Post Request in Kotlin - json

Question

I'm trying to do a post request in Android Studio written in Kotlin
I'm posting a JSON object to our server and then the server is returning a JSON object back. But what I'm doing here is decoding the response body as a string and then converting it into the data structure we need. I'm sure there is a better and simpler way to do what I need done.
My current code works but the major issue I'm having is formatting the string if our objects have nested objects which is why I want to figure out a better way to turn the response body into a json object.
I'm not too familiar with many request libraries for kotlin but I have looked into okhttp3 but I'm not sure how to post a json object, attach headers and decode the response body into a json object.
I know for okhttp3 I need to convert the json object to a string to post other than that I'm lost.
Breakdown of what's needed:
Post JSON Object To Server
Send Headers With Post Request
Decode Response Body into JSON Object/ Kotlin Equivalent
Simplify What I'm Trying to Do if Possible
This is the current code I have
private fun postRequestToGetDashboardData() {
val r = JSONObject()
r.put("uid", muid)
r.put("token", mtoken)
SendJsonDataToServer().execute(r.toString());
}
inner class SendJsonDataToServer :
AsyncTask<String?, String?, String?>() {
override fun onPostExecute(result: String?) {
super.onPostExecute(result)
if (result.equals(null)) {
val t = Toast.makeText(this#Home, "No devices to display", Toast.LENGTH_LONG)
t.setGravity(Gravity.CENTER, 0, 0)
t.show()
} else {
intentForUnique.putExtra("FirstEndpointData", result)
var list = handleJson(result)
adapter.submitList(list)
dashboardItem_list.adapter = adapter
adapter.notifyDataSetChanged();
dashboardItem_list.smoothScrollToPosition(0);
}
}
override fun doInBackground(vararg params: String?): String? {
val JsonDATA = params[0]!!
var urlConnection: HttpURLConnection? = null
var reader: BufferedReader? = null
try {
val url = URL("URL");
urlConnection = url.openConnection() as HttpURLConnection;
urlConnection.setDoOutput(true);
urlConnection.setRequestMethod("POST");
urlConnection.setRequestProperty("Content-Type", "application/json");
urlConnection.setRequestProperty("Authorization", mtoken);
urlConnection.setRequestProperty("Accept", "application/json");
val writer: Writer =
BufferedWriter(OutputStreamWriter(urlConnection.getOutputStream(), "UTF-8"));
writer.write(JsonDATA);
writer.close();
val inputStream: InputStream = urlConnection.getInputStream();
if (inputStream == null) {
return null;
}
reader = BufferedReader(InputStreamReader(inputStream))
var inputLine: String? = reader.readLine()
if (inputLine.equals("null")) {
return null
} else {
return inputLine
}
} catch (ex: Exception) {
Log.e(TAG, "Connection Failed", ex);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (ex: Exception) {
Log.e(TAG, "Error closing stream", ex);
}
}
}
return null
}
}
private fun handleJson(jsonString: String?): ArrayList<SensorData> {
val jsonArray = JSONArray(jsonString)
val list = ArrayList<SensorData>()
var x = 0
while (x < jsonArray.length()) {
val jsonObject = jsonArray.getJSONObject(x)
list.add(
SensorData(
jsonObject.getInt("deviceId"),
// jsonObject.getString("deviceName"),
jsonObject.getInt("battery"),
jsonObject.getString("dateTime"),
jsonObject.getInt("airValue"),
jsonObject.getInt("waterValue"),
jsonObject.getInt("soilMoistureValue"),
jsonObject.getInt("soilMoisturePercent")
)
)
x++
}
return list
}
So the json data being returned back is an array of this structure (our backend is written in Go)
type Device struct {
DeviceID int `bson:"deviceId" json:"deviceId"`
Battery int `bson:"battery" json:"battery"`
DateTime time.Time `bson:"dateTime" json:"dateTime"`
AirValue int `bson:"airValue" json:"airValue"`
WaterValue int `bson:"waterValue" json:"waterValue"`
SoilMoistureValue int `bson:"soilMoistureValue" json:"soilMoistureValue"`
SoilMoisturePercent int `bson:"soilMoisturePercent" json:"soilMoisturePercent"`
}