Yii2 add rule based on condition - php

Question

I am building a website using PHP Yii2 Framework and dektrium\yii2-user extension for user authentication.
I want to ask the user for a captcha if the number of unsuccessful logins is over three, but by default the extension doesn't support this.
Now, I have overridden the extension's User and LoginForm model, and added the fields and checks required. However, I cannot figure out how to add a rule to make the captcha required only from the fourth attempt.
Is it possible to add rules dynamically? I have shown a simplified code view below and my comments where I need help. I will write the functions, just need help with the commented part.
<?php
namespace app\models\dektrium\user;
class LoginForm extends \dektrium\user\models\LoginForm
{
public $captcha;
public $need_captcha;
public function rules() {
$rules = parent::rules();
//This is how you'd normally add a rule, but this will require it for every login
//The following rule should be added from the login()
$rules[] = ['captcha', 'captcha', 'message' => 'Too many attempts. Captcha required.'];
$rules[] = ['need_captcha', 'boolean'];
return $rules;
}
public function login() {
$success = false;
$requireCaptcha = false;
if ($this->validate() && $this->user) {
if ($this->user->login_attempts > 3) {
//add rule here to require captcha
$requireCaptcha = true;
}
$success = !$requireCaptcha && $this->validateCaptcha() && $this->validateLogin();
if ($success) {
$this->user->updateAttributes(['last_login_at' => time()]);
}
}
return $success;
}
}
?>
EDIT:
If there is an 'optional' parameter converse to 'required', that'd suffice to. I can check for the captcha within my login().
EDIT 2:
I tried to use scenarios as follows, but the model is not loading the captcha value in the controller action, before doing the validation.
<?php
namespace app\models\dektrium\user;
class LoginForm extends \dektrium\user\models\LoginForm
{
public $captcha;
public $need_captcha;
public $login_count;
public function rules() {
$rules = parent::rules();
$rules[] = ['captcha', 'captcha', 'message' => 'Too many attempts. Captcha required.', 'on' => ['required_captcha']];
$rules[] = ['need_captcha', 'boolean'];
$rules[] = ['login_count', 'integer'];
return $rules;
}
public function login() {
$this->user = $this->finder->findUserByUsernameOrEmail(trim($this->login));
if($this->user && $this->user->login_count > 3) {
$this->scenario = 'required_captcha';
$this->need_captcha = true;
}
$success = parent::login();
if ($success) {
$this->user->login_count = 0;
$this->user->save();
} else {
$this->login_count++;
if ($this->user) {
$this->user->login_count++;
$this->user->save();
}
}
if ($this->login_count > 3) {
$this->scenario = 'required_captcha';
$this->need_captcha = true;
}
return $success;
}
}

Answer 1

Use
['field', 'required', 'when' => function($model) { return your_true_condition; } when setting up validation rules.
Condition can be something from session/cookie, like an integer that you will increment each time

Answer 2

So here's how I ended up doing this...
I used a scenario based rule and in the controller action, I set the scenario when the condition for which I needed captcha was true. In reality, the controller was also of any extension, so I had to do some supported controller mapping and set the scenario via an event.
My first attempts at doing this failed since I was setting the scenario during the validation function, but should have probably set it prior to doing so, where it worked.
<?php
namespace app\models\dektrium\user;
class LoginForm extends \dektrium\user\models\LoginForm
{
public $captcha;
public $need_captcha;
public $login_count;
public function rules() {
$rules = parent::rules();
$rules[] = ['captcha', 'required', 'on' => ['use_captcha']];
$rules[] = ['captcha', 'captcha', 'on' => ['use_captcha']];
$rules[] = ['need_captcha', 'boolean'];
$rules[] = ['login_count', 'integer'];
return $rules;
}
public function login() {
$success = true;
$this->user = $this->finder->findUserByUsernameOrEmail(trim($this->login));
if(!$this->need_captcha && $this->user && $this->user->login_count > 3) {
$this->need_captcha = true;
$success = false;
}
$success = $success && parent::login();
if ($success) {
$this->user->login_count = 0;
$this->user->save();
} else {
$this->login_count++;
if ($this->user) {
$this->user->login_count++;
$this->user->save();
}
if ($this->login_count > 2)
$this->need_captcha = true;
}
return $success;
}
}