I would like to filter all post queries by a specific term of a custom taxonomy (specified by an url). Currently I'm using add_filter('request', ...) and 'tax_query', which kind of works now.
So I get all posts of this term, but I would like to get those posts, which do not have ANY terms allocated of this taxonomy.
I was trying something like:
$request['tax_query'] = array(
'relation' => 'OR',
array(
'taxonomy' => 'brand',
'field' => 'slug',
'terms' => array( $term )
),
array(
'taxonomy' => 'brand',
'field' => 'slug',
'terms' => NULL,
'operator' => 'IS'
),
);
But, since Wordpress doesn't support 'IS' or 'IS NULL' this doesn't work either.
So, any idea how to query for posts of a term AND posts without a term at all?
EDIT: Another solution would be to query all terms, an exclude it then in tax_query. But I would like to save this query.