form.php
public function getValue(SelectorInterface $selector)
    {
        for ($i = 0, $count = count($this->widgets); $i < $count; $i++) {
            if ($selector->isMatch($this->widgets[$i])) {
                return $this->widgets[$i]->getValue();
            }
        }
        foreach ($this->buttons as $button) {
            if ($selector->isMatch($button)) {
                return $button->getValue();
            }
        }

        return;
    }
public function getValue(SelectorInterface $selector)
    {
        for ($i = 0, $count = count($this->widgets); $i < $count; $i++) {
            if ($selector->isMatch($this->widgets[$i])) {
                return $this->widgets[$i]->getValue();
            }
        }
        foreach ($this->buttons as $button) {
            if ($selector->isMatch($button)) {
                return $button->getValue();
            }
        }

        return;
    }
Extracts current value from form.

@param $selector Criteria to apply.

@return string/array Value(s) as string or null if not set.