Default Post Tag for Custom Post Type

function wpm_add_custom_types( $query ) {
	if( is_category() || is_tag() && empty( $query->query_vars['suppress_filters'] ) ) {
		$query->set( 'post_type', array( 'post', 'case' ));
		
		return $query;
	}
}
add_filter( 'pre_get_posts', 'wpm_add_custom_types' );

function wpm_add_custom_types( $query ) {

if( is_category() || is_tag() && empty( $query->query_vars['suppress_filters'] ) ) {

$query->set( 'post_type', array( 'post', 'case' ));

return $query;

}

add_filter( 'pre_get_posts', 'wpm_add_custom_types' );

Custom Post Type Taxonomy

06 Feb 2017