wordpress - Sort posts by custom field number -

i'm using query posts.

            $args = array(                  'post_type' => 'spaces',                 'post_per_page' => '500',                 'orderby'     => 'rand',                 'meta_key' => 'space-city',                 'meta_value' => $search,                                   );              $query = new wp_query($args); 

now need order results total of comments on each post. i've custom field number called "space-comments", i've no idea how sort posts second meta_key.

i made tests, able post when "space-comments" has value. when there no value, post don't show up.

any ideia how can start?

the wp_query can accept meta_query argument populated array of sub-arguments. array can have sub arrays each own meta query, can create nice compound searches across meta data.

see example https://codex.wordpress.org/class_reference/wp_query#custom_field_parameters below.

$args = array(     'post_type'  => 'product',     'meta_query' => array(         array(             'key'     => 'color',             'value'   => 'blue',             'compare' => 'not like',         ),         array(             'key' => 'price',             'value'   => array( 20, 100 ),             'type'    => 'numeric',             'compare' => 'between',         ),     ), ); $query = new wp_query( $args );