Item (Magento\Wishlist\Model\Item) with the same ID X already exists

Question

I am having a strange problem with my Magento installation. As soon as I add a product to my wishlist (any customer), I am getting the following error in the browser's console:

Item (Magento\Wishlist\Model\Item) with the same ID X already exists.

Due to which the mini cart is not showing cart items count.

I tried to truncate the tables related to wishlist:

• wishlist
• wishlist_item
• wishlist_item_option
• email_wishlist

But every time an item is added to the wishlist, the error appears in the console.

One more (maybe related) error I noticed is in customer-data.js

Maybe this is also a relevant clue:

Update: I have tried to disable the custom modules which are overriding customer-data.js.

Thanks for your kind help in advance.

Answer 1

this message

'..with the same ID X already exists'

typically happens when a collection is created and a wishlist item model is assigned to the collection twice

--> the reason often is that the wishlist collection has been altered via a customisation from a third-party module. To troubleshoot, I would start directly in the collection class: \Magento\Wishlist\Model\ResourceModel\Wishlist\Collection

for instance, you can add a temporary function protected function _beforeLoad in this class and put some log that output the query:

$writer = new \Zend\Log\Writer\Stream(BP . '/var/log/wishlistquery.log');
$logger = new \Zend\Log\Logger();
$logger->addWriter($writer);
$logger->info($this->getSelect()->__toString()); 

then you can run the query in mysql and if the query returns duplicate id, that's a winner..

If this method does not work, you may have to track more closely the ajax call. I'd start then to look in the network panel and try to find a place where you can pinpoint what calls the wishlist collection.