Change default category

Hi,
you can set default value for advert_category field by adding the code below in your theme functions.php file

add_action( "adverts_form_bind", "default_value_for_adverts_add", 10, 2 );
function default_value_for_adverts_add( $form, $data ) {
    if( ! isset( $data['advert_category'] ) ) {
        $form->set_value( "advert_category", 25 );
    }
    return $form;
}

Just replace 25 with actual ID (numeric) of the taxonomy you would like to use as a default.

Ohh ok, in this case you will need to use a different code

add_filter( "adverts_form_load", "single_select_advert_category" );
function single_select_advert_category( $form ) {
  if( $form['name'] != "advert" ) {
    return $form;
  }
  foreach( $form["field"] as $key => $field ) {
    if( $field["name"] == "advert_category" ) {
        $form["field"][$key]["empty_option"] = true;
        $form["field"][$key]["max_choices"] = 1;
        $form["field"][$key]["validator"] = array();
        $form["field"][$key]["validator"][] = array( 
            "name" => "max_choices",
            "params" => array( "max_choices" => 1 )
        );
    }
  }
  return $form;
}