Nette\Forms\Controls\ChoiceControl::loadHttpData PHP Method

    public function loadHttpData()
    {
        $this->value = $this->getHttpData(Nette\Forms\Form::DATA_TEXT);
        if ($this->value !== NULL) {
            if (is_array($this->disabled) && isset($this->disabled[$this->value])) {
                $this->value = NULL;
            } else {
                $this->value = key([$this->value => NULL]);
            }
        }
    }