WordPress RSS feed - filter RSS content by custom field value

Question

I can have the RSS feed url like:

http://www.mydomain.com/?post_type=job_listing&job_cat=value#1&job_type=value#2&geo_country=value#3&feed=rss2

job_cat & job_type are taxonomies for the job_listing post type and they are considered / generated in the RSS feeds correctly.

Recently I've added a custom field parameter in te RSS feed url's called geo_country. If a value is returned for this in the RSS feed url (not empty), then the RSS content should be filtered also by the custom field's value. Which is not happening currently, of course.

Using the Jobbroller theme, but I haven't found in them any RSS related code, function(s).

Is there any way to write a hook in the described scenario?

Answer 1

You can try to add geo_country as an extra query variable with:

/**
 * Add the 'geo_country' as a public query variable
 *
 * @param array $query_vars
 * @return array $query_vars
 */ 
function my_query_vars( $query_vars ) 
{
    $query_vars[] = 'geo_country';
    return $query_vars;
}

add_filter( 'query_vars', 'my_query_vars' );

and then setup a pre_get_posts hook to filter your feed according to the geo_country value:

/**
 * Filter the feed by the 'geo_country' meta key 
 *
 * @param WP_Query object $query
 * @return void 
 */ 
function my_pre_get_posts( $query ) 
{
    // only for feeds
    if( $query->is_feed && $query->is_main_query() ) 
    {
        // check if the geo_country variable is set 
        if( isset( $query->query_vars['geo_country'] ) 
                && ! empty( $query->query_vars['geo_country'] ) )
        {

            // if you only want to allow 'alpha-numerics':
            $geo_country =  preg_replace( "/[^a-zA-Z0-9]/", "", $query->query_vars['geo_country'] ); 

            // set up the meta query for geo_country
            $query->set( 'meta_key', 'geo_country' );
            $query->set( 'meta_value', $geo_country );
        }

    } 
}

add_action( 'pre_get_posts', 'my_pre_get_posts' );

I assume geo_country takes only alpha-numeric values (a-z,A-Z,0-9), just let me know if that's not the case.

This works on my install with the Twenty Twelve theme.