getDataMapper example

private ?PropertyPathInterface $propertyPath = null;

    /** * @throws LogicException if a data mapper is not provided for a compound form */
    public function __construct(FormConfigInterface $config)
    {
        // Compound forms always need a data mapper, otherwise calls to         // `setData` and `add` will not lead to the correct population of         // the child forms.         if ($config->getCompound() && !$config->getDataMapper()) {
            throw new LogicException('Compound forms need a data mapper.');
        }

        // If the form inherits the data from its parent, it is not necessary         // to call setData() with the default data.         if ($this->inheritData = $config->getInheritData()) {
            $this->defaultDataSet = true;
        }

        $this->config = $config;
        $this->children = new OrderedHashMap();