I'm trying to write an API endpoint for creating Redemptions in my app. 
In Rails, my model is such that Redemption has many Items (class_name: RedemptionItems).
Here's my POST Body, following what I assume is the correct JSONAPI Specification (since there is no explicit spec for creating parent and child records in one request).
{
  "data": {
    "type": "redemptions",
    "relationships": {
      "items": {
        "data": [{
            "type": "items",
            "attributes": { "offer_id": "1", "quantity": "2" }
          },
          {
            "type": "items",
            "attributes": { "offer_id": "1", "quantity": "3" }
          },
          {
            "type": "items",
            "attributes": { "offer_id": "123", "quantity": "3" }
          }
        ]
      }
    }
  }
}
I'm using JSONAPI::Resources. I have defined my JSONAPI::Resources thus:
class Platform::Api::Members::RedemptionItemResource < JSONAPI::Resource
  model_name 'Platform::RedemptionItem'
  has_one :redemption
end
class Platform::Api::Members::RedemptionResource < JSONAPI::Resource
  model_name 'Platform::Redemption'
  has_many :items, class_name: 'RedemptionItem'
end
It's currently giving me an inavlid links object error, which doesnt tell me anything on how I must improve my request body.
{
  "errors": [
    {
      "title": "Invalid Links Object",
      "detail": "Data is not a valid Links Object.",
      "code": "115",
      "status": "400"
    }
  ]
}
