curl --request GET \
  --url https://api.meetcampfire.com/coa/api/v1/invoice/report/{id}/data \
  --header 'Authorization: <api-key>'

{
  "count": 5,
  "results": [
    {
      "client_id": 42,
      "client_name": "Acme Corp",
      "amount": 50000,
      "amount_paid": 30000,
      "Widget A::::amount": 25000,
      "Widget B::::amount": 25000,
      "filter_params": {
        "invoice__client_id": 42
      },
      "group_id": 123456,
      "id": 123456
    }
  ],
  "engine_used": "postgres",
  "pivot_result_fields": [
    "Widget A::::amount",
    "Widget B::::amount"
  ],
  "pivot_value_mappings": {
    "product_id": {
      "Widget A": 1,
      "Widget B": 2
    }
  }
}