How can we add custom grid at customer group edit form inside a fieldset?

Question

How Can we add custome grid with custome collection on customer group edit form in fieldset.

Answer 1

After adding preference for the class

<preference for="Magento\Customer\Block\Adminhtml\Group\Edit\Form" type="Vendor\Module\Block\Adminhtml\PathToFile" />

Add below code in it

$fieldset->addType(
    'some_thing',
    'Vendor\Module\Block\Adminhtml\Renderer\ClassName'
);
$field = $fieldset->addField(
    'some_thing',
    'some_thing',
    [
        'name' => 'some_thing',
        'label' => __('Something'),
        'title' => __('Something')
    ]
);

In your Vendor/Module/Block/Adminhtml/Renderer/Classname.php

namespace Vendor\Module\Block\Adminhtml\Renderer;

class Classname extends \Magento\Framework\Data\Form\Element\AbstractElement
{
    public function getElementHtml()
    {
        $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
        $product = $objectManager->create('Vendor\Module\Block\Adminhtml\Path to your grid file')->getBlockGrid(); //can inject also I used ObjectManager for testing

        $html = parent::getElementHtml();
        $value = $this->getValue();
        $html.=$product;
        return $html;
    }
}
?>

In your Grid file at Vendor/Module/Block/Adminhtml/Path to gridfile.php

<?php

namespace Vendor\Module\Block\Adminhtml;

class Grid extends \Magento\Backend\Block\Widget\Grid\Extended
{
    protected $productFactory;

    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Backend\Helper\Data $backendHelper,
        \Magento\Catalog\Model\ProductFactory $productFactory,
        \Magento\Framework\Registry $coreRegistry,
        array $data = []
    ) {
        $this->productFactory = $productFactory;
        $this->_coreRegistry = $coreRegistry;
        parent::__construct($context, $backendHelper, $data);
    }

    /**
     * @return void
     */
    protected function _construct()
    {
        // parent::_construct();
        // $this->setId('hello_tab_grid');
        // $this->setDefaultSort('entity_id');
        $this->setUseAjax(true);
    }

    /**
     * @return Grid
     */
    protected function _prepareCollection()
    {
        $collection = $this->productFactory->create()->getCollection()->addAttributeToSelect("*");
        $this->setCollection($collection);
        return parent::_prepareCollection();
    }

    /**
     * @return Extended
     */
    protected function _prepareColumns()
    {
        $this->addColumn(
            'entity_id',
            [
                'header' => __('Product Id'),
                'sortable' => true,
                'index' => 'entity_id',
                'header_css_class' => 'col-id',
                'column_css_class' => 'col-id'
            ]
        );
        $this->addColumn(
            'name',
            [
                'header' => __('Product Name'),
                'index' => 'name'
            ]
        );
        $this->addColumn(
            'sku',
            [
                'header' => __('Sku'),
                'index' => 'sku'
            ]
        );

        return parent::_prepareColumns();
    }

    /**
     * @return string
     */
    public function getGridUrl()
    {
        return $this->getUrl('moduler/*/action', ['_current' => true]);
    }
public function getBlockGrid()
    {
        if (null === $this->blockGrid) {
            $this->blockGrid = $this->getLayout()->createBlock(
                '\Vendor\Module\Block\Adminhtml\Path to your grid file',
                'category.product.grid'
            );
        }
        return $this->blockGrid->toHtml();
    }
    
}

Answer 2

In order to add custom grid in customer group edit form you need to override the controller and custom block to render grid in it.

Create custom module for it

Vendor/Module/etc.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Magento\Customer\Controller\Adminhtml\Group\NewAction" type="Vendor\Module\Rewrite\Magento\Customer\Controller\Adminhtml\Group\NewAction"/>
</config>

Vendor/Module/Rewrite/Magento/Customer/Controller/Adminhtml/Group/NewAction.php

<?php
/**
 * Copyright © Dev All rights reserved.
 * See COPYING.txt for license details.
 */
declare(strict_types=1);

namespace Vendor\Module\Rewrite\Magento\Customer\Controller\Adminhtml\Group;

class NewAction extends \Magento\Customer\Controller\Adminhtml\Group\NewAction
{
    /**
     * Edit or create customer group.
     *
     * @return \Magento\Backend\Model\View\Result\Page
     */
    public function execute()
    {
        $groupId = $this->_initGroup();

        /** @var \Magento\Backend\Model\View\Result\Page $resultPage */
        $resultPage = $this->resultPageFactory->create();
        $resultPage->setActiveMenu('Magento_Customer::customer_group');
        $resultPage->getConfig()->getTitle()->prepend(__('Customer Groups'));
        $resultPage->addBreadcrumb(__('Customers'), __('Customers'));
        $resultPage->addBreadcrumb(__('Customer Groups'), __('Customer Groups'), $this->getUrl('customer/group'));

        if ($groupId === null) {
            $resultPage->addBreadcrumb(__('New Group'), __('New Customer Groups'));
            $resultPage->getConfig()->getTitle()->prepend(__('New Customer Group'));
        } else {
            $resultPage->addBreadcrumb(__('Edit Group'), __('Edit Customer Groups'));
            $resultPage->getConfig()->getTitle()->prepend(
                $this->groupRepository->getById($groupId)->getCode()
            );
        }

        $resultPage->getLayout()->addBlock(\Magento\Customer\Block\Adminhtml\Group\Edit::class, 'group', 'content')
            ->setEditMode((bool)$groupId);


        $resultPage->getLayout()->addBlock(\Vendor\Module\Block\Adminhtml\Group\Grid::class, 'custom_grid', 'content')
            ->setEditMode((bool)$groupId);

        return $resultPage;
    }
}

Vendor/Module/Block/Adminhtml/Group/Grid.php

<?php

namespace Vendor\Module\Block\Adminhtml\Group;

class Grid extends \Magento\Backend\Block\Widget\Grid\Extended
{
    protected $productFactory;

    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Backend\Helper\Data $backendHelper,
        \Magento\Catalog\Model\ProductFactory $productFactory,
        \Magento\Framework\Registry $coreRegistry,
        array $data = []
    ) {
        $this->productFactory = $productFactory;
        $this->_coreRegistry = $coreRegistry;
        parent::__construct($context, $backendHelper, $data);
    }

    /**
     * @return void
     */
    protected function _construct()
    {
        // parent::_construct();
        // $this->setId('hello_tab_grid');
        // $this->setDefaultSort('entity_id');
        $this->setUseAjax(true);
    }

    /**
     * @return Grid
     */
    protected function _prepareCollection()
    {
        $collection = $this->productFactory->create()->getCollection()->addAttributeToSelect("*");
        $this->setCollection($collection);
        return parent::_prepareCollection();
    }

    /**
     * @return Extended
     */
    protected function _prepareColumns()
    {
        $this->addColumn(
            'entity_id',
            [
                'header' => __('Product Id'),
                'sortable' => true,
                'index' => 'entity_id',
                'header_css_class' => 'col-id',
                'column_css_class' => 'col-id'
            ]
        );
        $this->addColumn(
            'name',
            [
                'header' => __('Product Name'),
                'index' => 'name'
            ]
        );
        $this->addColumn(
            'sku',
            [
                'header' => __('Sku'),
                'index' => 'sku'
            ]
        );

        return parent::_prepareColumns();
    }

    /**
     * @return string
     */
    public function getGridUrl()
    {
        return $this->getUrl('hello/*/helloGrid', ['_current' => true]);
    }
    
}

This is just a overview to show custom grid, for full implementation and operations on custom grid please follow this Blog

Thanks!