The documentation for the FuelSDK-Ruby gem says that you can use the Put method to do an upsert. However, this method doesn't appear to be implemented. Is there a way to do an upsert using the FuelSDK-Ruby gem?
Here's what the wiki says:
Support for single request to Add/Update:A single request can be made which will create the object if one doesn't already or update one if it does. This works for Subscriber, DataExtension::Row, and List objects using the Put method.