如何使用php进行一段时间的短代码循环?

我是PHP的初学者,我一直在尝试创建一个函数,通过添加一个短代码来显示我的while循环。我知道add\u shortcode的语法要求在函数中返回,但我似乎无法让它在while循环中显示字符串。当我尝试返回字符串时,它只显示最后一个值,而不是循环。如有任何意见,将不胜感激!

function events_homepage() {
    global $connection;
    mysqli_select_db($connection);
    $query = ("SELECT * FROM events WHERE start_date >= CURDATE() ORDER BY start_date LIMIT 3");
    $result = $connection->query($query);
    while ($row = $result->fetch_assoc()) {
        $title = $row['title'];
        $start_date = date('M d, Y', strtotime($row['start_date']));
        $location = $row['location'];
        $link = $row['link'];
        $str = "<p class='events_homepage_date'>$start_date</p> <p class='events_homepage_title'><a href='$link' target='_blank'>$title</a></p> <p class='events_homepage_location'>$location</p>";
        echo $str;
    }
    return;
}
add_shortcode( 'events_homepage_shortcode', 'events_homepage' );