How to query posts in multiple select relationship field (serialized array)

• serkyen

• July 12, 2015 at 4:52 pm

I have set up 2 custom post types (site & instructor).

For the instructor post type, I have created a relationship custom field (identifier: site) that allows for multiple select and lists the ‘site’ post type.

So for example, I create three sites (site1, site2 and site3).
Then I create an instructor and I select site1 and site3 from the multiple select relationship custom field. So now one instructor is linked to two sites. Now when I view the particular instructor on the front end, I would like to see site1 and site 3 listed.

So far, I am able to use the query below if I disable the multiple select option for the custom field and it all works. However, I would like to be able to add many sites to one instructor and if I enable multiple select, i believe the data in the DB becomes a serialized array which breaks the code below.

$site_id = get_field('site');
$site_query = new WP_Query("post_type=site&p=$site_id");
if ( $site_query->have_posts() ) { while ( $site_query->have_posts() ) {$site_query->the_post();
get_template_part( 'loop-sites' );
}}
wp_reset_postdata();

Any ideas on how I can achieve this?

I have tried changing the query to something like this but it doesn’t work for listing sites on a single instructor. This only works for listing instructors on a single site.

$site_query = new WP_Query(
array(
'post_type' => 'site',
'meta_query' => array(
array(
'key' => 'site',
'compare' => 'LIKE',
'value' => '"' . get_the_ID() . '"'
)
)));

Thanks for any help in advance, it is really appreciated.

• serkyen

• July 13, 2015 at 1:01 am

I guess the question here is…
How would one query a post type, by a custom field that links to it from a different post type?

• John Huebner

• July 13, 2015 at 8:42 am

Try this, use a posts__in

$sites = get_field('site')
if ($sites) {
    $args = array(
        'post_type' => 'site',
        'post_per_page' => -1,
        'posts__in' => $sites,
        'order_by' => 'post__in'
    ); 
    $site_query = new WP_Query($args);
    if ($site_query->have_posts()) {
        while ($site_query->have_posts()) {
            $site_query->the_post();
            get_template_part('loop-sites');
        }
    }
    wp_reset_postdata();
}

• serkyen

• July 13, 2015 at 12:18 pm

Hi John, Thank you for your help…
Unfortunately, it didn’t work.
It just returns all sites.

I tried changing the posts__in line to the following (just to see if it mad a difference) but still just returns all sites instead of the 3 it’s supposed to.

'posts__in' => array(46,89,35),

Just for clarification, if I do the following…

$sites = get_field('site');
print_r($sites);

It returns…
Array ( [0] => 46 [1] => 89 [2] => 35 )

posts__in doesn’t seem to be working as it should.

Thanks again for your help on this.

• John Huebner

• July 13, 2015 at 12:27 pm

Sorry, my mistake, it should be post__in, typo, I made it plural

$sites = get_field('site')
if ($sites) {
    $args = array(
        'post_type' => 'site',
        'post_per_page' => -1,
        'post__in' => $sites,
        'order_by' => 'post__in'
    ); 
    $site_query = new WP_Query($args);
    if ($site_query->have_posts()) {
        while ($site_query->have_posts()) {
            $site_query->the_post();
            get_template_part('loop-sites');
        }
    }
    wp_reset_postdata();
}

• serkyen

• July 13, 2015 at 12:37 pm

Yes! I was just about to post the same thing, all works now 🙂
Thanks so much for your help John.