Solved it with add_meta_box in functions.php. Here is my code:
add_action( 'add_meta_boxes', 'my_custom_box' );
function my_custom_box(){
if ( function_exists('add_meta_box') ) {
add_meta_box( 'page_custom_menu','page-menu', 'page_custom_menu_box', 'page', 'side','high');
add_meta_box('page_custom_menu','page-menu', 'page_custom_menu_box', 'post', 'side', 'high');
}
}
function page_custom_menu_box(){
global $post;
if ( metadata_exists( 'post', $post->ID, 'page_menu' ) ) {
$menu_id = get_post_meta( $post->ID, 'page_menu', true );
}
$entries = get_terms( 'nav_menu', array( 'hide_empty' => false ) );
echo '<select class="postform" id="page_menu" name="page_menu"> ';
echo '<option value="">Select...</option> ';
foreach ($entries as $key => $entry){
$id = $entry->term_id;
$title = $entry->name;
if ( $id == $menu_id ){
$selected = "selected='selected'";
}else{
$selected = "";
}
echo"<option $selected value="". $id."">". $title."</option>";
}
echo '</select>';
}
add_action('save_post', 'save_postdata');
function save_postdata( $post_id ) {
global $post;
if( !isset($_POST['page_menu']) )
return;
$data = $_POST['page_menu'];
if(get_post_meta($post_id, 'page_menu') == "") {
add_post_meta($post_id, 'page_menu', $data, true);
}elseif($data != get_post_meta($post_id, 'page_menu', true)) {
update_post_meta($post_id, 'page_menu', $data);
}elseif($data == "") {
delete_post_meta($post_id, 'page_menu', get_post_meta($post_id, 'page_menu', true));
}
}
In header.php:
if( is_page() && get_post_meta( $post->ID, 'page_menu', true )!='' ){
global $post;
$menu_id = get_post_meta( $post->ID, 'page_menu', true );
wp_nav_menu( array( 'container_id' => 'submenu', 'menu' => $menu_id ) );
}elseif( is_single() && get_post_meta( $post->ID, 'page_menu', true )!='' ){
global $post;
$menu_id = get_post_meta( $post->ID, 'page_menu', true );
wp_nav_menu( array( 'container_id' => 'submenu', 'menu' => $menu_id ) );
}else{
//default menu
wp_nav_menu( array( 'container_id' => 'submenu', 'theme_location' => 'primary','menu_id'=>'web2feel' ,'menu_class'=>'sfmenu','fallback_cb'=> 'fallbackmenu' ) );
}