Magento : Add product to wish list programatically - magento

Question

I have added the below code in my controller to add the product to wishlist programmatically. But whenever ajax request goes to the controller it replaces my previously added product from the wishlist and adds the new one to wishlist.
Can somebody please help with this.
if (Mage::getSingleton('customer/session')->isLoggedIn()) {
// Load the customer's data
$customer = Mage::getSingleton('customer/session')->getCustomer();
//echo $customer->getName(); // Full Name
$customerId = $customer->getId(); // First Name
$wishlist = Mage::getModel('wishlist/wishlist')->loadByCustomer($customerId, true);
$product = Mage::getModel('catalog/product')->load($productId);
$result = $wishlist->addNewItem($product);
$wishlist->save();
echo "added to wishlist";
}

Answer 1

You can try below :
$product = Mage::getModel('catalog/product')->load($productId);
if (!$product->getId() || !$product->isVisibleInCatalog()) {
//$this->__('Cannot specify product.');
}
try {
$requestParams = $this->getRequest()->getParams();
$buyRequest = new Varien_Object($requestParams=array());
$result = $wishlist->addNewItem($product, $buyRequest);
if (is_string($result)) {
Mage::throwException($result);
}
$wishlist->save();
Mage::dispatchEvent(
'wishlist_add_product',
array(
'wishlist' => $wishlist,
'product' => $product,
'item' => $result
)
);
Mage::helper('wishlist')->calculate();
$message = $this->__('%1$s has been added to your wishlist. Click here to continue shopping.',
$product->getName(), Mage::helper('core')->escapeUrl($referer));
} catch (Mage_Core_Exception $e) {
echo $this->__('An error occurred while adding item to wishlist: %s', $e->getMessage());
}
catch (Exception $e) {
echo ($this->__('An error occurred while adding item to wishlist.'));
}