Could not save child: "Unknown entity type: Magento\Bundle\Model\Selection\Interceptor requested"

[faradey]

Preconditions and environment

• Magento version 2.4.6, 2.4.7, 2.4.8

Steps to reproduce

1. Create a module MyCompany/MyModule.

2. Add a plugin in the app/code/MyCompany/MyModule/etc/adminhtml/di.xml file:

   <type name="Magento\Framework\Model\AbstractModel">
       <plugin name="MyCompany\MyModule\Plugin\MagentoFramework\Model\AbstractModel"
               type="MyCompany\MyModule\Plugin\MagentoFramework\Model\AbstractModel"
               disabled="false" sortOrder="1000"/>
   </type>

3. Create the class MyCompany/MyModule\Plugin\MagentoFramework\Model\AbstractModel:

   <?php
   
   namespace MyCompany\MyModule\Plugin\MagentoFramework\Model;
   
   class AbstractModel
   {
       /**
        * @param \Magento\Framework\Model\AbstractModel $subject
        * @param mixed $result
        * @return \Magento\Framework\Model\AbstractModel
        */
       public function afterBeforeSave(
           \Magento\Framework\Model\AbstractModel $subject,
                                                  $result
       ) {
          $a=1;
   
           return $result;
       }
   
       /**
        * @param \Magento\Framework\Model\AbstractModel $subject
        * @return void
        */
       public function beforeAfterSave(
           \Magento\Framework\Model\AbstractModel $subject
       ) {
           $a=1;
       }
   
       public function beforeBeforeDelete(
           \Magento\Framework\Model\AbstractModel $subject
       ) {
           $a=1;
       }
   }

4. Execute bin/magento setup:upgrade.

5. Create/update a bundle product.

Expected result

The product is saved without errors.

Actual result

When saving the product, we get the error:
Could not save child: "Unknown entity type: Magento\Bundle\Model\Selection\Interceptor requested"

Additional information

No response

Release note

No response

Triage and priority

• 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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[m2-assistant]

Hi @engcom-Hotel. Thank you for working on this issue.
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[engcom-Hotel]

Hello @faradey,

Thanks for the report and collaboration!

We have tried to reproduce the issue in the latest development branch i.e. 2.4-develop and the issue has been reproducible for us. But it seems to us an expected behaviour.

Official Documentation Links

Adobe Commerce DevDocs - Plugin Limitations: https://developer.adobe.com/commerce/php/development/components/plugins/#limitations

This page specifically states:

Plugins cannot be used on:

Final classes
Final methods
Non-public methods
__construct
Virtual types
Objects that are instantiated before Magento\Framework\Interception is bootstrapped
Plugins should not be used on:

Abstract classes
Methods called from classes that are not a part of the interception system

Why Plugins Should Not Be Created for Abstract Classes

Plugins Attach to Specific Implementations:

Plugins in Magento 2 are designed to modify or extend the behavior of concrete class methods. Since abstract classes do not provide concrete method implementations (only declarations), plugins cannot operate on abstract methods.

Abstract methods must be implemented in a subclass, and it’s the subclass's implementation that gets executed, not the abstract class’s declaration.

Abstract Classes and Code Behavior:

An abstract class acts as a blueprint for concrete classes. Plugins cannot be reliably attached to them because there's no guarantee the abstract class's methods will be called in the same way by all implementations.

Let us know in case we missed anything.

Thanks

[faradey]

Hi,

thank you for your explanation. I understand your recommendations. However, the issue isn't even with the AbstractModel class itself, but rather with how the class that saves the bundle product is specifically written. Other product types save correctly, and plugins work fine for them, but not for bundle products. This is something that needs attention.

By the way, I couldn't find any mention of abstract classes in the link you provided earlier.

And I don't see anything wrong with wanting to perform certain actions before or after saving any entity. I could have used a preference for the AbstractModel class, but a preference wouldn't work specifically for the adminhtml scope, as I require.

Ultimately, the problem exists, and it's clearly due to the bundle product saving process violating Magento's flow.