Magento2 : How to show button in admin for custom module page?

Question

I want to show the button in my custom module (admin page)

but I am getting an error

I want to add a button and how I add action process for that button

i already tried this answer : (https://magento.stackexchange.com/a/212656/73525 )

GenericButton.php

    <?php
/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Webkul\Mpquotesystem\Block\Adminhtml\Managequotes\Edit;

use Magento\Backend\Block\Widget\Context;
//use FME\News\Api\NewsRepositoryInterface;
use Magento\Framework\Exception\NoSuchEntityException;

/**
 * Class GenericButton
 */
class GenericButton
{
    /**
     * @var Context
     */
    protected $context;

    /**
     * @var BlockRepositoryInterface
     */
    protected $blockRepository;

    /**
     * @param Context $context
     * @param BlockRepositoryInterface $blockRepository
     */
    public function __construct(
        Context $context
    ) {
        $this->context = $context;
        //$this->blockRepository = $blockRepository;
    }

    /**
     * Return CMS block ID
     *
     * @return int|null
     */
    public function getBlockId()
    {
/*
        {
            return $this->blockRepository->getById(
                $this->context->getRequest()->getParam('news_id')
            )->getId();
        }  */
        return null;
    }

    /**
     * Generate url by route and parameters
     *
     * @param   string $route
     * @param   array $params
     * @return  string
     */
    public function getUrl($route = '', $params = [])
    {
        return $this->context->getUrlBuilder()->getUrl($route, $params);
    }
}

SaveandContinuebutton.php

<?php

namespace  Webkul\Mpquotesystem\Block\Adminhtml\Managequotes\Edit;

use Magento\Framework\View\Element\UiComponent\Control\ButtonProviderInterface;

/**
 * Class SaveAndContinueButton
 */
class SaveAndContinueButton extends GenericButton implements ButtonProviderInterface
{

    public function getButtonData()
    {
        return [
            'label' => __('ADmin pproval'),
            'class' => 'save',
            'on_click' => 'location.reload();',
            'sort_order' => 30
        ];
    }
}

view/adminhtml/uicomponent/custommodule_edit.xml

<?xml version="1.0"?>
<!-- /**
 * Webkul Software
 *
 * @category  Webkul
 * @package   Webkul_Mpquotesystem
 * @author    Webkul
 * @copyright Copyright (c) 2010-2018 Webkul Software Private Limited (https://webkul.com)
 * @license   https://store.webkul.com/license.html
 */ -->
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <argument name="data" xsi:type="array">

    <item name="buttons" xsi:type="array">
        <item name="save_and_continue" xsi:type="string">Webkul\Mpquotesystem\Block\Adminhtml\Managequotes\Edit\SaveAndContinueButton</item>
    </item>

    </argument>
</form>

when clicking that admin custom module page :

Fatal error: Method Magento\Ui\TemplateEngine\Xhtml\Result::__toString() must not throw an exception, caught Error: Call to a member function getRequestFieldName() on null in /var/www/html/equpo2/vendor/magento/module-ui/Component/Wrapper/UiComponent.php on line

Answer 1

Just change your SaveAndContinueButton file: and chek after clearing generated folder

       namespace Webkul\Mpquotesystem\Block\Adminhtml\Managequotes\Edit;

        use Magento\Customer\Api\AccountManagementInterface;
        use Magento\Framework\View\Element\UiComponent\Control\ButtonProviderInterface;

        class SaveAndContinueButton  implements ButtonProviderInterface
        {

            public function getButtonData()
            {
                return [
                    'label' => __('Save and Continue Edit'),
                    'class' => 'save',
                    'data_attribute' => [
                        'mage-init' => ['button' => ['event' => 'saveAndContinueEdit']],
                        'form-role' => 'save',
                    ],
                    'sort_order' => 80,
                ];
            }

        }