Configurable Product Links Validation Bug when int value is 0

[davidverholen]

Preconditions

1. Magento 2.4-develop
2. Attribute with Source Model having 0 as one value
3. Create a simple Product with attribute value 0 selected

Steps to reproduce

1. Create configurable containing the simple product via REST Api

Expected result

1. Configurable Product is created with the linked simple product

Actual result

1. Exception thrown: Product with id "%1" does not contain required attribute "%2"."

The validation of the product links attributes from the configurable-product module is not type-safe which leads to a validation error when the value is (int)0
See: https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/ConfigurableProduct/Model/Plugin/ProductRepositorySave.php#L103

[davidverholen]

when it's confirmed I can provide a small pr just making the validation type safe or using the more suited hasData() here

[davidverholen]

update: it does not happen when saving the product in the backend because the problem is in a Plugin on the ProductRepository which is not used for saving the Product in the Adminhtml Save Controller

[davidverholen]

update: also some interesting behavior / bug: if you update the product via PUT request and do not specify type_id: configurable in the payload, the validation is not triggered since the product is not considered a configurable product here: https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/ConfigurableProduct/Model/Plugin/ProductRepositorySave.php#L60

[magento-engcom-team]

Hi @davidverholen
We can not reproduce the issue as you describe.
Please share an install script, how do you add the attribute and share you api request.
Thanks

[davidverholen]

Ok, I've created a small module config-bug.tar.gz

• Installed it in a fresh Installation of the OS Edition 2.2.2
• Added an Integration with Admin permission
• Created a simple Product with Value Zero for "New Attribute"
• try to create a new configurable product for the simple via Rest API:
  POST /V1/products
  Payload:

{
  "product": {
    "sku": "config",
    "name": "config",
    "status": 1,
    "type_id": "configurable",
    "attribute_set_id":4,
    "extension_attributes": {
      "configurable_product_options": [
        {
          "attribute_id": 133,
          "label": "New Attribute",
          "values": [
            {
              "value_index": "0"
            }
          ]
        }
      ],
      "configurable_product_links":[
        1
      ]
    }
  }
}

Result:

{"message":"Product with id \"%1\" does not contain required attribute \"%2\".","parameters":["1","new_attribute"]}

while the catalog_product_entity_int table also contains the correct value 0 for the attribute

[magento-engcom-team]

@davidverholen, thank you for your report.
We've acknowledged the issue and added to our backlog.

[davidverholen]

found this behavior in 2 more places: (since for some reason empty("0") evaluates to true in php):

When adding a product to cart with a "0" configuration chosen:
https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php#L857

When having a product in cart with a "0" configuration chosen
https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php#L955

as a first step, I think, it would be useful to extract the validation logic for the configurable options