I'm using category intersection pages for users to be able to filter posts by categories.

E.g. http://freemapsalgarve.com/category/destinations/alvor+bars-pubs/

Here the user is filtering on the "alvor" AND "bars-pubs" child categories of "destinations".

I want to be able to get the id's of the categories that are being filtered on the page so I can display them to the user but I am only able to get the first category.

$this_cat = get_category(get_query_var('cat'));

...returns the first category "alvor" in this example.

Does anyone know how I could find the both categories being filtered on here?

  • What are "category intersection pages"? This is no default WordPress vocabulary. Please elaborate. – kaiser Mar 10 '13 at 20:00
  • In WordPress you can display the intersection or union of two taxonomies using the + or , operators in the url: E.g. /categories/a+b - would show all posts in category A AND B. Some more info here - ryan.boren.me/2007/10/01/taxonomy-intersections-and-unions – David Mar 10 '13 at 20:47
  • Oh, you're simply talking about a tax_query. Why didn't you say that. Ryan Boran uses a wired vocabulary for a core dev. Oh and this post is from WP version 2.3. Things are quite different these days. set_query_var() for example was replaced using $query->set(), etc. Just var_dump( $GLOBALS['wp_query'] ); and post a link to a pastebin (or similar) here. – kaiser Mar 10 '13 at 21:00
  • Here's the output of var_dump: pastebin.com/DxyMPYxq - I can see that there are two category_name fields - one containing both category names and one containing only a single category name. – David Mar 12 '13 at 9:46
  • David, could you please wrap this inside <pre> tags. This is not readable. – kaiser Mar 12 '13 at 11:05

If you're in the loop, simply use get_categories().

  • This just lists out all the categories in the system - I want to know the names of the Categories being displayed on the Category intersection page being viewed - outside the loop. – David Mar 13 '13 at 10:17

If you're not in the loop and want to get the queried terms, then there's no native API function as well as no WP_Query or WP_Tax_Query object method available (like for example get_queried_object()). You'll have to access it directly.

Example of what the tax_query looks like (provided by the OP):

  object(WP_Tax_Query)#282 (2) {
    array(2) {
      array(5) {
        string(8) "category"
        array(1) {
          string(5) "alvor"
        string(4) "slug"
        string(2) "IN"
      array(5) {
        string(8) "category"

Now we need to access that $wp_query object. We'll do that with a small plugin that will output the necessary parts.

defined( 'ABSPATH' ) or exit;
/* Plugin Name: (#90230) Get Taxonomy terms */
add_filter( 'parse_query', 'wpse90230_parse_query' );
function wpse90230_parse_query( $wp_query )
    // This is the tax_query/WP_Tax_Query object
    $tax_query = $wp_query->tax_query; 

    // Now we get the relation `AND`/`OR` so we have a possibilty to the tell the user
    // whether we are showing them a "match" or a "filtered" result
    $relation = 'AND' === $tax_query->relation ? "filtered" : "matched";

    // Then we're extracting the terms.
    // This gives us the terms as array sorted by taxonomy.
    foreach ( $tax_query->queries as $tax_query )
        $terms[ $tax_query["taxonomy"] ] = $tax_query["terms"];

    // Now we can loop through them:
    printf( 'You are viewing %s', get_post_type() );
    foreach ( $terms as $taxonomy => $terms )
             '%s: %s'
            ,get_taxonomy( $taxonomy )->label
            ,join( ",", $terms )
  • Thanks Kaiser - trying out your example at the top of my category page (below the header but before the loop) gives the following output: "You are viewing postCategories: bars-pubs" - it doesn't seem to be seeing the other category "Alvor" which should be there since the path is /category/destinations/alvor+bars-pubs/ – David Mar 13 '13 at 13:59
  • @David Please do a var_dump( $terms ) before the foreach() loop. – kaiser Mar 13 '13 at 14:04
  • Here's the output: array(1) { ["category"]=> array(1) { [0]=> string(9) "bars-pubs" } } from this page - freemapsalgarve.com/category/destinations/alvor+bars-pubs – David Mar 13 '13 at 16:30
  • In this case you seem to do several queries. And this query only holds the bars-pubs term... Seems like you're interfering earlier. I'll write an update. You can then use it and inspect the output. – kaiser Mar 13 '13 at 18:22

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