Define and access virtual properties in cakePHP - where and how? - cakephp

Question

In an application a lecture hasMany slides and a slide belongsTo a lecture. When the index function of lecture is called we would like to add a column which displays the amount off slides belonging to a certain lecture.
I tried to define this as as a $virtualFields in the lecture model like this:
public $virtualFields = array(
'slides_amount' => 'SELECT COUNT(*) AS `count` FROM `eflux`.`slides` AS `Slide` LEFT JOIN `eflux`.`lectures`
AS `Lecture` ON (`Slide`.`lecture_id` = `Lecture`.`id`)
WHERE lecture_id = \''.$id.'\'')';
The problem is that I am not able to access the current $id of the object and therefore MySQL returns an error.
My next try was to use the controller for this:
$lectures = $this->Lecture->findByCourseId($course_id);
for ($i = 0; $i < count($lectures); $i++) {
$slide_amount = $this->Lecture->Slide->find('count', array('conditions' => 'lecture_id = \' '.$id.'\''));
$slide_amounts[$i] = $slide_amount;
}
I was also not able to access the id of the current $lecture-object to determin the amount of slides belonging to that lecture.
Finally I did it in the view:
for ($i = 0; $i < count($slides_helper); $i++) {
if ($slides_helper[$i]['slides']['lecture_id'] == $lecture['Lecture']['id']) {
echo $slides_helper[$i][0]['count'];
}
}?>
Only here I could acces the id of the current object or the $lectures array. But I feel that the view is not the place to handle this.
What is best practice to achieve this goal?

Answer 1

in your controller, you can try:
$lectures = $this->Lecture->find('all', array('conditions'=>array('Lecture.course_id'=>$course_id)));
foreach ($lectures as &$lecture){
$lecture['Lecture']['slide_count'] = count($lecture['Slide']);
}
$this->set('lectures', $lectures);
and then access the count in your view with
foreach ($lectures as $lecture){
echo $lecture['Lecture']['slide_count'];
}
The code might not be exact... you can help us give more accurate code by pasting the results of the following code:
Place this in your controller:
$lectures = $this->Lecture->find('all', array('conditions'=>array('Lecture.course_id'=>$course_id)));
pr($lectures);
EDIT FOR PAGINATION:
Something like this might work for your pagination
$this->paginate['conditions'] = array('Lecture.course_id'=>$course_id);
$this->paginate['limit'] = '10';
$lectures = $this->paginate('Lecture');
//PERFORM THE LOOP TO ADD SLIDE COUNT
$this->set('lectures', $lectures);