Magento – Magento 2 : How to Override Block File

I need override block file in custom module. Below is block file path.

vendor/magento/module-sales/Block/Adminhtml/Order/Create/Search/Grid.php

How can I do that?

Yes, please check this error and code what i get.

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\Sales\Block\Adminhtml\Order\Create\Search\Grid" type="Company\ModuleName\Block\Adminhtml\Order\Create\Search\Grid" />
</config>

Bloc/Adminhtml/order/Create/Search/Grid.php

<?php

namespace Company\ModuleName\Block\Adminhtml\Order\Create\Search;


class Grid extends \Magento\Sales\Block\Adminhtml\Order\Create\Search\Grid
{
    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Backend\Helper\Data $backendHelper,
        \Magento\Catalog\Model\ProductFactory $productFactory,
        \Magento\Catalog\Model\Config $catalogConfig,
        \Magento\Backend\Model\Session\Quote $sessionQuote,
        \Magento\Sales\Model\Config $salesConfig,
        array $data = []
    ) {
        $this->_productFactory = $productFactory;
        $this->_catalogConfig = $catalogConfig;
        $this->_sessionQuote = $sessionQuote;
        $this->_salesConfig = $salesConfig;
        parent::__construct($context, $backendHelper, $data);
    }


    /**
     * Prepare collection to be displayed in the grid
     *
     * @return $this
     */
    protected function _prepareCollection()
    {
        $attributes = $this->_catalogConfig->getProductAttributes();
        /* @var $collection \Magento\Catalog\Model\ResourceModel\Product\Collection */
        $collection = $this->_productFactory->create()->getCollection();
        $collection->setStore(
            $this->getStore()
        )->addAttributeToSelect(
            $attributes
        )->addAttributeToSelect(
            'sku'
        )->addStoreFilter()->addAttributeToFilter(
            'type_id',
            $this->_salesConfig->getAvailableProductTypes()
        )->addAttributeToSelect(
            'gift_message_available'
        );

       $collection->joinField(
                'qty_in_stock',
                'cataloginventory_stock_item',
                'qty',
                'product_id=entity_id',
                '{{table}}.stock_id=1',
                'left'
        );

        $this->setCollection($collection);
        return parent::_prepareCollection();
    }

    /**
     * Prepare columns
     *
     * @return $this
     */
    protected function _prepareColumns()
    {
        $this->addColumn(
            'entity_id',
            [
                'header' => __('ID'),
                'sortable' => true,
                'header_css_class' => 'col-id',
                'column_css_class' => 'col-id',
                'index' => 'entity_id'
            ]
        );
        $this->addColumn(
            'name',
            [
                'header' => __('Product'),
                'renderer' => 'Magento\Sales\Block\Adminhtml\Order\Create\Search\Grid\Renderer\Product',
                'index' => 'name'
            ]
        );
        $this->addColumn('sku', ['header' => __('SKU'), 'index' => 'sku']);
        $this->addColumn(
            'price',
            [
                'header' => __('Price'),
                'column_css_class' => 'price',
                'type' => 'currency',
                'currency_code' => $this->getStore()->getCurrentCurrencyCode(),
                'rate' => $this->getStore()->getBaseCurrency()->getRate($this->getStore()->getCurrentCurrencyCode()),
                'index' => 'price',
                'renderer' => 'Magento\Sales\Block\Adminhtml\Order\Create\Search\Grid\Renderer\Price'
            ]
        );
       $this->addColumn(
                'qty_in_stock',
                [
                'header' => __('Quantity In Stock'),
                'type' => 'number',
                'index' => 'qty_in_stock'
                ]
        );
        $this->addColumn(
            'in_products',
            [
                'header' => __('Select'),
                'type' => 'checkbox',
                'name' => 'in_products',
                'values' => $this->_getSelectedProducts(),
                'index' => 'entity_id',
                'sortable' => false
            ]
        );

        $this->addColumn(
            'qty',
            [
                'filter' => false,
                'sortable' => false,
                'header' => __('Quantity'),
                'renderer' => 'Magento\Sales\Block\Adminhtml\Order\Create\Search\Grid\Renderer\Qty',
                'name' => 'qty',
                'inline_css' => 'qty',
                'type' => 'input',
                'validate_class' => 'validate-number',
                'index' => 'qty'
            ]
        );

        return parent::_prepareColumns();
    }

    /**
     * Get grid url
     *
     * @return string
     */
    public function getGridUrl()
    {
        return $this->getUrl(
            'sales/*/loadBlock',
            ['block' => 'search_grid', '_current' => true, 'collapse' => null]
        );
    }

    /**
     * Get selected products
     *
     * @return mixed
     */
    protected function _getSelectedProducts()
    {
        $products = $this->getRequest()->getPost('products', []);

        return $products;
    }

    /**
     * Add custom options to product collection
     *
     * @return $this
     */
    protected function _afterLoadCollection()
    {
        $this->getCollection()->addOptionsToResult();
        return parent::_afterLoadCollection();
    }


}

Just i need override this block and add new column for available qty for the product and it used when create order from admin. So please check let me know what i missing.