Creating a custom client-side validation

In the Writing your own validators recipe, we created a standalone validator. In this recipe, we will modify a validator to create extra client-side validation, which also checks the number of words.

Getting ready

Create a new application by using the Composer package manger, as described in the official guide at http://www.yiiframework.com/doc-2.0/guide-startinstallation.html.

How to do it...

1. Create @app/components/WordsValidator.php as follows:

   <?php
   namespace app\components;
   use yii\validators\Validator;
   class WordsValidator extends Validator
   {
       public $size = 50;
       public $message = 'The number of words must be less than {size}';
       public function validateValue($value)
       {
           preg_match_all('/(\w+)/i', $value, $matches);
           if (count($matches[0]) > $this->size) {
               return [$this->message, ['size' => $this->size]];
           }
       }
       public function clientValidateAttribute($model, $attribute, $view)
    ...