Filtering by relationship field in pre_get_posts on post archive page

• kstarcher

• October 5, 2017 at 11:04 am

Hello –

I have a custom post type, “industries”, that news posts can select from in a Relationship field called “related_industries”. I have no problem getting a list of related industries on the post page, or anywhere that related_industries exists, or getting the list of posts on the single-industry page with the reverse lookup. But I’d like to be able to filter the results on the post archive page by industry, using a query var. It seems in theory that I should be able to do it the same way as I would on a single-industry page, but it doesn’t seem to affect the query at all. I’ve tried a lot of different variations, too many to list, but I’m starting to wonder if it’s possible (especially since I haven’t seen too many people asking the same question).

This is basically the code – a few things have been simplified posting it here (because I’m trying to do this with multiple CPTs) but this should give you the gist of it. Any idea what I might be missing? Thanks!

function query_by_relationship( $query ) {
	
	if( is_admin() ) {
		return $query;
	}
	if (is_archive()) {	
		if( isset($_GET['related_industries']) ) {
			$meta_query[] = array(
							array(
								'key' 		=> 'related_industries',
								'value' => '"' . $_GET['related_industries'] . '"',
								'compare' 	=> 'LIKE',
							)
						);
			$query->set('meta_query', $meta_query);
    		} 
		
	}
	
	
	// return
	return $query;

}

add_action('pre_get_posts', 'query_by_relationship');

• John Huebner

• October 5, 2017 at 11:19 pm

There is an issue here

$meta_query[] = ...

should be

$meta_query =

If that does not help, what is in $_GET['related_industries'], does this only have a single selection or can multiple selections be made?

• kstarcher

• October 6, 2017 at 3:36 am

Well, this is awkward. I had taken that code out of functions.php to try things another way. I pasted back in my code from above, tweaked a few var names as needed, and it worked perfectly fine (whether or not I had the [] in, tried it both ways). So whatever the problem in the code was, it must have been one of the extra bits that I had in there before stripping it down to post on the forum!

Thanks anyway for your response, apparently I just needed a sounding board 😉

• John Huebner

• October 6, 2017 at 3:39 am

meta query allows nested queries, do something like

$meta_query = array(
  array(
    array(
      // actual query here
    )
  )
)

will work, however, this can cause the query to run slower and you’re better off without the extra nesting if you don’t need it.

• kstarcher

• October 6, 2017 at 4:16 am

Hmmm, spoke too soon. My code now works fine on post archive pages, but I need to add it to the CPT “events” as well, which uses the exact same set of custom fields. But this isn’t working. I can test and see that it is correctly triggering the various if statements, but it doesn’t seem that the meta query gets applied – it just returns all results, unfiltered. Posts are still working, though, with the exact code below. Does this sort of meta query get applied differently to a CPT than to the standard post?

function query_by_relationship( $query ) {
    
    if( is_admin() ) {
        return $query;
    }

    if ((is_archive() && $query->is_main_query()) || ( isset($query->query_vars['post_type']) && $query->query_vars['post_type'] == 'events' ) ) { 
        
        if( isset($_GET['sector']) ) {
            $meta_query = array(
                            array(
                                'key'       => 'related_industries',
                                'value' => '"' . $_GET['sector'] . '"',
                                'compare'   => 'LIKE',
                            )
                        );
            $query->set('meta_query', $meta_query);
        } else if( isset($_GET['pa']) ) {
            $meta_query = array(
                            array(
                                'key'       => 'related_practice_areas',
                                'value' => '"' . $_GET['pa'] . '"',
                                'compare'   => 'LIKE',
                            )
                        );
            $query->set('meta_query', $meta_query);
        } else if( isset($_GET['lawyer']) ) {
            $meta_query = array(
                            array(
                                'key'       => 'related_people',
                                'value' => '"' . $_GET['lawyer'] . '"',
                                'compare'   => 'LIKE',
                            )
                        );
            $query->set('meta_query', $meta_query);
        }
        
    }
    
    
    // return
    return $query;

}

add_action('pre_get_posts', 'query_by_relationship');