$_item->getChildren() returns empty array for parent cart items when cart is paginated

[samcleathero]

Preconditions (*)

1. PHP 7.4
2. Magento 2.4.3-p1 (also replicated in 2.3.5-p1 and 2.4.2)

Steps to reproduce (*)

1. Override cart item renderer template (Magento_Checkout/cart/item/default.phtml).
2. Add $_item->getChildren() to get child items of configurable products - I am using this to get stock levels for child products when a configurable product is added to the cart. For demo purposes, I have var_dumped $_item->getHasChildren() in the screenshots below.
3. Add enough individual products to the cart to trigger pagination in the cart (by default more than 20 products).
4. Observe that without pagination active, $_item->getHasChildren() returns NULL for simple products, and (bool)true for configurable products. When pagination is triggered, $item->getHasChildren() returns NULL for all products, including configurables with children.

Expected result (*)

var_dump($_item->getHasChildren()) should return (bool)true for configurable products. $_item->getChildren() should also return an Magento\Quote\Model\Quote\Item\AbstractItem array. This screenshot shows it working correctly for a cart where pagination has not been triggered.

Actual result (*)

var_dump($_item->getHasChildren()) actually returns NULL for configurable products. $_item->getChildren() also returns an empty array. This screenshot is taken once enough products have been added to the cart to trigger pagination.

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Please provide Severity assessment for the Issue as Reporter. This information will help during Confirmation and Issue triage processes.

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

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[samcleathero]

@magento give me 2.4-develop instance with extensions samcleathero/m2-item-render-test

Edit: this doesn't seem to have worked as I thought it would - hopefully somebody can take a look and figure out what I was trying to achieve!

[magento-deployment-service]

Hi @samcleathero. Thank you for your request. I'm working on Magento instance for you.

[magento-deployment-service]

Hi @samcleathero, here is your Magento Instance: https://b26a589b00d5c9d782886b45dab65007-2-4-develop.instances.magento-community.engineering
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[m2-assistant]

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[pikulsky]

The bug is in vendor/magento/module-checkout/Block/Cart/Grid.php.
See \Magento\Checkout\Block\Cart\Grid::getItems(), let's say the quote includes only configurable products:

1. if no pagination: parent::getItems() returns $this->getQuote()->getAllVisibleItems(), where

• first, all quote items are loaded: configurable (parent_item_id is null) and child simples (parent_item_id is not null)
• note, in \Magento\Quote\Model\ResourceModel\Quote\Item\Collection::_afterLoad() child quote items are assigned to the parent quote items
• then in getAllVisibleItems() all children are not included in the result array, but child quote items are still linked to the parents - items in the result.

2. if there is a pagination:

• getItemsForGrid() is used, and it builds a query originally without children:
  $itemCollection->addFieldToFilter('parent_item_id', ['null' => true]);
• This condition is important here since the correct page should be retrieved
• Since the current page is loaded by SQL means (OFFSET, LIMIT), that's why non-visible quote items should be skipped in SQL query (see \Magento\Checkout\Block\Cart\Grid::_prepareLayout(), $pager in setCollection() sets current page number and page size)
• Then the children are not linked to their parents afterwards, and as result - there is a bug.

As a possible solution I would suggest to add a custom quote items collection for pagination case.
It will be returned in getItemsForGrid().
That collection in its _afterLoad() loads again all quote items (or children only), and attaches children to parents.

[engcom-Hotel]

Hi @samcleathero,

Thank you for reporting the issue.

We are successfully able to reproduce it on Magento 2.4-develop.

Steps followed to reproduce issue:

1. Added configurable and non-configurable products to the cart.

2. Print the $_item->getHasChildren() property on the $_items.

3. Observe the function output with pagination and without pagination for the cart.

4. $_item->getHasChildren() returns true when the pagination is not there for the cart and returns null when the cart is with pagination. (See the attached screenshots)

Conclusion: Item property should not change before and after pagination applied to the cart items.

Thanks

[github-jira-sync-bot]

✅ Jira issue https://jira.corp.magento.com/browse/AC-1735 is successfully created for this GitHub issue.