How to get and set custom field of customer_group table Magento 2

Question

I create new extention and add some columns in customer_group table. but i can't get/set custom field.

namespace [NameSpace]\[Extension]\Block\Adminhtml\Group\Edit;

use Magento\Customer\Controller\RegistryConstants;
use Magento\Tax\Model\TaxClass\Source\Product as TaxProduct;

class Form extends \Magento\Customer\Block\Adminhtml\Group\Edit\Form
{

    protected $_taxProduct;

    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Framework\Registry $registry,
        \Magento\Framework\Data\FormFactory $formFactory,
        \Magento\Tax\Model\TaxClass\Source\Customer $taxCustomer,
        \Magento\Tax\Model\TaxClass\Source\Product $taxProduct,
        \Magento\Tax\Helper\Data $taxHelper,
        \Magento\Customer\Api\GroupRepositoryInterface $groupRepository,
        \Magento\Customer\Api\Data\GroupInterfaceFactory $groupDataFactory,
        array $data = []
    ) {
        $this->_taxCustomer     = $taxCustomer;
        $this->_taxProduct      = $taxProduct;
        $this->_taxHelper       = $taxHelper;
        $this->_groupRepository = $groupRepository;
        $this->groupDataFactory = $groupDataFactory;
        parent::__construct($context, $registry, $formFactory, $taxCustomer, $taxHelper, $groupRepository, $groupDataFactory, $data);
    }

    protected function _prepareLayout()
    {
        parent::_prepareLayout();
        $form = $this->getForm();
        $groupId = $this->_coreRegistry->registry(RegistryConstants::CURRENT_GROUP_ID);
        /** @var \Magento\Customer\Api\Data\GroupInterface $customerGroup */

        if ($groupId === null) {
            $customerGroup = $this->groupDataFactory->create();
        } else {
            $customerGroup      = $this->_groupRepository->getById($groupId);
        }

        $fieldset = $form->addFieldset('tax_classes', ['legend' => __('Tax Classes')]);

        $fieldset->addField(
            'tax_classes_shipping_tax_class',
            'select',
            [
                'name' => 'tax_classes_shipping_tax_class',
                'label' => __('Tax Class for Shipping'),
                'title' => __('Tax Class for Shipping'),
                'class' => '',
                'required' => false,
                'values' => $this->_taxProduct->toOptionArray(),
            ]
        );

        if($this->_backendSession->getCustomerGroupData()) {
            $form->addValues($this->_backendSession->getCustomerGroupData());
            $this->_backendSession->setCustomerGroupData(null);
        } else {
            /* print_r($customerGroup->getData());exit; */
            $form->addValues($customerGroup->getData());
        }
    }
}

namespace [NameSpace]\[Extension]\Controller\Adminhtml\Group;

class Save extends \Magento\Customer\Controller\Adminhtml\Group\Save
{
    /**
     * Create or save customer group.
     *
     * @return \Magento\Backend\Model\View\Result\Redirect|\Magento\Backend\Model\View\Result\Forward
     */
    public function execute()
    {
        $taxClass = (int)$this->getRequest()->getParam('tax_class');

        /** @var \Magento\Customer\Api\Data\GroupInterface $customerGroup */
        $customerGroup = null;
        if ($taxClass) {
            $id = $this->getRequest()->getParam('id');
            $resultRedirect = $this->resultRedirectFactory->create();
            try {
                if ($id !== null) {
                    $customerGroup = $this->groupRepository->getById((int)$id);
                } else {
                    $customerGroup = $this->groupDataFactory->create();
                }
                $customerGroupCode = (string)$this->getRequest()->getParam('code');
                if (empty($customerGroupCode)) {
                    $customerGroupCode = null;
                }

                $customerGroup->setCode($customerGroupCode);
                $customerGroup->setTaxClassId($taxClass);
                $data   = $this->getRequest()->getParams();
                $customerGroup->setData('tax_classes_shipping_tax_class',1);
                $this->groupRepository->save($customerGroup);

                $this->messageManager->addSuccess(__('You saved the customer group.'));
                $resultRedirect->setPath('customer/group');
            } catch (\Exception $e) {
                $this->messageManager->addError($e->getMessage());
                if ($customerGroup != null) {
                    $this->storeCustomerGroupDataToSession(
                        $this->dataObjectProcessor->buildOutputDataArray(
                            $customerGroup,
                            '\Magento\Customer\Api\Data\GroupInterface'
                        )
                    );
                }
                $resultRedirect->setPath('customer/group/edit', ['id' => $id]);
            }
            return $resultRedirect;
        } else {
            return $this->resultForwardFactory->create()->forward('new');
        }
    }
}

I try

$customerGroup->getData() or  $customerGroup->getCustomField() 

and

$customerGroup->setData('custom_field',1); 
        $this->_groupRepository->save($customerGroup); 

but fail.

Answer 1

Magento till use Magic setter & getter method for save data of model.

namespace [YourNameSpace];

..... 

use Magento\Customer\Api\Data\GroupInterface;

...

class [Your_Class] extends [Your_Extend] {
 protected $groupRepository;
 public function __construct(   ....
     GroupRepositoryInterface $groupRepository,     ......
 ) {    .....   
     parent::__construct(
        .....
        $groupRepository,
        .......
     );     
     $this->groupRepository = $groupRepository;
 }

 public function saveCustomfield()
 {  
    $id = 'Customer_Group_id';       
    $customerGroup = $this->groupRepository->getById((int)$id);

    $customerGroup->setData('fieldName',$your_Valur);

    $this->groupRepository->save($customerGroup->getCode());    
 }  
}