Magento 2.4 Preference on Block does not work

Question

What i'm trying to do is to rewrite a core function of ( MagentoMagento\ConfigurableProduct\Block\Product\View\Type\Configurable )

The function is called getJsonConfig()

 public function getJsonConfig()
{
    $store = $this->getCurrentStore();
    $currentProduct = $this->getProduct();
    // original Code
    //  $options = $this->helper->getOptions($currentProduct, $this->getAllowProducts());
   
    // New code 
    $options = $this->helper->getOptions($currentProduct, $this->getProduct()->getTypeInstance()->getUsedProducts($this->getProduct(), null) ); 
    $attributesData = $this->configurableAttributeData->getAttributesData($currentProduct, $options);

    $config = [
        'attributes' => $attributesData['attributes'],
        'template' => str_replace('%s', '<%- data.price %>', $store->getCurrentCurrency()->getOutputFormat()),
        'currencyFormat' => $store->getCurrentCurrency()->getOutputFormat(),
        'optionPrices' => $this->getOptionPrices(),
        'priceFormat' => $this->localeFormat->getPriceFormat(),
        'prices' => $this->variationPrices->getFormattedPrices($this->getProduct()->getPriceInfo()),
        'productId' => $currentProduct->getId(),
        'chooseText' => __('Choose an Option...'),
        'images' => $this->getOptionImages(),
        'index' => isset($options['index']) ? $options['index'] : [],
    ];


    if ($currentProduct->hasPreconfiguredValues() && !empty($attributesData['defaultValues'])) {
        $config['defaultValues'] = $attributesData['defaultValues'];
    }

    $config = array_merge($config, $this->_getAdditionalConfig());

    return $this->jsonEncoder->encode($config);
}

So i did some research how i could do this and what i found was that using a preference is the best way to do this because i have to rewrite a pice of the core code.

I have create a module with the di.xlm in the etc/frontend folder and also extend the Block with the original class but that did not work

I my module.xml i also added a sequence but that also did not work.

I have done setup:upgrade/di:compile /cache:clean /removed generated also var

bit i still does not work. I was first looking in to using a plugin or events & observers but those can't rewrite the core code. So now i don't know what to try else i will post my code below.

Registraion.php

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Maerschalk_ConfigurableProductAttributes',
    __DIR__
);

Module.xml

    <?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Maerschalk_ConfigurableProductAttributes" setup_version="1.0.0">
    <sequence>
    <module name="Magento_ConfigurableProduct" />
    </sequence>
    </module>

</config>

di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
<preference for="Magento\ConfigurableProduct\Block\Product\View\Type\Configurable" type="Maerschalk\ConfigurableProductAttributes\Block\Product\View\Type\Configurable" />

Configurable

    <?php 

namespace Maerschalk\ConfigurableProductAttributes\Block\Product\View\Type;

class Configurable extends \Magento\ConfigurableProduct\Block\Product\View\Type\Configurable
{
    /**
     * Composes configuration for js
     *
     * @return string
     */
    public function getJsonConfig()
    {
        $store = $this->getCurrentStore();
        $currentProduct = $this->getProduct();
  
        //  $options = $this->helper->getOptions($currentProduct, $this->getAllowProducts());
        $options = $this->helper->getOptions($currentProduct, $this->getProduct()->getTypeInstance()->getUsedProducts($this->getProduct(), null) ); 
        $attributesData = $this->configurableAttributeData->getAttributesData($currentProduct, $options);

        $config = [
            'attributes' => $attributesData['attributes'],
            'template' => str_replace('%s', '<%- data.price %>', $store->getCurrentCurrency()->getOutputFormat()),
            'currencyFormat' => $store->getCurrentCurrency()->getOutputFormat(),
            'optionPrices' => $this->getOptionPrices(),
            'priceFormat' => $this->localeFormat->getPriceFormat(),
            'prices' => $this->variationPrices->getFormattedPrices($this->getProduct()->getPriceInfo()),
            'productId' => $currentProduct->getId(),
            'chooseText' => __('Choose an Option...'),
            'images' => $this->getOptionImages(),
            'index' => isset($options['index']) ? $options['index'] : [],
        ];


        if ($currentProduct->hasPreconfiguredValues() && !empty($attributesData['defaultValues'])) {
            $config['defaultValues'] = $attributesData['defaultValues'];
        }

        $config = array_merge($config, $this->_getAdditionalConfig());

        return $this->jsonEncoder->encode($config);
    }
    
}

Answer 1

Try to put di.xml into etc and not etc/frontend.

Anyway, depending on what you are trying to do, almost everything can be achieved by a plugin. This is a public function, so with after, before or even around plugin you can hook into it.

And by the way, your di.xml does not have a closing tag, but I guess this is a copy&paste error?!