Magento2- Dynamic row system config store data in database but after save not display in backed

Question

My config file after save config data

After save data It also show error in console as there is no any field

after save data it does not give me unserialaize data my php file to render data in table is

<?php
        namespace Vendor\Module\Block\Adminhtml;

        use Magento\Config\Block\System\Config\Form\Field\FieldArray\AbstractFieldArray;
        use Magento\Framework\DataObject;
        use Magento\Framework\Exception\LocalizedException;
        use Vendor\Module\Block\Adminhtml\PaymentMethod;
        use Vendor\Module\Block\Adminhtml\UnitMethod;

        class Payment extends AbstractFieldArray
        {

            private $pymentRenderer;

            private $unitRenderer;


            protected function _prepareToRender()
            {
                $this->addColumn('paymentmethod', [
                    'label' => __('Payment Method'),
                    'renderer' => $this->getPaymentRenderer()
                ]);
                $this->addColumn('duration', ['label' => __('Duration'), 'class' => 'required-entry']);
                $this->addColumn('unit', [
                    'label' => __('Units'),
                    'renderer' => $this->getUnitRenderer()
                ]);
                $this->_addAfter = false;
                $this->_addButtonLabel = __('Add');
            }


            protected function _prepareArrayRow(DataObject $row): void
            {
                $options = [];

                $pm = $row->getPaymentMethod();
                $unit = $row->getUnitMethod();
                if ($pm !== null) {
                    $options['paymentmethod_' . $this->getPaymentRenderer()->calcOptionHash($pm)] = 'selected="selected"';
                    \Magento\Framework\App\ObjectManager::getInstance()->get('Psr\Log\LoggerInterface')->info(print_r($options,true));
                    $row->setData('paymentmethod', $options);
                }
                $options = [];
                if ($unit !== null) {
                    $options['unit_' . $this->getUnitRenderer()->calcOptionHash($unit)] = 'selected="selected"';
                    \Magento\Framework\App\ObjectManager::getInstance()->get('Psr\Log\LoggerInterface')->info(print_r($options,true));
                    $row->setData('unit', $options);
                }

            }


            private function getPaymentRenderer()
            {
                if (!$this->pymentRenderer) {
                    $this->pymentRenderer = $this->getLayout()->createBlock(
                        paymentmethod::class,
                        '',
                        ['data' => ['is_render_to_js_template' => true]]
                    );
                }
                return $this->pymentRenderer;
            }
            private function getUnitRenderer()
            {
                if (!$this->unitRenderer) {
                    $this->unitRenderer = $this->getLayout()->createBlock(
                        unitmethod::class,
                        '',
                        ['data' => ['is_render_to_js_template' => true]]
                    );
                }
                return $this->unitRenderer;
            }
        }

Answer 1

With reference to you console output, you need to modify your _prepareArrayRow function like this:

protected function _prepareArrayRow(DataObject $row): void
{
    $options = [];

    $pm = $row->getPaymentMethod();
    $unit = $row->getUnitMethod();
    if ($pm !== null) {
        $options['paymentmethod_' . $this->getPaymentRenderer()->calcOptionHash($pm)] = 'selected="selected"';
    }
    if ($unit !== null) {
        $options['unit_' . $this->getUnitRenderer()->calcOptionHash($unit)] = 'selected="selected"';

    }
    $row->setData('option_extra_attrs', $options);
}

Note: If you skip the label for dynamic field in system.xml, it won't save.

This is working on Magento 2.3.5 enterprise edition