WordPress：如何在Customizer中使用活动回调

Question

In my theme, I set up 2 options use Theme Customization API, the code snippet below.

I want to display the radio option when the checkbox is true, when the checkbox is false, the radio hidden. I try to use active_callback，but not working. So, How can achieve this function?

Thanks!

    // Related Post.
    $wp_customize->add_setting('_related_post', array(
        'capability' => 'edit_theme_options',
        'default' => 0,
        'transport' => 'postMessage',
    ));

    $wp_customize->add_control('_related_post', array(
        'settings'      => '_related_post',
        'label'         => __('Display Related Posts', 'typenow'),
        'section'       => '_theme_options',
        'type'          => 'checkbox',
        'priority'      => 30,
    ));
    
    // Related Post Num.
    
        $wp_customize->add_setting('_related_post_num', array(
        'capability' => 'edit_theme_options',
        'default' => '2',
        'transport' => 'postMessage',
    ));

    $wp_customize->add_control('_related_post_num', array(
        'settings'      => '_related_post_num',
        'label'         => __('Related Posts Number', 'typenow'),
        'section'       => '_theme_options',
        'type'          => 'radio',
        'priority'      => 35,
        'choices'       => array (
                            '2'  => __('Two posts', 'typenow'),
                            '4' => __('Four posts', 'typenow'),
                            ),
    ));

</div>

Answer 1

The solution:

$wp_customize->add_control('_related_post_num', array(
    'settings'      => '_related_post_num',
    'label'         => __('Related Posts Number', 'typenow'),
    'section'       => '_theme_options',
    'type'          => 'radio',
    'priority'      => 35,
    'choices'       => array (
                        '2'  => __('Two posts', 'typenow'),
                        '4' => __('Four posts', 'typenow'),
                        ),
    'active_callback' => function(){
        return get_theme_mod( '_related_post', false );
    },
));