Odtnhj

In Wordpress:

I have a need to exclude a certain category of posts from the main WP loop. But only if that post has no other categories.

For example, if the category in question was called X...

Test 1: A post which belongs to only X category would be excluded.

Test 2: A post which belongs to X and Y categories would be included.

Test 3: Posts which belong to Z or Foo or anything else would also be included.

I have the following code so far:

function exclude_category( $query ) 
 if ( $query->is_home() && $query->is_main_query() ) 
 $query->set( 'cat', '-271' );
 


add_action( 'pre_get_posts', 'exclude_category' );

But this works for test 1 and 3 (above) but not test 2. How can I modify the query to achieve this?

I thought up a way to do this, though I am not sure it is the best way.

Basically I am asking WP for a list of all categories then I am concatenating a list of those categories minus the one which I want to exclude. I then feed that into the 'cat' parameter in the WP Query. It seems to work as I would hope, but it also seems a little round-about. I would appreciate any feedback.

In this case 271 is the id for my x category.

function exclude_category( $query ) 

 $terms = get_terms( array(
 'taxonomy' => 'category',
 'hide_empty' => false,
 ) );

 $catquery = "";
 foreach($terms as $term) 
 if($term->term_id != 271) 
 $catquery .= $term->term_id . ",";
 
 

 $catquery = substr($catquery, 0, -1);

 if ( $query->is_home() && $query->is_main_query() ) 
 $query->set( 'cat', $catquery );
 


add_action( 'pre_get_posts', 'exclude_category' );

EDIT

I ended up changing it to a taxonomy query so I could set include_children to false.

function exclude_category( $query ) 

 $terms = get_terms( array(
 'taxonomy' => 'category',
 'hide_empty' => false,
 ) );

 $catarray = ;
 foreach($terms as $term) 
 if($term->term_id != 271) 
 array_push($catarray, $term->term_id);
 
 

 if ( $query->is_main_query() && $query->is_home()) 
 $query->set( 'tax_query', array( array(
 'taxonomy' => 'category',
 'field' => 'term_id',
 'terms' => $catarray,
 'include_children' => false
 )));
 


add_action( 'pre_get_posts', 'exclude_category' );

I would assume that including all category y, will include all posts contained in x and also in y.