Magento 2 : Exception #0 (InvalidArgumentException): Invalid return type

Question

Exception

 Exception #0 (InvalidArgumentException): Invalid return type
    #0 /var/www/html/magento/folder/vendor/magento/framework/App/Bootstrap.php(258): Magento\Framework\App\Http->launch()
    #1 /var/www/html/magento/folder/index.php(39): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http\Interceptor))
    #2 {main}

Controller

 protected $wishlist;


    public function __construct(
        \Magento\Wishlist\Model\Wishlist $wishlist,
        \Magento\Framework\App\Request\Http $request,
        \Magento\Customer\Model\Session $customerSession,
        \Magento\Framework\App\Action\Context $context,
        \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory
    ) {
        $this->wishlist = $wishlist;
        $this->request = $request;
        $this->customerSession = $customerSession;
        $this->resultJsonFactory = $resultJsonFactory;
        parent::__construct($context);
    }

      public function execute()
{
    $productId = $this->request->getPostValue('productId');
    $resultJson = $this->resultJsonFactory->create();
    $resultJson->setData(['productId' => $productId]);
    $customerId = $this->customerSession->getCustomer()->getId();

    $wish = $this->wishlist->loadByCustomerId($customerId);
    $items = $wish->getItemCollection();

    /** @var \Magento\Wishlist\Model\Item $item */
    foreach ($items as $item) {
        if ($item->getProductId() == $productId) {
            $item->delete();
            $wish->save();
        }
    }
}
}

Ajax

  var pdtId = $(this).attr('data-pdtId');
                $.ajax({
                    type: "POST",
                    url: customRemoveurl,
                    data: {
                        productId: pdtId,
                    },
                    success: function(response) {
                        console.log(response);
                    },
                    error: function(error) {
                        // console.log(error);
                    }
                });

Answer 1

Pass data with json format and replace your success ajax console :

Controller :

protected $wishlist;


public function __construct(
    \Magento\Wishlist\Model\Wishlist $wishlist,
    \Magento\Framework\App\Request\Http $request,
    \Magento\Customer\Model\Session $customerSession,
    \Magento\Framework\App\Action\Context $context,
    \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory
) {
    $this->wishlist = $wishlist;
    $this->request = $request;
    $this->customerSession = $customerSession;
    $this->resultJsonFactory = $resultJsonFactory;
    parent::__construct($context);
}

public function execute()
{
    $productId = $this->request->getPostValue('productId');
    $resultJson = $this->resultJsonFactory->create();
    return $resultJson->setData(['productId' => $productId]);
}

Ajax :

var pdtId = $(this).attr('data-pdtId');
$.ajax({
    type: "POST",
    url: customRemoveurl,
    data: {
        productId: pdtId,
    },
    success: function(response) {
        console.log(response.productId);
    },
    error: function(error) {
        // console.log(error);
    }
});

Answer 2

Do it like this

protected $wishlist;


public function __construct(
    \Magento\Wishlist\Model\Wishlist $wishlist,
    \Magento\Framework\App\Request\Http $request,
    \Magento\Customer\Model\Session $customerSession,
    \Magento\Framework\App\Action\Context $context,
    \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory
) {
    $this->wishlist = $wishlist;
    $this->request = $request;
    $this->customerSession = $customerSession;
    $this->resultJsonFactory = $resultJsonFactory;
    parent::__construct($context);
}

public function execute()
{
  $resultRedirect = $this->resultRedirectFactory->create();
  $productId = $this->request->getPostValue('productId');

        return $productId;
 }