CakePHP 3 - beforeSave callback not working on edit - cakephp

Question

I have a beforeSave-callback which is called just fine whenever I create a new entity. However when I am editing, it's not called at all.
Could not find anything in the documentation that could be helpful.
Here's my edit function:
public function edit($id = null) {
if (!$id) {
throw new NotFoundException(__('Invalid article'));
}
$article = $this->Articles->get($id);
if ($this->request->is(['post', 'put'])) {
$this->Articles->patchEntity($article, $this->request->data);
if ($this->Articles->save($article)) {
$this->Flash->success(__('Your article has been updated.'));
return $this->redirect(['action' => 'index']);
}
$this->Flash->error(__('Unable to update your article.'));
}
$this->set('article', $article);
}

Answer 1

The beforeSave function will be triggered only if the data you post/edit is modified.
//triggers only if an entity has been modified
public function beforeSave(Event $event, Entity $entity)
{
if($entity->isNew()) {
//on create
} else {
//on update
}
}

Answer 2

I also had the problem that the tutorial got stuck on this point, but I used the bin/cake bake command to autogenerate the ArticlesTable code and it added this validator:
$validator
->scalar('slug')
->maxLength('slug', 191)
/*->requirePresence('slug', 'create')*/
->notEmptyString('slug')
->add('slug', 'unique', ['rule' => 'validateUnique', 'provider' => 'table']);
When I commented the requirePresence() it solved this issue for me. If you have requirePresence('fieldName', 'create') for validation, you will get an error if you don't have that field on a post when creating the new Article entity.

Answer 3

Yes, your need use Event and Entity object:
check this example:
// src/Model/Table/ArticlesTable.php
use Cake\Event\Event;
use Cake\ORM\Entity;
public function beforeSave(Event $event, Entity $entity) {
if ($entity->isNew()) {
return true;
}
// edit code
}

Answer 4

Another way to write the same code:
public function beforeSave(\Cake\Event\Event $event, \Cake\ORM\Entity $entity, \ArrayObject $options){
if($entity->isNew()) {
// on create
} else {
// on update
}
}