CakePHP custom Validation rule checks unique field combination only on create - validation

Question

I have a Database with a User model. These Users should be unique by their name and birthday.
So I wrote a custom validation function called checkUnique
public function checkUnique($check){
$condition = array(
"User.name" => $this->data["User"]["name"],
"User.lastname" => $this->data["User"]["lastname"],
"User.birthday" => $this->data["User"]["birthday"]
);
$result = $this->find("count", array("conditions" => $condition));
return ($result == 0);
}
The validation rule in the model:
"name" => array(
"checkUnique" => array(
"rule" => array("checkUnique"),
"message" => "This User already exists.",
"on" => "create"
),
)
I have two problems.
The first: This validation rule also triggers on update action, implemented as
public function edit($id = null) {
if (!$this->User->exists($id)) {
throw new NotFoundException(__('Invalid User'));
}
if ($this->request->is(array('post', 'put'))) {
if ($this->User->save($this->request->data)) {
$this->Session->setFlash(__('Update done.'));
return $this->redirect(array('action' => 'index'));
} else {
$this->Session->setFlash(__('The user can't be saved.'));
}
} else {
$options = array('conditions' => array('User.' . $this->User->primaryKey => $id));
$this->request->data = $this->User->find('first', $options);
}
}
But I wrote "on" => "create", so why it triggers also on update?
The second problem:
If the validation rule only triggers on create, how can I manage, to trigger an validation error, if someone change the name, lastname and birthday like an other user in the Database? Then the unique validation rule should be triggered.

Answer 1

Remove the 'on' => 'create'. (You want to validate in both events).
Modify your custom validation rule to this
public function checkUnique() {
$condition = array(
"User.name" => $this->data["User"]["name"],
"User.lastname" => $this->data["User"]["lastname"],
"User.birthday" => $this->data["User"]["birthday"]
);
if (isset($this->data["User"]["id"])) {
$condition["User.id <>"] = $this->data["User"]["id"];
//your query will be against id different than this one when
//updating
}
$result = $this->find("count", array("conditions" => $condition));
return ($result == 0);
}