How could one grab the post meta key of _octopus_id and store that as an array.

Here is what I'm trying to achieve:

  • Call the WP_Query and pull all the offices with _octopus_id
  • Use the value of _octopus_id and store it in an array
  • End goal: Just print out a array with just the _octopus_id values

Could someone tell me what I might be doing wrong? The is_array($posts) prints out true, but I just can't figure out how to store the keys value there.

Full code:

    /* Set the WP offices in an array */
    $ids = new WP_Query([
        'post_type' => 'office',
        'post_status' => 'any',
        'posts_per_page' => 10,
        'meta_query'     => array(
                'key'        => '_octopus_id',

    $posts[] = $ids->posts;

  • So you want an array of _octopus_id that are currently used by at least one office?
    – kero
    Nov 11, 2019 at 17:40
  • @kero, Correct - I'd like to loop through those 10 posts and store the _octopus_id key values into an array.
    – DevSem
    Nov 11, 2019 at 17:40

1 Answer 1


I don't think WP_Query returns the meta fields for you as well. So you need to loop over the posts and run get_post_meta() manually. Assuming one office has at max one _octopus_id, you could write it like this:

// here we will store the ids
$octopiIds = [];

$query = new WP_Query([
    'post_type' => 'office',
    'post_status' => 'any',
    'posts_per_page' => 10,
    'meta_query'     => [
            'key'        => '_octopus_id',
while ($query->have_posts()) {
    $octopiIds[] = get_post_meta(get_the_ID(), '_octopus_id', true);

Do you really need the pagination of WP_Query? If not, I would suggest writing your own query via $wpdbs get_col(), as it can save you alot of queries. The code above will create at least 11 queries (1 for WP_Query, 1 for each post to get the meta), but you can do this in only one.


global $wpdb;
$octopiIds = $wpdb->get_cols(
        SELECT DISTINCT pm.meta_value
        FROM {$wpdb->posts} AS p
        INNER JOIN {$wpdb->postmeta} AS pm
            ON p.ID = pm.post_id AND pm.meta_key = '_octopus_id'
        WHERE pm.meta_value != '' AND pm.meta_value IS NOT NULL

As an additional note, if you're storing some kind of relationship between octopi and offices here, consider using a taxonomy instead of postmeta, as it will speed things up alot.

  • 1
    This helped so much! Thanks a bunch!
    – DevSem
    Nov 11, 2019 at 19:49

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