Extending quote item with extension attributes - problem with load/save of attributes

[bartoszkubicki]

Summary (*)

Recently, I was trying to extend quote item with extension attributes. I needed it inside cart and checkout. So there are actually two ways for loading and persisting extension attributes along extended model.

• First is creating plugins on repository of entity which has these new attributes.
  For CartItemRepository this maybe would work for webapi - inside cart, checkout quote items are loaded in other ways - sometimes from qoute - by items collection, sometimes by directly loading model. It turns out that CartItemRepository is not very useful in frontend. Here comes also other grave problem - service contracts vs ,methods loading/returing/requiring concret implementations - many cases for quote and quote item.
• Second way is adding handles to ExtensionPool, but it requires resource model using EntityManager, which is is not recommended . Despite of this for qoute item it is imposible, beacause, crud operations are performed in 'old-fashioned' way.

Finally, to perform crud operations on cart and checkout, with main logic in subtotals I ended up with plugins for three classes and override 5 methods - quote items are not loaded in any consistent way.

Examples (*)

Hard to provide - generally module doesn't seem to follow general guidelines from Magento.

Proposed solution

Clean up crud operations for quote and quote item, so service contract are used more widely on frontend, so we are not relying on implementations, but on contracts.

[magento-engcom-team]

Hi @bartoszkubicki. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

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Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

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For more details, please, review the Magento Contributor Assistant documentation.

@bartoszkubicki do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

[magento-engcom-team]

Hi @engcom-backlog-nazar. Thank you for working on this issue.
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[ghost]

Hi @bartoszkubicki thank you for you report, It will be processed faster if you move this to https://github.com/magento/community-features