Hi @gustavosolomon. Thank you for your report.
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I found that if I send "custom_attributes" data as object instead of array of objects, it works..

So if I send like this, it works:

{
    "custom_attributes": {
        "manufacturer": "test"
    }
}

that's because $key (referenced above in the issue), in this case, will be the attribute code itself.

but if I send like this, it doesn't:

{
    "custom_attributes": [
        {
            "attribute_code": "manufacturer",
            "value": "test"
        }
    ]
}

because $key in this case, will be an auto-assigned array key (0 => []).

so that's why I think we should change the runCustomAttributePreprocessors call and use $customAttributeCode (which is always the attribute code, instead of $key (which can be an auto-assigned array key)

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Hello @gustavosolomon,

Thanks for the report and collaboration!

We have referred to the redocly on the below URL:

https://developer.adobe.com/commerce/webapi/rest/quick-reference/

According to the documentation of API V1/products we should pass the custom attributes in the below way only:

{
    "custom_attributes": [
        {
            "attribute_code": "manufacturer",
            "value": "test"
        }
    ]
}

Please refer to the below screenshot for reference:

Thanks

Hi @engcom-Hotel ! Thanks for your review.

Yes, that seems correct. So let's just stick with this API documentation example.

And that's the one where the described problem happens.

Maybe I could send a PR so you can better visualize where the problem occurs?

Sure @gustavosolomon,

We will wait for the PR.

Hey @engcom-Hotel, I sent the PR so you can take a look.

Some points to look at while analyzing the changes:

1. I changed the way processCustomAttribute function works, because there's no point in return $customAttributeValue inside a array since will not be used ($customAttributeValue it will be processed in the line after) by $this->runCustomAttributePreprocessors($customAttributeCode, $customAttribute);. This function will process the attribute value, and then, in the line after $customAttributeValue = $customAttribute[AttributeValue::VALUE]; will get the processed attribute value.

And since processCustomAttribute is a private function, it won't affect anything else, anyone has implemented a custom version of this class must have been copied the entire processCustomAttribute function and it's call.

Reference (This is from my PR):

2. Where I changed from $key to $attributeCode, is because we are dealing with attribute codes. And I only did this change to a an Interface because I checked no class in Magento is implementing this interface.

3. There was some doc block space changes, which I don't know would be allowed to pass, so I can reverse this specific change, if necessary.

Thanks @gustavosolomon for the PR,

I am marking this issue as a feature request, also suggesting to check the BIC failures on the below link for your PR and fix those:

https://public-results-storage-prod.magento-testing-service.engineering/reports/magento/magento2/pull/38635/78b4d9e7f55cef44089ce796e055a682/SemanticVersionChecker/report-magento2.html

Thanks

Hi @engcom-Hotel, thanks for the update.

I just sent another PR, which should be good to go.

Can you please take a look? Thanks!