How to get the first topic in a lesson in learndash

Question

I want to retrieve the first topic in a lesson in learndash and redirect it through it. But for some reason am not sure how to do it.

I checked the API and doesn't see any appropriate filter/hook for it.

Here is my code:

  function redirect_to_first_topic() {
// We only want to do this for Topics. But the below code can be adapted to work for Lessons
global $post;
$post_id = $post->ID;

if ( get_post_type( $post_id ) == 'sfwd-lessons' ) {
    $progress = learndash_get_course_progress( null, $post_id );
    $link = $progress['next'];

    $parent_lesson_id = learndash_get_setting( $post, 'topic' );
    $parent_lesson = get_post( $parent_lesson_id );
    var_dump($parent_lesson);
}

// Always return $link
// return $link;

}

add_action('wp', 'redirect_to_first_topic');

So basically what am doing here is getting the parent which is the lesson.

Answer 1

A bit late, but mb it will help someone else. You can see how to get 1. lesson of a course and go deeper if needed fe. first topic of first lesson and so on :

add_action( 'template_redirect', 'course_overview_redirect' );

function course_overview_redirect() {
global $post;

if ( ! empty( $post ) && $post->post_type == 'sfwd-courses' && ! empty( $post->ID ) ) {

    $lessons = learndash_get_course_lessons_list( $post->ID );

    if ( ! empty( $lessons ) ) {
        $lesson = array_shift( $lessons );

        if ( ! empty( $lesson ) ) {
            $url = get_permalink( $lesson[ "post" ]->ID );

            if ( ! empty( $url ) ) {   
                wp_redirect( esc_url( $url ) );  // And redirect if needed
                exit;
            }
        }
    }
}
}

Answer 2

You can add a button like this;

$args = array(
    'posts_per_page' => -1,
    'post_type' => 'sfwd-lessons', // you can change here to find topics : 'sfwd-topics'
    'suppress_filters' => true,
    'fields' => 'ids',
    'orderby' => 'menu_order', // ordering by menu_order will show lesson list, in their order in course. 
    'order' => 'ASC',
    // this meta query is used if you want to search a lesson under a course, or if you search for a topic which is in a course but not under a lesson                      
    'meta_query' => array(      
                 array(
                    'key'     => 'course_id',
                    'value'   => $course_id, // this is id of your course
                 )
    // if your topic is under a lesson than you should add lesson meta query
    // your meta query should be changed like below
    /* 
    'meta_query'     => array(
        'relation' => 'AND',
        array(
            'key'   => 'course_id',
            'value' => $course_id,
        ),
        array(
            'key'   => 'lesson_id',
            'value' => $lesson_id,
        ),
    ),
    */
            ),                  
    
);

$all_lessons = get_posts($args);    

$first_lesson = $all_lessons[0]; // taking directly first element of array  

$button_html = '<a href="' . esc_url( get_post_permalink( $first_lesson ) ) . '" class="button">' . __( 'Start the course', 'custom-text' ) . '</a>';