framework/widgets/MaskedInput.php
public function init()
    {
        parent::init();
        if (empty($this->mask) && empty($this->clientOptions['alias'])) {
            throw new InvalidConfigException("Either the 'mask' property or the 'clientOptions[\"alias\"]' property must be set.");
        }
    }
public function init()
    {
        parent::init();
        if (empty($this->mask) && empty($this->clientOptions['alias'])) {
            throw new InvalidConfigException("Either the 'mask' property or the 'clientOptions[\"alias\"]' property must be set.");
        }
    }
Initializes the widget.

@throws InvalidConfigException if the "mask" property is not set.