Value.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Framework\App\Config;

/**
 * Config data model
 *
 * This model is temporarily marked as API since {@see \Magento\Framework\App\Config\ValueInterface} doesn't fit
 * developers' needs of extensibility. In 2.4 we are going to introduce a new interface which should cover all needs
 * and deprecate the mentioned together with the model
 *
 * @method string getScope()
 * @method \Magento\Framework\App\Config\ValueInterface setScope(string $value)
 * @method int getScopeId()
 * @method \Magento\Framework\App\Config\ValueInterface setScopeId(int $value)
 * @method string getPath()
 * @method \Magento\Framework\App\Config\ValueInterface setPath(string $value)
 * @method string getValue()
 * @method \Magento\Framework\App\Config\ValueInterface setValue(string $value)
 *
 * @api
 *
 * @SuppressWarnings(PHPMD.NumberOfChildren)
 * @since 100.0.2
 */
class Value extends \Magento\Framework\Model\AbstractModel implements \Magento\Framework\App\Config\ValueInterface
{
    /**
     * Prefix of model events names
     *
     * @var string
     */
    protected $_eventPrefix = 'config_data';

    /**
     * Parameter name in event
     *
     * In observe method you can use $observer->getEvent()->getObject() in this case
     *
     * @var string
     */
    protected $_eventObject = 'config_data';

    /**
     * @var \Magento\Framework\App\Config\ScopeConfigInterface
     */
    protected $_config;

    /**
     * @var \Magento\Framework\App\Cache\TypeListInterface
     */
    protected $cacheTypeList;

    /**
     * @param \Magento\Framework\Model\Context $context
     * @param \Magento\Framework\Registry $registry
     * @param ScopeConfigInterface $config
     * @param \Magento\Framework\App\Cache\TypeListInterface $cacheTypeList
     * @param \Magento\Framework\Model\ResourceModel\AbstractResource|null $resource
     * @param \Magento\Framework\Data\Collection\AbstractDb|null $resourceCollection
     * @param array $data
     */
    public function __construct(
        \Magento\Framework\Model\Context $context,
        \Magento\Framework\Registry $registry,
        \Magento\Framework\App\Config\ScopeConfigInterface $config,
        \Magento\Framework\App\Cache\TypeListInterface $cacheTypeList,
        \Magento\Framework\Model\ResourceModel\AbstractResource $resource = null,
        \Magento\Framework\Data\Collection\AbstractDb $resourceCollection = null,
        array $data = []
    ) {
        $this->_config = $config;
        $this->cacheTypeList = $cacheTypeList;
        parent::__construct($context, $registry, $resource, $resourceCollection, $data);
    }

    /**
     * Check if config data value was changed
     *
     * @return bool
     */
    public function isValueChanged()
    {
        return $this->getValue() != $this->getOldValue();
    }

    /**
     * Get old value from existing config
     *
     * @return string
     */
    public function getOldValue()
    {
        return (string)$this->_config->getValue(
            $this->getPath(),
            $this->getScope() ?: ScopeConfigInterface::SCOPE_TYPE_DEFAULT,
            $this->getScopeCode()
        );
    }

    /**
     * Get value by key for new user data from <section>/groups/<group>/fields/<field>
     *
     * @param string $key
     * @return string
     */
    public function getFieldsetDataValue($key)
    {
        $data = $this->_getData('fieldset_data');
        return is_array($data) && isset($data[$key]) ? $data[$key] : null;
    }

    /**
     * Processing object after save data
     *
     * {@inheritdoc}. In addition, it sets status 'invalidate' for config caches
     *
     * @return $this
     */
    public function afterSave()
    {
        if ($this->isValueChanged()) {
            $this->cacheTypeList->invalidate(\Magento\Framework\App\Cache\Type\Config::TYPE_IDENTIFIER);
        }

        return parent::afterSave();
    }

    /**
     * Processing object after delete data
     *
     * {@inheritdoc}. In addition, it sets status 'invalidate' for config caches
     *
     * @return $this
     * @since 100.1.0
     */
    public function afterDelete()
    {
        $this->cacheTypeList->invalidate(\Magento\Framework\App\Cache\Type\Config::TYPE_IDENTIFIER);

        return parent::afterDelete();
    }
}