Symfony2 form collections limit - forms

Question

I have a Course entity, which has many CourseSessions. CourseSession can be active or passed.
How can I render only active CourseSessions and save relations with the passed CourseSessions on the Course edit page?
Now I render all CourseSessions but when CourseSession counts more than 50, the page renders very slow.
Can anyone help me?
UPDATE 1:
class CourseType {
$builder->add('sessions', 'collection', array(
'label' => false,
'type' => new CourseSessionType(), // <- here I want to pass only active Sessions
'allow_add' => true,
'allow_delete' => true,
'prototype' => true,
'prototype_name' => '__name__'
))
}
class CourseSessionType {
// multiple CourseSession fields
}
// Course edit page
<div id="courseSessions" data-prototype="{{macros.course_session_prototype(form.sessions, 'Remove Session', true)|escape }}">
{% do form.sessions.setRendered %}
{% for widget in form.sessions.children %}
{{ macros.course_session_prototype(widget, 'Remove Session', false) }}
{% endfor %}
</div>
UPDATE 2:
How can I map my 'type' => new CourseSessionType() with getActiveCourseSessions() and setActiveCourseSessions()? I think it will help me.

Answer 1

try to set the name of the field accordingly to the method to map using active_course_sessions or shorter if you name your methods Course::getActiveSessions() and Course::setActiveSessions() it could be done like this :
class CourseType {
$builder->add('active_sessions', 'collection', array(
'label' => false,
'type' => new CourseSessionType(),
'allow_add' => true,
'allow_delete' => true,
'prototype' => true,
'prototype_name' => '__name__'
));
}

Answer 2

I'm glat to tell you that I found the solution!
I added in my Course entity a $showOnlyActiveSessions property and changed getSessions() method
class Course
{
/**
* Show only active sessions flag
* #var bool
*/
private $showOnlyActiveSessions = false;
// other properties
/**
* Get course sessions
* #return CourseSession []
*/
public function getSessions()
{
$sessions = $this->sessions;
if ($this->getShowOnlyActiveSessions()) {
return array_filter($sessions->toArray(), function($session) {
return !$session->isPast();
});
}
return $this->sessions;
}
/**
* #return bool
*/
public function getShowOnlyActiveSessions()
{
return $this->showOnlyActiveSessions;
}
/**
* #param bool $boolValue
*/
public function setShowOnlyActiveSessions($boolValue)
{
$this->showOnlyActiveSessions = $boolValue;
}
}
and now, when I need to get only active sessions i do the following in my controller:
public function editAction(Request $request, Course $course)
{
$course->setShowOnlyActiveSessions(true);
$editForm = $this->createEditForm($course);
$editForm->handleRequest($request);
if ($editForm->isValid()) {
// handle and persist form
}
return $this->redirectToRoute('course_list');
}
I hope it'll be helpful for somebody.