How to create WordPress widget using custom menu select

Question

I'm creating a custom widget for WordPress but am wanting to use the same select menu as the default Custom Menu widget does. So far what I have works except the selected menu isn't being saved or displayed on the frontend. Any help or direction with this is appreciated. Thanks.

For brevity, I've removed extra widget options, so this is basically going to look very close to the Custom Menu widget:

class kedc_mini_sitemap extends WP_Widget {

/*constructor*/
function kedc_mini_sitemap() {
    parent::WP_Widget(false, $name = 'Mini Sitemap');
}

/**/
function widget($args, $instance) {
    extract( $args );

    // widget options
    $title = apply_filters('widget_title', $instance['title']);
    $nav_menu1 = ! empty( $instance['nav_menu'] ) ? wp_get_nav_menu_object( $instance['nav_menu'] ) : false;
    $checkbox = $instance['checkbox'];

    echo $before_widget;    

    if ($title) {
        echo $before_title . $title . $after_title;
    }

    if ($nav_menu1) {
        echo wp_nav_menu( array( 'fallback_cb' => '', 'menu' => $nav_menu1 ) );
    }


    if ($checkbox == true) {
        echo 'This message is displayed if our checkbox is checked.';
    }

    echo $after_widget;
}

/* saves options chosen from the widgets panel */
function update($new_instance, $old_instance) {
    $instance = $old_instance;
    $instance['title'] = strip_tags($new_instance['title']);
    $instance['nav_menu'] = (int) $new_instance['nav_menu'];
    $instance['checkbox'] = strip_tags($new_instance['checkbox']);
    return $instance;
}

/* display widget in widgets panel */
function form($instance) {  

    $title = esc_attr($instance['title']);
    $nav_menu1 = isset( $instance['nav_menu'] ) ? $instance['nav_menu'] : '';
    $checkbox = esc_attr($instance['checkbox']);

    $menus1 = get_terms( 'nav_menu', array( 'hide_empty' => false ) );

    ?>

    <p>
        <label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Widget Title:'); ?></label>
        <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" />
    </p>

    <p>
        <label for="<?php echo $this->get_field_id('nav_menu'); ?>"><?php _e('Select Menu:'); ?></label>
        <select id="<?php echo $this->get_field_id('nav_menu'); ?>" name="<?php echo $this->get_field_name('nav_menu'); ?>">
            <?php
                foreach ( $menus1 as $menu1 ) {
                    echo '<option value="' . $menu1->term_id . '"'
                        . selected( $nav_menu, $menu1->term_id, false )
                        . '>'. $menu1->name . '</option>';
                }
            ?>
        </select>
    </p>

    <p>
        <input id="<?php echo $this->get_field_id('checkbox'); ?>" name="<?php echo $this->get_field_name('checkbox'); ?>" type="checkbox" value="1" <?php checked( '1', $checkbox ); ?>/>
        <label for="<?php echo $this->get_field_id('checkbox'); ?>"><?php _e('Do you want this to display as 2 columns?'); ?></label>
    </p>

    <?php
}

}

// register widget
add_action('widgets_init', create_function('', 'return register_widget("kedc_mini_sitemap");'));

Answer 1

You have a typo in the form() function: $nav_menu1 and $nav_menu.

Use more meaningful, strict and descriptive names for your variables. For example, $menus1 could be called $get_nav_menus.

Use a good IDE, like NetBeans or similar, and check the WordPress Coding Standards Handbook.

Oh, yes, your code is dumping PHP Notices, always develop with WP_DEBUG enabled.