Quote Item level manual Discount - Magento 2

Question

I need to give Quote Item level manual Discount for selected cart items. After giving discount Cart Item row total will change. As can't modify the product price so custom price solution is also not working.

I tried with a new discount total but it gives a discount on the whole cart.

Anyone, please suggest the best approach for giving a discount on Cart item level without modifying product price.

Answer 1

You can create a plugin for Magento\SalesRule\Model\Validator::process -

    class Myplugin
       {

        protected $discountFactory;

        public function __construct(\Magento\SalesRule\Model\Rule\Action\Discount\DataFactory $discountFactory){
        $this->discountFactory = $discountFactory;
    }

    public function aroundProcess(
        \Magento\SalesRule\Model\Validator $subject,
        \Closure $proceed,
        $item,
        \Magento\SalesRule\Model\Validator $validator
    ){
        $returnValue = $proceed($item);

        $discountData = $this->discountFactory->create();

        $discountData->setAmount('[my_discount_amount]');
        $discountData->setBaseAmount('[my_discount_amount]');
        $discountData->setOriginalAmount('[my_discount_amount]');
        $discountData->setBaseOriginalAmount('[my_discount_amount]');

        $this->setDiscountData($discountData, $item);

        return $returnValue;
    }
}

Replace the [my_discount_amount] with your discount amount.