></li>';

        endwhile;
        $output .= '</ul>';
    endif;
    // Reset Post Data
    wp_reset_postdata();
    return $output;
}

then echo out the function where you want it:

echo mycoolquery();