Magento 2 SOAP exception: missing values for message placeholders

Question

When calling the Magento2 SOAP API to create a new product, I get a generic error message saying 'Invalid product data: %1'. I was hoping that the Magento2 API would throw better exceptions than Magento1 but unfortunately they seem to be just as awful and generic.

Is there any way to get the actual exception somewhere? Or do we just trial and error?

Answer 1

In general

In addition to "message" element, response has "parameters" element, which contains data for placeholders in the message. This approach allows customization of actual message shown to the end user, while still allows usage of parameters in the custom message. For example, if you do not have enough permissions to access some resource you get:

{
    "message": "Consumer is not authorized to access %resources",
    "parameters":
    {
        "resources": "Magento_Catalog::products"
    }
}

It is also possible to get full exception stack trace by enabling developer mode in Magento (by uncommenting SetEnv MAGE_MODE developer in the root .htaccess).

Described behavior is uniform in REST and SOAP.

Issue in SOAP

Described issue in SOAP (internal issue MAGETWO-46088) is reproducible in case when exception in the underlying service is thrown in the way:

throw new \Magento\Framework\Exception\CouldNotSaveException(
    __('Invalid product data: %1', implode(',', $validationResult))
);

It would be rendered correctly if parameters were passed as an associative array like:

throw new \Magento\Framework\Exception\CouldNotSaveException(
    __('Invalid product data: %message', ['message' => implode(',', $validationResult)])
);

Workaround (until issue is fixed in core)

To get parameters rendered properly you have to modify core code (not possible via plugin because this SOAP fault objects are instantiated using new).

In this method \Magento\Webapi\Model\Soap\Fault::_getParametersXml replace

if (is_string($parameterName) && (is_string($parameterValue) || is_numeric($parameterValue))) {

with this

if ((is_string($parameterName) || is_numeric($parameterName))
    && (is_string($parameterValue) || is_numeric($parameterValue))
) {
    if (is_numeric($parameterName)) {
        $parameterName++;
    }