dosamigos\datepicker\DateRangePicker::init PHP Метод

    public function init()
    {
        parent::init();
        if (!$this->hasModel() && $this->nameTo === null || $this->hasModel() && $this->attributeTo === null) {
            // @codeCoverageIgnoreStart
            throw new InvalidConfigException("Either 'nameTo', or 'model' and 'attributeTo' properties must be specified.");
            // @codeCoverageIgnoreEnd
        }
        if ($this->size) {
            Html::addCssClass($this->options, 'input-' . $this->size);
            Html::addCssClass($this->optionsTo, 'input-' . $this->size);
            Html::addCssClass($this->containerOptions, 'input-group-' . $this->size);
        }
        Html::addCssClass($this->containerOptions, 'input-group input-daterange');
        Html::addCssClass($this->options, 'form-control');
        Html::addCssClass($this->optionsTo, 'form-control');
    }