Magento 2.4 Rest API Error: Method's return type must be specified using @return annotation

Question

I had been trying to use rest api for getting Configurable Products (Child products) using the rest API - https:url//rest/V1/configurable-products/sku/children

But, I am getting this framework error - "Method's return type must be specified using @return annotation. See Magento\Catalog\Model\ResourceModel\Product\Collection\Interceptor::load()"

Log Trace:

"trace": "#0 /var/www/html/vendor/magento/framework/Reflection/TypeProcessor.php(291): Magento\Framework\Reflection\TypeProcessor->getMethodReturnAnnotation(Object(Laminas\Code\Reflection\MethodReflection))\n#1 /var/www/html/vendor/magento/framework/Reflection/MethodsMap.php(180): Magento\Framework\Reflection\TypeProcessor->getGetterReturnType(Object(Laminas\Code\Reflection\MethodReflection))\n#2 /var/www/html/vendor/magento/framework/Reflection/MethodsMap.php(115): Magento\Framework\Reflection\MethodsMap->getMethodMapViaReflection('Magento\\Catalog...')\n#3 /var/www/html/vendor/magento/framework/Reflection/DataObjectProcessor.php(83): Magento\Framework\Reflection\MethodsMap->getMethodsMap('Magento\\Catalog...')\n#4 /var/www/html/vendor/magento/framework/Reflection/CustomAttributesProcessor.php(76): Magento\Framework\Reflection\DataObjectProcessor->buildOutputDataArray(Object(Magento\Catalog\Model\ResourceModel\Product\Collection\Interceptor), 'Magento\\Catalog...')\n#5 /var/www/html/vendor/magento/framework/Reflection/CustomAttributesProcessor.php(53): Magento\Framework\Reflection\CustomAttributesProcessor->convertCustomAttribute(Object(Magento\Framework\Api\AttributeValue), '\\Magento\\Catalo...')\n#6 /var/www/html/generated/code/Magento/Framework/Reflection/CustomAttributesProcessor/Proxy.php(95): Magento\Framework\Reflection\CustomAttributesProcessor->buildOutputDataArray(Object(Magento\Catalog\Model\Product\Interceptor), '\\Magento\\Catalo...')\n#7 /var/www/html/vendor/magento/framework/Reflection/DataObjectProcessor.php(107): Magento\Framework\Reflection\CustomAttributesProcessor\Proxy->buildOutputDataArray(Object(Magento\Catalog\Model\Product\Interceptor), '\\Magento\\Catalo...')\n#8 /var/www/html/vendor/magento/framework/Webapi/ServiceOutputProcessor.php(118): Magento\Framework\Reflection\DataObjectProcessor->buildOutputDataArray(Object(Magento\Catalog\Model\Product\Interceptor), '\\Magento\\Catalo...')\n#9 /var/www/html/vendor/magento/framework/Webapi/ServiceOutputProcessor.php(78): Magento\Framework\Webapi\ServiceOutputProcessor->convertValue(Array, '\\Magento\\Catalo...')\n#10 /var/www/html/vendor/magento/module-webapi/Controller/Rest/SynchronousRequestProcessor.php(97): Magento\Framework\Webapi\ServiceOutputProcessor->process(Array, 'Magento\\Configu...', 'getChildren')\n#11 /var/www/html/vendor/magento/module-webapi/Controller/Rest.php(188): Magento\Webapi\Controller\Rest\SynchronousRequestProcessor->process(Object(Magento\Framework\Webapi\Rest\Request\Proxy))\n#12 /var/www/html/vendor/magento/framework/Interception/Interceptor.php(58): Magento\Webapi\Controller\Rest->dispatch(Object(Magento\Framework\App\Request\Http))\n#13 /var/www/html/vendor/magento/framework/Interception/Interceptor.php(138): Magento\Webapi\Controller\Rest\Interceptor->___callParent('dispatch', Array)\n#14 /var/www/html/vendor/magento/framework/Interception/Interceptor.php(153): Magento\Webapi\Controller\Rest\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))\n#15 /var/www/html/generated/code/Magento/Webapi/Controller/Rest/Interceptor.php(23): Magento\Webapi\Controller\Rest\Interceptor->___callPlugins('dispatch', Array, Array)\n#16 /var/www/html/vendor/magento/framework/App/Http.php(116): Magento\Webapi\Controller\Rest\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))\n#17 /var/www/html/vendor/magento/framework/App/Bootstrap.php(264): Magento\Framework\App\Http->launch()\n#18 /var/www/html/pub/index.php(33): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http\Interceptor))\n#19 {main}" }

Upon Investigation, I found that - In vendor\magento\module-configurable-product\Model\LinkManagement.php has the function "public function getChildren($sku)". When I change the following line (104) -
$this->dataObjectHelper->populateWithArray($productDataObject, $attributes, \Magento\Catalog\Api\Data\ProductInterface::class);

to

$this->dataObjectHelper->populateWithArray($productDataObject,
[], \Magento\Catalog\Api\Data\ProductInterface::class);

There is no API error anymore, But the API output looks like -

[
    {
        "sku": null,
        "status": 1,
        "product_links": [],
        "tier_prices": []
    },
    {
        "sku": null,
        "status": 1,
        "product_links": [],
        "tier_prices": []
    },
    {
        "sku": null,
        "status": 1,
        "product_links": [],
        "tier_prices": []
    },
    ...
]

With no sku info.

What could be the issue here, that I am missing?

Answer 1

Found the issue. In the API function call getChildren, In the attribute loop, One of the attribute value was returning as an Object instead of attribute value, which was causing the break up of the code. Not sure, why it was throwing this annotation error, Need to investigate further, But, I added a patch to the code, to check, If the attribute value is an Object, skip that attribute.

Answer 2

You are receiving this error from this file - vendor/magento/framework/Reflection/TypeProcessor.php::getMethodReturnAnnotation, which throws an InvalidArgumentException.

$this->dataObjectHelper->populateWithArray() calls the _setDataValues() method, which in turn calls the setComplexValue() method. The setComplexValue() method ultimately calls the getMethodReturnAnnotation() method by calling the getMethodReturnType() method.

No error is thrown when you pass the $attributes parameter as an empty array because _setDataValues() loops over the attributes array, which is skipped.

A debugger like xdebug can help to easily debug the issue. You should add breakpoints in the flow mentioned above to detect the exact issue.