Override Flat Rate Model using Plugin

Question

I have to override method using plugin.

private function getShippingPrice(RateRequest $request, $freeBoxes)
{
    $shippingPrice = false;

    $configPrice = $this->getConfigData('price');
    if ($this->getConfigData('type') === 'O') {
        // per order
        $shippingPrice = $this->itemPriceCalculator->getShippingPricePerOrder($request, $configPrice, $freeBoxes);
    } elseif ($this->getConfigData('type') === 'I') {
        // per item
        $shippingPrice = $this->itemPriceCalculator->getShippingPricePerItem($request, $configPrice, $freeBoxes);
    }

    $shippingPrice = $this->getFinalPriceWithHandlingFee($shippingPrice);

    if ($shippingPrice !== false && $request->getPackageQty() == $freeBoxes) {
        $shippingPrice = '0.00';
    }
    return $shippingPrice;
}

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">
    <type name="Magento\OfflineShipping\Model\Carrier\Flatrate">
        <plugin name="vendor_module_offlineshipping_carrier_flatrate" type="Vendor\Module\Plugin\Flatrate" />
</type>
</config>

I have to do per vendor flate rate shipping as below

if ($this->getConfigData('type') === 'V') {
        // per item
        $shippingPrice = $this->itemPriceCalculator->getShippingPricePerVendor($request, $configPrice, $freeBoxes);
    }

Please help me to override above method.If anyone know reply me.

Answer 1

To override the functionality of flatrate using plugin for private method.

1st Step: we need to add in Vendor/Module/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">
   <type name="Magento\OfflineShipping\Model\Carrier\Flatrate">
        <plugin name="vendor_module_offlineshipping_carrier_flatrate" type="Vendor\Module\Plugin\Flatrate" />
   </type>
   <type name="Magento\OfflineShipping\Model\Config\Source\Flatrate">
       <plugin name="vendor_module_option_variable" type="Vendor\Module\Model\Config\Source\Flatrate"/>
   </type>
</config>

2nd step: we need to override the optionArray for flatrate using plugin to show vendor option in admin side

<?php
/**
* Copyright © Magento, Inc. All rights reserved.
* See COPYING.txt for license details.
*/
namespace Vendor\Module\Model\Config\Source;

/**
* @api
* @since 100.0.2
*/
class Flatrate
{
   /**
    * {@inheritdoc}
    */
   public function afterToOptionArray(\Magento\OfflineShipping\Model\Config\Source\Flatrate $subject,
       $result)
   {
       $result= [
           ['value' => '', 'label' => __('None')],
           ['value' => 'O', 'label' => __('Per Order')],
           ['value' => 'I', 'label' => __('Per Item')],
           ['value' => 'V', 'label' => __('Per Vendor')]
       ];

       return $result;
   }
}

3rd step: You will see the option in admin panel under

stores => settings => configuration => sales => shipping methods => flatrate

4th step: main file to override the shipping price

Vendor/Module/Plugin/Flatrate.php

<?php

namespace Vendor\Module\Plugin;

use Magento\OfflineShipping\Model\Carrier\Flatrate as Subject;
use Magento\Quote\Model\Quote\Address\RateRequest;
use Magento\Shipping\Model\Rate\Result;

class Flatrate
{  
    /**
    * @var string
    */
   protected $_code = 'flatrate';

   /**
    * @var bool
    */
   protected $_isFixed = true;

   /**
    * @var \Magento\Shipping\Model\Rate\ResultFactory
    */
   protected $_rateResultFactory;

   /**
    * @var \Magento\Quote\Model\Quote\Address\RateResult\MethodFactory
    */
   protected $_rateMethodFactory;
    /**
    * @var ItemPriceCalculator
    */
   private $itemPriceCalculator;

   public function __construct(
       \Magento\Quote\Model\Quote\Address\RateResult\ErrorFactory $rateErrorFactory,
       \Magento\Shipping\Model\Rate\ResultFactory $rateResultFactory,
       \Magento\Quote\Model\Quote\Address\RateResult\MethodFactory $rateMethodFactory,
       \Magento\OfflineShipping\Model\Carrier\Flatrate\ItemPriceCalculator $itemPriceCalculator
   ) {
       $this->_rateResultFactory = $rateResultFactory;
       $this->_rateMethodFactory = $rateMethodFactory;
       $this->_rateErrorFactory=$rateErrorFactory;
       $this->itemPriceCalculator=$itemPriceCalculator;
   }

   public function aroundCollectRates(Subject $subject,\Closure $proceed,RateRequest $request)
   {


      if (!$subject->getConfigFlag('active')) {
           return false;
       }
       $freeBoxes = $subject->getFreeBoxesCount($request);
       $subject->setFreeBoxes($freeBoxes);

      if (!subject->getConfigFlag('active')) {
           return false;
       }

       $freeBoxes = $subject->getFreeBoxesCount($request);
       $subject->setFreeBoxes($freeBoxes);

       /** @var Result $result */
       $result = $this->_rateResultFactory->create();

       $shippingPrice = $this->getShippingPrice($subject,$request, $freeBoxes);

       if ($shippingPrice !== false) {
           $method = $this->createResultMethod($shippingPrice,$subject,$request);
           $result->append($method);
       }

       return $result;

   }


   private function createResultMethod($shippingPrice,$subject,$request)
   {
       /** @var \Magento\Quote\Model\Quote\Address\RateResult\Method $method */
       $method = $this->_rateMethodFactory->create();

       $method->setCarrier('flatrate');
       $method->setCarrierTitle($subject->getConfigData('title'));

       $method->setMethod('flatrate');
       $method->setMethodTitle($subject->getConfigData('name'));

       $method->setPrice($shippingPrice);
       $method->setCost($shippingPrice);
       return $method;
   } 

   private function getShippingPrice($subject,$request, $freeBoxes)
   {
       $shippingPrice = false;

       $configPrice = $subject->getConfigData('price');
       if ($subject->getConfigData('type') === 'O') {
           // per order
           $shippingPrice = $this->itemPriceCalculator->getShippingPricePerOrder($request, $configPrice, $freeBoxes);
       } elseif ($subject->getConfigData('type') === 'I') {
           // per item
           $shippingPrice = $this->itemPriceCalculator->getShippingPricePerItem($request, $configPrice, $freeBoxes);
         // per vendor
       }else if ($this->getConfigData('type') === 'V') {

        $shippingPrice = $this->itemPriceCalculator->getShippingPricePerVendor($request, $configPrice, $freeBoxes);
    }

       $shippingPrice = $subject->getFinalPriceWithHandlingFee($shippingPrice);

       if ($shippingPrice !== false && $request->getPackageQty() == $freeBoxes) {
           $shippingPrice = '0.00';
       }
       return $shippingPrice;
   }

}