I'm using the woocommerce-auto-category-thumbnails plugin to replace a blank category thumbnail with a random thumbnail from one of the products in the category (or child categories).
It is supposed not to use the thumbnail if the products have no thumbnails, using this query
$query_args = array(
'post_status' => 'publish',
'post_type' => 'product',
'posts_per_page' => 1,
'tax_query' => array(
'relation' => 'AND',
array(
'field' => 'id',
'taxonomy' => 'product_cat',
'terms' => $cat->term_id
),
array(
'field' => 'slug',
'taxonomy' => 'product_visibility',
'terms' => 'exclude-from-catalog',
'operator' => 'NOT IN',
),
array(
'key' => '_thumbnail_id',
'value' => '',
'compare' => '!='
)
)
);
to select products in the category.
However, the last term,
array(
'key' => '_thumbnail_id',
'value' => '',
'compare' => '!='
)
have no effect, I've even tried
array(
'key' => '_thumbnail_id',
'value' => '234',
'compare' => '=='
)
and I still get random images, sometimes the placeholder.
The query is being run, because if I change the $cat->term_id to a constant, I get images from the same category all the time.
I guess I could fetch more products and loop until I found one with a real image, but I find that rather wasteful.
Is it possible to fix the query to do what's wanted?