Magento 2 - setCustomPrice() does not work after Quote Item Update

Question

I've been struggling with this issue for the past few weeks now.

My goal is to set a custom price for an item after I edit them on Cart.

Basically, I'm using an observer on the event checkout_cart_update_item_complete, and on that observer I eventually do the following:

$item->setCustomPrice($price);
$item->setOriginalCustomPrice($price);
$item->getProduct()->setIsSuperMode(true);
$item->save();

Where $item is the new quote item after the update (check Magento\Checkout\Controller\Cart\UpdateItemOptions.php) and $price is my custom price.

After this, the quote item price gets the value of 0, even though the custom_price field on database is actually the value that I wanted.

Any help is appreciated :)

Answer 1

Try to write your custom code under process() function.

vendor\magento\module-sales-rule\Model\Validator.php

/**
     * Quote item discount calculation process
     *
     * @param AbstractItem $item
     * @return $this
     */
    public function process(AbstractItem $item)
    {
     ..............
     ..............
     $price = 50;
     $item->setCustomPrice($price);
     $item->setOriginalCustomPrice($price);
     $item->getProduct()->setIsSuperMode(true);
     ..............
     ..............

    }

NOTE: Don't use $item->save() once and try.

I hope it help..!!

Answer 2

You should override Magento\Catalog\Model\Product\Type\Price

etc/di.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\Catalog\Model\Product\Type\Price" type="SY\Modulename\Model\Catalog\Product\Type\Price" />
</config>

and redefine getBasePrice

<?php 
namespace SY\Modulename\Model\Catalog\Product\Type;
class Price extends \Magento\Catalog\Model\Product\Type\Price {
    public function getBasePrice($product, $qty = null) {
        $price = (float) $product->getPrice();
        return min(
            $this->_applyTierPrice($product, $qty, $price),
            $this->_applySpecialPrice($product, $price),
            1.11 // where is your custom product price
        );
    }
}

for some reasons magento can ignore override for Magento\Catalog\Model\Product\Type\Price and then you should override Magento\Catalog\Model\Product\Type\FrontSpecialPrice

Also you can do this via observer

events.xml

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="catalog_product_get_final_price">
        <observer name="custom_price" instance="SY\Modulename\Observer\CatalogProductGetFinalPrice"/>
    </event>
</config>

and

<?php 
namespace SY\Modulename\Observer;
class CatalogProductGetFinalPrice implements \Magento\Framework\Event\ObserverInterface {
    public function execute(\Magento\Framework\Event\Observer $observer){
        $_product->setFinalPrice(your custom price);
        return $this;
    }
}