Ttdfjt

I am adding custom discount to my cart but it seems it is adding 2 times in the cart.

Here is my model file code.

$discount = 10;
$baseDiscount = 10;

$total->addTotalAmount('plandiscount', -$discount);
$total->addBaseTotalAmount('plandiscount', -$baseDiscount);
$total->setPlanDiscount(-$discount);
$total->setBasePlanDiscount(-$baseDiscount);
$quote->setGrandTotal($total->getGrandTotal() - $discount);
$quote->setBaseGrandTotal($total->getBaseGrandTotal() - $baseDiscount);

$quote->setPlanDiscount(-$discount);
$quote->setBasePlanDiscount(-$baseDiscount);

It is really strange that if the value is positive, it is working fine but in case of negative, it is adding 2 times.

Please try this way to apply custom discount

<?php
 namespace VendorMymoduleModelQuote;
 class Discount extends MagentoQuoteModelQuoteAddressTotalAbstractTotal
 
 public function __construct(
 MagentoFrameworkEventManagerInterface $eventManager,
 MagentoStoreModelStoreManagerInterface $storeManager,
 MagentoSalesRuleModelValidator $validator,
 MagentoFrameworkPricingPriceCurrencyInterface $priceCurrency
 ) 
 
 $this->setCode('testdiscount');
 $this->eventManager = $eventManager;
 $this->calculator = $validator;
 $this->storeManager = $storeManager;
 $this->priceCurrency = $priceCurrency;
 

 public function collect(
 MagentoQuoteModelQuote $quote,
 MagentoQuoteApiDataShippingAssignmentInterface $shippingAssignment,
 MagentoQuoteModelQuoteAddressTotal $total
 )
 
 parent::collect($quote, $shippingAssignment, $total);
 $address = $shippingAssignment->getShipping()->getAddress();
 $label = 'My Custom Discount';
 $TotalAmount=$total->getSubtotal();
 $TotalAmount=$TotalAmount/10; //Set 10% discount

 $discountAmount ="-".$TotalAmount; 
 $appliedCartDiscount = 0;

 if($total->getDiscountDescription())
 
 $appliedCartDiscount = $total->getDiscountAmount();
 $discountAmount = $total->getDiscountAmount()+$discountAmount;
 $label = $total->getDiscountDescription().', '.$label;
 

 $total->setDiscountDescription($label);
 $total->setDiscountAmount($discountAmount);
 $total->setBaseDiscountAmount($discountAmount);
 $total->setSubtotalWithDiscount($total->getSubtotal() + $discountAmount);
 $total->setBaseSubtotalWithDiscount($total->getBaseSubtotal() + $discountAmount);

 if(isset($appliedCartDiscount))
 
 $total->addTotalAmount($this->getCode(), $discountAmount - $appliedCartDiscount);
 $total->addBaseTotalAmount($this->getCode(), $discountAmount - $appliedCartDiscount);
 
 else 
 
 $total->addTotalAmount($this->getCode(), $discountAmount);
 $total->addBaseTotalAmount($this->getCode(), $discountAmount);
 
 return $this;
 

 public function fetch(MagentoQuoteModelQuote $quote, MagentoQuoteModelQuoteAddressTotal $total)
 
 $result = null;
 $amount = $total->getDiscountAmount();

 if ($amount != 0)
 
 $description = $total->getDiscountDescription();
 $result = [
 'code' => $this->getCode(),
 'title' => strlen($description) ? __('Discount (%1)', $description) : __('Discount'),
 'value' => $amount
 ];
 
 return $result;