Symfony\Component\Form\Field::updateFromObject PHP Method

    public function updateFromObject(&$objectOrArray)
    {
        // TODO throw exception if not object or array
        if ($this->propertyPath !== null) {
            $this->setData($this->propertyPath->getValue($objectOrArray));
        } else {
            // pass object through if the property path is empty
            $this->setData($objectOrArray);
        }
    }