Create new hasMany children from parent controller - cakephp

Question

I have two controllers "Events" and "Activities" and both have many "Attendees".
$this->hasMany('Attendees')
->setClassName('Attendees')
->setForeignKey('foreign_id')
->setConditions(array('Attendees.class' => 'Activity'))
->setDependent(true);
I am using a class and a foreign_id in my Attendees table to link them. I would like to create addAttendee() function in my ActivitiesController for example to add a new attendee, but I am not sure how to proceed.
public function addAttendee($id = null)
{
$activity = $this->Activities->get($id, ['contain' => ['Venues', 'Contacts']]);
if ($this->request->is('post'))
{
??
}
$this->set(compact('activity'));
}
I found some documentation on saving with association but not on creating new association.

Answer 1

You can create a new Attendee entity then link it to your $activity.
$data = ['first_name' => 'blah', 'last_name' => ... fields]);
$attendee = $this->Attendee->newEntity($data);
$this->Attendee->link($activity, [$attendee]);
source: https://api.cakephp.org/4.2/class-Cake.ORM.Association.HasMany.html#link()

Answer 2

I proceed this way. It's working but not sure if it's the right way to proceed ??
public function addAttendee($id)
{
$activity = $this->Activities->get($id, ['contain' => ['Venues', 'Contacts']]);
$attendee = $this->Activities->Attendees->newEmptyEntity();
if ($this->request->is('post'))
{
$attendee = $this->Activities->Attendees->patchEntity($attendee, $this->request->getData() + ['class' => 'retreat', 'foreign_id' => $id]);
if ($this->Activities->Attendees->save($attendee))
{
$this->Flash->success(__('The attendee has been saved.'));
return $this->redirect(['action' => 'view', $id]);
}
$this->Flash->error(__('The attendee could not be saved. Please, try again.'));
}
$this->set(compact('activity', 'attendee'));
}