WordPress Search Filters

Try these snippets in your functions.php to filter wordpress search

RemoveWordpress pages From Search Results

function cp_remove_pages_from_search() {
global $wp_post_types;
$wp_post_types['page']->exclude_from_search = true;
}
add_action('init', 'cp_remove_pages_from_search');

Remove WordPress category From Search Results

add_filter( 'pre_get_posts', 'cp_filter_search' );
function cp_filter_search( $query ) {
if ( $query->is_search && !is_admin() )
$query->set( 'cat','-3' );
// 3 is the category id
return $query;
}

To exclude custom post type

function remove_portfolio_search() {
	global $wp_post_types;
	$wp_post_types['dt_portfolio']->exclude_from_search = true;
}
add_filter('pre_get_posts','remove_portfolio_search');

To exclude some specific post

add_filter( 'pre_get_posts', 'cp_filter_search' );
function cp_filter_search( $query ) {
	if ( $query->is_search && !is_admin() )
	$query->set( 'post__not_in', array(68,11) ); //68,11 are ids of the posts to exclude
	
	return $query;
}

To exclude custom post type category

add_filter( 'pre_get_posts', 'cp_filter_search' );
 
function cp_filter_search( $query ) {
	if ( $query->is_search && !is_admin() ) {
    //Define the tax_query
    $taxquery = array(
      array(
        'taxonomy' => 'dt_portfolio_category', // also try lower case, remember a taxonomy name must be in lowercase
        'field' => 'slug',
        'terms' => array( 'projects-2' ), //slug of the portfolio category
        'operator' => 'NOT IN'
      )
    );
      
	  $query->set('tax_query', $taxquery );
   
  }
}

Limit search to a specific post type

function searchfilter($query) {

    if ($query->is_search && !is_admin() ) {
        $query->set('post_type',array('dt_portfolio'));
    }

return $query;
}

add_filter('pre_get_posts','searchfilter');