Flatten request mapping hierarchy in RestKit

Question

With RestKit, I'm trying to create a request mapping that would convert a payment object into JSON. This object stores sub-payments, of which only one is valid. This valid payment is represented by the property selectedPayment. I think the typical approach for this is to use a relationship mapping however I don't want the selectedPayment to appear as a nested key. An example of the result of my current approach is below:

{
  "requestUserId" : "6",
  "payment" : {
    "selectedPayment" : {
      "amount" : "5",
      "id" : 70,
      "type" : "SOME_TYPE"
    }
  }
}

My desired output is the following:

{
  "requestUserId" : "6",
  "payment" : {
    "amount" : "5",
    "id" : 70,
    "type" : "SOME_TYPE"
  }
}

I have tried numerous options for my relationship mapping's destination key path: @root, @parent, "", nil. All of which have resulted in a crash (except "", which nests the selected payment under an empty key).

I could modify the attribute mappings of the request mapping that is used for selectedPayment to explicitly use @root or @parent but this would not be ideal as it would negatively affect other areas that mapping is used.

This seems like typical behaviour, converting a "deep" object representation into a "shallow" JSON representation, surely there is a straightforward way to do it?

Answer 1

Instead of using a relationship mapping, use key paths in your single mapping, navigate into the property and then extract the keys that you seeking.