FInal version of converting function

QueryReason.re

type metricCount = {type_: string};

type metricWithLabel = {
  type_: string,
  label: string
};

let createCountWithLabel = (label) : metricWithLabel => {type_: "COUNT", label};

let countMetric: metricCount = {type_: "COUNT"};

module MetricEncoder = {
  let encodeCountMetricWithLabel = (m: metricWithLabel) =>
    Json.Encode.(object_([("type", string(m.type_)), ("label", string(m.label))]));
  let encodeCountMetric = (m: metricCount) => Json.Encode.(object_([("type", string(m.type_))]));
};

let transformToCount20 = (oldJson) => {
  let label = Json.Decode.(oldJson |> optional(field("label", string)));
  switch label {
  | Some(v) => createCountWithLabel(v) |> MetricEncoder.encodeCountMetricWithLabel
  | None => countMetric |> MetricEncoder.encodeCountMetric
  }
};