How to get Count of Lessons in a course in cakephp? - cakephp

Question

Thanks in advance!
I am new to CakePHP, and I am trying to get just count of lessons of course. I am using CakePHP with friendsofcake's crud.
$this->Crud->on('beforePaginate', function(\Cake\Event\Event $event) {
$query = $event->getSubject()->query;
$query->contain(['Lessons']);
});
with this code, I am getting all the lessons of the course, but I need only counts, because if a course having 50 lessons, why I should get all the lessons?
Output:-
App\Model\Entity\Course Object
(
[id] => 7
[language_id] => 2
[course_title] => test
[course_desc] =>
[audio_path] =>
[img_path] =>
[inappiosid] =>
[inappandroidid] =>
[sOrder] => 1
[lessons] => Array
(
[0] => App\Model\Entity\Lesson Object
(
[id] => 4
[course_id] => 7
[lesson_title] => test
[lesson_description] => test
[file_path] => test
[sOrder] => 1
[[new]] =>
[[accessible]] => Array
(
[course_id] => 1
[lesson_title] => 1
[lesson_description] => 1
[file_path] => 1
[sOrder] => 1
[course] => 1
)
)
)
[[new]] =>
[[accessible]] => Array
(
[language_id] => 1
[course_title] => 1
[course_desc] => 1
[audio_path] => 1
[img_path] => 1
[inappiosid] => 1
[inappandroidid] => 1
[sOrder] => 1
[language] => 1
[customer_orders] => 1
[lessons] => 1
)
)