Why Yii2 captcha can't through the verification On the client side?

Question

I am using Yii2 admin Module, the captcha image is shown on the form. After I input the verifycode, tips always shown the error message on the client side, but I'm sure it was entered correctly. Then I view the source code, I found I didn't set the attribute captchaAction (\yii\captcha\CaptchaValidator) correctly, the default value of captchaAction is site/captcha, but my controller is app\modules\admin\controllers\PublicController, I think that the value of captchaAction should be admin/public/captcha, but how to set it ?

The following is my view page code:

<?= $form->field($model, 'verifyCode')->widget(Captcha::className(), [
    'template' => '<div class="row"><div class="col-lg-4">{image}</div> &nbsp;<div class="col-lg-7">{input}</div></div>',
    'captchaAction' => 'public/captcha',
 ]); ?>

Here is my controller：

public function actions()
{
    return [
        'error' => [
            'class' => 'yii\web\ErrorAction',
        ],
        'captcha' => [
            'class' => 'yii\captcha\CaptchaAction',
            'fixedVerifyCode' => YII_ENV_TEST ? 'testme' : null,
            'minLength' => 3,
            'maxLength' => 5,
        ],
    ];
}
public function actionLogin()
{
    $model = new LoginForm();
    if ( Yii::$app->request->isPost ) {
        # code ...
    } else {
        return $this->render('login', [
            'model' => $model,
            'title' => Yii::$app->params['adminLogin'],
        ]);
    }
}

Answer 1

Careful with form which is validated by AJAX. Captcha of Yii will be reload if you validate by Ajax. So with this case, we can solve with two option:

1. Disable ajaxValidation, enable clientValidation. Such as: signup form

$form = ActiveForm::begin([
    'id'                     => 'registration-form',
    'enableAjaxValidation'   => true,
    'enableClientValidation' => false
]);

2. Override function validate of CaptchaAction, don't getVerifyCode through AJAX.

if(\Yii::$app->request->isAjax == false) {
    $this->getVerifyCode(true);
}