Email Validation in cakephp Model

I have the below setup of validation rules. For some reason, 'on' => 'create' block doesn't work. The conditions to be implemented are standard create / modify regarding email. Also, in edit section, I'm getting the error from 'on' => 'create' block.

How to validate the email? I'm using CakePHP v 2.6.1.

public $validate = array(
    'email' => array(
        'required' => array(
            'rule' => array('email'),
            'message' => 'Kindly provide your email for verification.'
        ),
        'maxLength' => array(
            'rule' => array('maxLength', 255),
            'message' => 'Email cannot be more than 255 characters.'
        ),
        'editunique' => array(
            'rule' => array('editunique'),
            'message' => 'Provided Email address already exists.',
            'on' => 'update'
        ),
        'unique' => array(
            'rule' => 'isUnique',
            'message' => 'Provided Email already exists.',
            'on' => 'create'
        )
    )
);


public function editunique($email) {
    // email should be one and of the logged in user only.
    if ($this->find('count', array(
        'conditions' => array(
            $this->alias . '.id <>' => $this->data[$this->alias]['id'],
            $this->alias . '.email' => $email
        )
    )) > 1) {
        return false;
    }

}

Also, I'm not getting the $this->data[$this->alias]['id'] value.

My Controller has the following section:

if ($this->Client->hasAny(array('Client.id' => base64_decode(trim($this->request->query['client_id']))))){
            if ( $this->request->is('ajax') && $this->request->is('post') ){
                $this->Client->create();
                $this->Client->id = base64_decode(trim($this->request->query['client_id']));
                $this->Client->set($this->request->data);
                // validate
                if($this->Client->validates()) {
                    // save the data after validation
                    if($this->Client->save($this->request->data)){
                     }
                 }
             }
        }

I think you are misunderstanding what Cake's isUnique rule checks for and as a result over complicating things. Cake defines isUnique as:-

The data for the field must be unique, it cannot be used by any other rows

When it checks if a value is unique it is smart enough to exclude existing data of the current row (which appears to be what you are attempting to do with your editunique rule).

So you just need your validation rules to look like:-

public $validate = array(
    'email' => array(
        'required' => array(
            'rule' => array('email'),
            'message' => 'Kindly provide your email for verification.'
        ),
        'maxLength' => array(
            'rule' => array('maxLength', 255),
            'message' => 'Email cannot be more than 255 characters.'
        ),
        'unique' => array(
            'rule' => 'isUnique',
            'message' => 'Provided Email already exists.'
        )
    )
);

This removes the editunique rule and drops the on condition of your unique rule.