Magento 2: Free shipping should not work after applying discount coupon and total less than $50?

Question

I want to apply free shipping for subtotal more than $50 and it's working fine. but if customer applied any discount coupon then free shipping should not apply because grand total is less than $50. For now, Free shipping still applying because Subtotal is still greater than $50.

Can anyone help me how to remove free shipping if Grand total less than $50 after applying discount coupon?

Here is my code:

public function collectRates(RateRequest $request)
    {
        if (!$this->getConfigFlag('active')) {
            return false;
        }

        // exclude Virtual products price from Package value if pre-configured
        if (!$this->getConfigFlag('include_virtual_price') && $request->getAllItems()) {
            foreach ($request->getAllItems() as $item) {
                if ($item->getParentItem()) {
                    continue;
                }
                if ($item->getHasChildren() && $item->isShipSeparately()) {
                    foreach ($item->getChildren() as $child) {
                        if ($child->getProduct()->isVirtual()) {
                            $request->setPackageValue($request->getPackageValue() - $child->getBaseRowTotal());
                        }
                    }
                } elseif ($item->getProduct()->isVirtual()) {
                    $request->setPackageValue($request->getPackageValue() - $item->getBaseRowTotal());
                }
            }
        }

        // Free shipping by qty
        $freeQty = 0;
        if ($request->getAllItems()) {
            $freePackageValue = 0;
            foreach ($request->getAllItems() as $item) {
                if ($item->getProduct()->isVirtual() || $item->getParentItem()) {
                    continue;
                }

                if ($item->getHasChildren() && $item->isShipSeparately()) {
                    foreach ($item->getChildren() as $child) {
                        if ($child->getFreeShipping() && !$child->getProduct()->isVirtual()) {
                            $freeShipping = is_numeric($child->getFreeShipping()) ? $child->getFreeShipping() : 0;
                            $freeQty += $item->getQty() * ($child->getQty() - $freeShipping);
                        }
                    }
                } elseif ($item->getFreeShipping()) {
                    $freeShipping = is_numeric($item->getFreeShipping()) ? $item->getFreeShipping() : 0;
                    $freeQty += $item->getQty() - $freeShipping;
                    $freePackageValue += $item->getBaseRowTotal();
                }
            }
            $oldValue = $request->getPackageValue();
            $request->setPackageValue($oldValue - $freePackageValue);
        }

        if (!$request->getConditionMRName()) {
            $conditionName = $this->getConfigData('condition_name');
            $request->setConditionMRName($conditionName ? $conditionName : $this->defaultConditionName);
        }

        // Package weight and qty free shipping
        $oldWeight = $request->getPackageWeight();
        $oldQty = $request->getPackageQty();

        $request->setPackageWeight($request->getFreeMethodWeight());
        $request->setPackageQty($oldQty - $freeQty);

        /** @var \Magento\Shipping\Model\Rate\Result $result */
        $result = $this->rateResultFactory->create();
        $zipRange = $this->getConfigData('zip_range');
        $rateArray = $this->getRate($request, $zipRange);

        $request->setPackageWeight($oldWeight);
        $request->setPackageQty($oldQty);

        $foundRates = false;

        foreach ($rateArray as $rate) {
            if (!empty($rate) && $rate['price'] >= 0) {
                /** @var \Magento\Quote\Model\Quote\Address\RateResult\Method $method */
                $method = $this->resultMethodFactory->create();

                $method->setCarrier('matrixrate');
                $method->setCarrierTitle($this->getConfigData('title'));

                $method->setMethod('matrixrate_' . $rate['pk']);
                $method->setMethodTitle(__($rate['shipping_method']));

                if ($request->getFreeShipping() === true || $request->getPackageQty() == $freeQty) {
                    $shippingPrice = 0;
                } else {
                    $shippingPrice = $this->getFinalPriceWithHandlingFee($rate['price']);
                }

                $method->setPrice($shippingPrice);
                $method->setCost($rate['cost']);

                $result->append($method);
                $foundRates = true; // have found some valid rates
            }
        }

        if (!$foundRates) {
            /** @var \Magento\Quote\Model\Quote\Address\RateResult\Error $error */
            $error = $this->_rateErrorFactory->create(
                [
                    'data' => [
                        'carrier' => $this->_code,
                        'carrier_title' => $this->getConfigData('title'),
                        'error_message' => $this->getConfigData('specificerrmsg'),
                    ],
                ]
            );
            $result->append($error);
        }

        return $result;
    }

    /**
     * @param \Magento\Quote\Model\Quote\Address\RateRequest $request
     * @param bool $zipRange
     * @return array|bool
     */
    public function getRate(\Magento\Quote\Model\Quote\Address\RateRequest $request, $zipRange)
    {
        return $this->matrixrateFactory->create()->getRate($request, $zipRange);
    }

    /**
     * @param string $type
     * @param string $code
     * @return array
     * @throws \Magento\Framework\Exception\LocalizedException
     */
    public function getCode($type, $code = '')
    {
        $codes = [
            'condition_name' => [
                'package_weight' => __('Weight vs. Destination'),
                'package_value' => __('Order Subtotal vs. Destination'),
                'package_qty' => __('# of Items vs. Destination'),
            ],
            'condition_name_short' => [
                'package_weight' => __('Weight'),
                'package_value' => __('Order Subtotal'),
                'package_qty' => __('# of Items'),
            ],
        ];

        if (!isset($codes[$type])) {
            throw new LocalizedException(__('Please correct Matrix Rate code type: %1.', $type));
        }

        if ('' === $code) {
            return $codes[$type];
        }

        if (!isset($codes[$type][$code])) {
            throw new LocalizedException(__('Please correct Matrix Rate code for type %1: %2.', $type, $code));
        }

        return $codes[$type][$code];
    }

    /**
     * Get allowed shipping methods
     *
     * @return array
     */
    public function getAllowedMethods()
    {
        return ['matrixrate' => $this->getConfigData('name')];
    } ```

Answer 1

You can create a shopping cart rule to provide Free shipping

Under Actions tab,

1. Set Free Shipping to "For matching items only"
2. Set Apply to "Percent of product price discount"
3. Set Apply to Shipping Amount to "Yes"
4. Set Discount Amount to 0

Under Conditions tab, add condition "Subtotal greater than $50"

Set priority for this rule the lowest

For other discount rules, you can set the priority higher than that of free shipping rule

The Priority setting is important when two cart rules/coupon codes are valid for the same product at the same time. The rule with the highest Priority setting (0 being the highest) will get executed first.

If for any cart rule, Discard Subsequent Price Rules is set to "Yes", then other cart rules with lower priority will not be executed.

So in this case you can set priority for discount cart rule as 1 and shipping cart rule as 2.

Or if you to add subtotal with discount in cart rule condition you can try below

https://aureatelabs.com/magento-2/add-grand-total-in-the-shopping-cart-rule-condition/