This its a password strength validator, with ajax request for checking the password field.

First create a validator in lib/validators/sfPasswordStrengthValidator.class.php

<?php
class sfPasswordStrengthValidator extends sfValidator
{
    public function execute (&$value, &$error)
    {
        $weakness = $this->Password_Strength($value);
 
        if($weakness==1) {
            $error = $this->getParameter('strength_error');
            return false;
        }
 
        return $weakness;
    }
 
    public function initialize ($context, $parameters = null)
    {
        // Initialize parent
        parent::initialize($context);
 
        // Set default parameters value
        $this->setParameter('strength_error', 'Weak password');
 
        // Set parameters
        $this->getParameterHolder()->add($parameters);
 
        return true;
    }
        // Thanks for: Alix Axel Weblog
    // URL: http://www.alixaxel.com/wordpress/wp-content/2007/06/Password_Strength.phps
    function Password_Strength($password, $username = null)
    {
        if (!empty($username))
        {
            $password = str_replace($username, '', $password);
        }
 
        $strength = 0;
        $password_length = strlen($password);
 
        if ($password_length < 5)
        {
            return $strength;
        }
 
        else
        {
            $strength = $password_length * 4;
        }
 
        for ($i = 2; $i <= 4; $i++)
        {
            $temp = str_split($password, $i);
 
            $strength -= (ceil($password_length / $i) - count(array_unique($temp)));
        }
 
        preg_match_all('/[0-9]/', $password, $numbers);
 
        if (!empty($numbers))
        {
            $numbers = count($numbers[0]);
 
            if ($numbers >= 3)
            {
                $strength += 5;
            }
        }
 
        else
        {
            $numbers = 0;
        }
 
        preg_match_all('/[|!@#$%&*\/=?,;.:\-_+~^¨\\\]/', $password, $symbols);
 
        if (!empty($symbols))
        {
            $symbols = count($symbols[0]);
 
            if ($symbols >= 2)
            {
                $strength += 5;
            }
        }
 
        else
        {
            $symbols = 0;
        }
 
        preg_match_all('/[a-z]/', $password, $lowercase_characters);
        preg_match_all('/[A-Z]/', $password, $uppercase_characters);
 
        if (!empty($lowercase_characters))
        {
            $lowercase_characters = count($lowercase_characters[0]);
        }
 
        else
        {
            $lowercase_characters = 0;
        }
 
        if (!empty($uppercase_characters))
        {
            $uppercase_characters = count($uppercase_characters[0]);
        }
 
        else
        {
            $uppercase_characters = 0;
        }
 
        if (($lowercase_characters > 0) && ($uppercase_characters > 0))
        {
            $strength += 10;
        }
 
        $characters = $lowercase_characters + $uppercase_characters;
 
        if (($numbers > 0) && ($symbols > 0))
        {
            $strength += 15;
        }
 
        if (($numbers > 0) && ($characters > 0))
        {
            $strength += 15;
        }
 
        if (($symbols > 0) && ($characters > 0))
        {
            $strength += 15;
        }
 
        if (($numbers == 0) && ($symbols == 0))
        {
            $strength -= 10;
        }
 
        if (($symbols == 0) && ($characters == 0))
        {
            $strength -= 10;
        }
 
        if ($strength < 0)
        {
            $strength = 0;
        }
 
        if ($strength > 100)
        {
            $strength = 100;
        }
 
        return $strength;
    }
}
 

Then in your view template use:

<?php echo observe_field('password', array(
                          'update'   => 'passwordStatus',
                          'url'      => 'sfGuardAuth/checkPasswordStrength',
                          'with' => "'id='+encodeURIComponent($('password').value)",
                          'loading'=>"Element.show('indicator_passwordstatus')",
                          'complete'=>"Element.hide('indicator_passwordstatus');Element.show('passwordStatus');",
                      )) ?>
 

That code will monitor changes at password input field, and submit the updated value to the defined route.

Then add the following to your actions file:

public function executeCheckPasswordStrength() {
        $password = $this->getRequestParameter('id');
        $strengthValidator = new sfPasswordStrengthValidator();
        $strengthValidator->initialize($this->getContext());
        $error='none';
        $score = $strengthValidator->execute($password,$error);
        if(!$score)
        return $this->renderText('too short');
        if($score < 20) {
            return $this->renderText('not weak');
        } else if($score < 50) {
            return $this->renderText('relevant');
        } else {
            return $this->renderText('strong');
        }
 
        return true;
    }
 

Cheers