validators\EachValidator $rule

Definition of the validation rule, which should be used on array values. It should be specified in the same format as at \yii\validators\yii\base\Model::rules(), except it should not contain attribute list as the first element. For example:

['integer']
['match', 'pattern' => '/[a-z]/is']

Please refer to \yii\validators\yii\base\Model::rules() for more details.