How To Fix WP Query Returns Results But Shouldn't?

Question

I have a WP Query that should return no results, but instead seems to be returning items. I'm guessing the null result is being interpreted as "return all results" but I'm not sure the proper fix. It looks like this:

    $pairedThing = get_field('myThing');
    $args = array(
    'posts_per_page'=> 2,
    'post_type'     => 'thing',
    'meta_key'      => 'identifier',
    'meta_value'    => $pairedThing,
    );
    
    $the_query = new WP_Query( $args ); ?>
    <?php if( $the_query->have_posts() ): ?>
    <?php while( $the_query->have_posts() ) : $the_query->the_post(); ?>
        <tr><td>Name</td><td>
            <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
        </td></tr>
    <?php endwhile; else: 
                            //{echo 'None';}
    ?>
    <?php endif; ?>

Each query will either have a single result (if there is a match to the query) or no results. When there is a match everything works as planned, but when there is no match the most recent result in the post_type are return, when I would expect nothing to be returns.

Any ideas? I trued the "else" but it didn't work.

Answer 1

Couple of things to consider here:

1.) Try adding the meta query only if the value is present:

$pairedThing = get_field('myThing');
$args = [
    'posts_per_page' => 2,
    'post_type'      => 'thing',    
];
if ( ! empty( $pairedThing ) ) {
    $args['meta_key']   = 'identifier';
    $args['meta_value'] = $pairedThing;
}

2.) Account for posts without the meta-key set:

$pairedThing = get_field('myThing');
$args = [
    'posts_per_page' => 2,
    'post_type'      => 'thing',
    'meta_query'     => [
        'my_meta_query' [ // Multiple meta-queries per handle.
            'relation' => 'OR',
            [
                'key'     => 'identifier',
                'value'   => $pairedThing,
                'compare' => '=',
            ],
            [
                'key'     => 'identifier',
                'compare' => 'NOT EXISTS',
            ],
        ],
    ]
];