Return all Tags from search results

Question

I am wondering if it is possible to return a list of all the "tags" that are associated with ALL returned posts. In theory, I would then use this list of terms to build appropriate "filter by" links for refining the search.

For instance: A user searches for "Foo" and there are 100 results. Would it be possible to get a collection of all the posts' tags? So, post "Foo 1" might be tagged "little bar" and post "Foo 2" might be tagged, "big bar" and "foo foo", etc and etc.

I would like to do this before the while_posts() is doing its thing. Failing that, I think I could use the while_posts() loop to collect all the tags for each post. This is the most obvious solution to me, except that then the list isn't where I want it in the markup. AND, I'm not sure how to include tags on page 2 (and onward) of the results.

Answer 1

The global $wp_query object is available before you call have_posts(). All you have to do is running through this object’s posts member with get_the_terms().

Sample function:

function get_query_terms( $taxonomy = 'post_tag' )
{
    $list = array ();

    foreach ( $GLOBALS['wp_query']->posts as $id )
    {
        if ( $terms = get_the_terms( $id, $taxonomy ) )
        {
            foreach ( $terms as $term )
                $list[ $term->term_taxonomy_id ] = $term;
        }
    }

    ksort( $list );

    return $list;
}

Be aware any usage of query_posts() might break this list.