How to check if cart is empty in observer Magento 2

Question

i created an observer before add to cart like this:

<?xml version="1.0"?>

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="controller_action_predispatch_checkout_cart_add">
        <observer name="test_custom_controller_action_predispatch_checkout_cart_add" instance="Test\Custom\Observer\BeforeAddCart" />
    </event>
</config>

in this observer i want to check if the cart is empty and do some function, before add product to the cart

Answer 1

You can also use the cart helper

 protected $cartHelper;

 public function __construct(     
        \Magento\Checkout\Helper\Cart $cartHelper
    ) {
        $this->cartHelper = $cartHelper;
    }

and then you can do the check

   if ($this->cartHelper->getItemsCount() === 0) {
          //add your functionality
   }

Answer 2

You can get item count using below way,

<?php
namespace Test\Custom\Observer;

use Magento\Framework\Event\ObserverInterface;

class BeforeAddCart implements ObserverInterface
{
    public function execute(\Magento\Framework\Event\Observer $observer)
    {        
        /** @var \Magento\Quote\Model\Quote\Item $item */
        $item = $observer->getEvent()->getQuoteItem();
        echo count($item);exit;
    }
}

Answer 3

protected $_cart;      

public function __construct(     
    \Magento\Checkout\Model\Cart $_cart
) {
    $this->_cart = $_cart;
}

Now you can use this like,

$quote=$this->_cart->getQuote();
$totalItems=count($quote->getAllItems());
if($totalItems==0){
    // do your stuff here
 }