[wp-trac] [WordPress Trac] #18106: get_terms of posts in a specific post_type

[WordPress Trac]

#18106: get_terms of posts in a specific post_type
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 Reporter:  braydonf         |       Owner:
     Type:  feature request  |      Status:  new
 Priority:  normal           |   Milestone:  Awaiting Review
Component:  Taxonomy         |     Version:
 Severity:  normal           |  Resolution:
 Keywords:                   |
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Changes (by stephenh1988):

 * cc: contact@… (added)


Comment:

 Someone asked how to do this on WordPress Stack Exchange
 http://wordpress.stackexchange.com/a/57449/9364. After implementing the
 above solution (with validation, cache etc). I realised a better way
 *might* be to use a wrapper around `get_terms` and make use of the filter.

 This wrapper function takes the same arguments as `get_terms`, plus a
 `'post_types'` key in the `$args` array. This takes a string|array of post
 types. It works for the defaults - but I haven't verified it for all
 arguments...

 Not exactly future proof (neither solutions are) - but would be great to
 see this feature added at some point. I should image that `count` will
 cause problems as this is stored in the db. The workaround below replaces
 it with an SQL `COUNT(*)`.

 {{{
 function wpse57444_get_terms($taxonomies, $args=array() ){

     if( !empty($args['post_types']) ){
         $args['post_types'] = (array) $args['post_types'];
         add_filter( 'terms_clauses','wpse_filter_terms_by_cpt',10,3);

         function wpse_filter_terms_by_cpt( $pieces, $tax, $args){
             global $wpdb;

             //Don't use db count
             $pieces['fields'] .=", COUNT(*) " ;

             //Join extra tables to restrict by post type.
             $pieces['join'] .=" INNER JOIN $wpdb->term_relationships AS r
 ON r.term_taxonomy_id = tt.term_taxonomy_id
                                 INNER JOIN $wpdb->posts AS p ON p.ID =
 r.object_id ";

             //Restrict by post type and Group by term_id for COUNTing.
             $post_types_str = implode(',',$args['post_types']);
             $pieces['where'].= $wpdb->prepare(" AND p.post_type IN(%s)
 GROUP BY t.term_id", $post_types_str);

             return $pieces;
         }
     }
         $terms = get_terms($taxonomies, $args);
         remove_filter( 'terms_clauses','wpse_filter_terms_by_cpt',10);
         return $terms;
 }
 }}}

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Ticket URL: <http://core.trac.wordpress.org/ticket/18106#comment:4>
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