Query metas (and not : query posts by metas)

Question

If I understood well, the WP_Meta_Query from Wordpress allows you to query posts by metas.

But what I would like to do is to fetch metas; not posts. And I would like to fetch those metas without any relation to a post ID.

Let's say that I have those entries in my wp_postmeta table :

meta_id | post_id | meta_key | meta_value
  1269      21       vote_up      1
  1268      37       vote_up      17
  1267      12      vote_down     1
  1266      41       vote_up      3
  1265      98      vote_down     3

The meta_value column here is filled with user ids.

What I would like to do is to have a function that counts the rows

• by meta_value (user id)
• by meta_key (vote_up)

And eventually filters the results with certain criteras : ignore lines where posts are not published, for example.

Eg.

function bbpvotes_get_votes_up_by_user_count( $user_id = 0 ){

    if (!$user_id) $user_id = get_current_user_id();

    //meta args
    $metas_args = array(
      'key'     => 'vote_up',
      'value'   => $user_id
    );

    //regular posts args (I would to limit the results to those; so for example unpublished posts will not be returned)
    $post_args = array(
        'post_type' => 'post',
        'post_status'   => 'publish',
    );

    //... 

    return count($returned_metas);
}

Is there a WP core function to do this ? Thanks !

Answer 1

Look at the section on $wpdb->get_results(), it allows you to send distinct queries to the database, which is what it sounds like you are looking to do.

So...

// 1st Method - Declaring $wpdb as global and using it to execute an SQL query statement that returns a PHP object

global $wpdb;
$results = $wpdb->get_results( 'SELECT meta_key, count(meta_key) as votes FROM wp_postmeta WHERE meta_value= ' . $user_id . ' GROUP BY meta_key' );

This should return an array called $results for the user with the following data:

meta_key | votes
-----------------
vote_up  |  15
vote_down|  3

If you want to use a standard function, your other option would be to get all the relevant post_ids, and use get_post_meta( $post_id, $key ) then organize the data in PHP, but the above is more efficient.