How to create backorder programatically magento 2?

Question

I am using the following code to add products to Quote object which throws an error if the product is out of stock.

/** @var \Magento\Catalog\Model\Product $product */
$product->setTaxClassId($this->getTaxClassId())
        ->setPrice($price)
        ->setSpecialPrice($price)
        ->setTierPrice([])
        ->setBasePrice($baseprice)
        ->setOriginalCustomPrice($price)
        ->setRowTotal($rowTotal)
        ->setBaseRowTotal($rowTotal);
/** @var \Magento\Quote\Model\Quote $quote */
$quote->addProduct($product, (int)$qty);

How do I override the product qty check and create a backorder for each case ?

Answer 1

My other question solved the problem. What does “setIsSuperMode” do on Quote Object in Magento 2?

/** @var \Magento\Catalog\Model\Product $product */
$product->setTaxClassId($this->getTaxClassId())
        ->setPrice($price)
        ->setSpecialPrice($price)
        ->setTierPrice([])
        ->setBasePrice($baseprice)
        ->setOriginalCustomPrice($price)
        ->setRowTotal($rowTotal)
        ->setBaseRowTotal($rowTotal);

/** @var \Magento\Quote\Model\Quote $quote */
$quote->setIsSuperMode(true);
$quote->addProduct($product, (int)$qty);

Essentially it is a flag on the quote that this quote has been created by an admin. The effect of this is in the locations you stated that an admin can, for example, create an order for an item that normally would be out of stock or is not visible in the catalog.

Answer 2

you can get the product stock and put the condition on that, here is a code for getting product stock.

<?php
namespace vendor\module\Block;
class ProductStock extends \Magento\Framework\View\Element\Template
{    
    protected $_stockItemRepository;

    public function __construct(
        \Magento\Backend\Block\Template\Context $context,        
        \Magento\CatalogInventory\Model\Stock\StockItemRepository $stockItemRepository,
        array $data = []
    )
    {
        $this->_stockItemRepository = $stockItemRepository;
        parent::__construct($context, $data);
    }

    public function getStockItem($productId)
    {
        return $this->_stockItemRepository->get($productId);
    }
}
?>

<?php
    $id = 123;
    $_productStock = $block->getStockItem($id);
    //print_r($_productStock->getData()); 
    echo $_productStock->getQty(); echo '<br />';
    echo $_productStock->getMinQty(); echo '<br />';
    echo $_productStock->getMinSaleQty(); echo '<br />';
    echo $_productStock->getMaxSaleQty(); echo '<br />';
    echo $_productStock->getIsInStock(); echo '<br />';
?>