//控制器页面
//Instantiate the model class
$model = new \app\models\MyForm();

// populate model attributes with user inputs
$model->load(\Yii::$app->request->post());
//validate the date being submitted the end user
if ($model->validate()) {
    // all inputs are valid
} else {
// validation failed, we can access the errors using     $error property as:
    $errors = $model->errors;
}

//验证处理
use yii\base\Model;

class MyForm extends Model
{
    public $username;
    public $email;

    public function rules()
    {
        return [
            // an inline validator defined as the model method validateUsername()
            ['username', 'validateUsername'],

            // an inline validator defined as an anonymous function
            ['email', function ($attribute, $params) {
                if (!filter_var($this->$attribute, FILTER_VALIDATE_EMAIL)) {
                  $this->addError($attribute, 'The email format is invalid!');
                }
            }],
        ];
    }

    public function validateUsername($attribute, $params)
    {
        if (preg_match('/[^a-z])/i', $this->$attribute)) {
             $this->addError($attribute, 'Username should only contain alphabets');
        }
        if ( ! preg_match('/^.{3,8}$/', $this->$attribute) ) {
             $this->addError($attribute, 'Username must be bwtween 3 to 8 characters.');
        }
    }
}