Last Updated: February 28, 2019 | Reading Time: < 1 minute
On a loop that performs data from custom meta field, to check if the meta key has value or exist, we can use the following query:
$testimonials = array(
'post_type' => 'projects',
'posts_per_page' => 4,
'meta_key' => 'testimonial',
'meta_value' => array(''),
'meta_compare' => 'NOT IN'
);
The above code can be used in WordPress older than 3.5 but it still usable in the latest version of WP, currently 5.1.