Swift URLRequest to Parse Platform REST API (JSON) & Decode into Struct - ios

Question

I am trying to use specific capabilities not available in the available iOS SDK for Parse Platform (Server), but that I know are available with the REST API. Specifically to use a DISTINCT query.
Using the Parse Dashboard and REST API client app on my dev computer (Rested.app), I have verified the following query completes as expected:
curl -X GET \
-H "X-Parse-Application-Id: someAppID" \
-H "X-Parse-Master-Key: someKey" \
-G \
--data-urlencode "distinct=TeeTime" \
http://somehost:1337/parse/aggregate/CompEntry
Which successfully returns data:
{
"results": [
{
"__type": "Date",
"iso": "2020-08-29T07:00:00.000Z"
},
{
"__type": "Date",
"iso": "2020-08-29T07:09:00.000Z"
}
] }
The original data is from, which has 3 rows, 2 of which share the same TeeTime:
And a screenshot of the output from the Rested.app:
Now I am trying to convert this for my Swift / iOS project.
I am trying to move the downloaded data into a new struct to represent the object(s), using the Codable/Decodable approach and matching the JSON property names. The code I have so far is below (placed some comments inline too). The Struct definitions occur in separate .swift files, but so long as outside the main ViewController definition.
struct TeeTimeData: Codable {
let results: [Results]
}
struct Results: Codable {
let __type: String
let iso: String // TODO: THIS SHOULD BE A DIFFERENT DATA TYPE - I HAVE PICKED HARDER DATA TYPE TO START WITH!
}
Then within the main ViewController struct:
class ViewController: UIViewController {
#IBAction func buttonGetTeeTimes(_ sender: UIButton) {
if let url = URL(string: "http://somehost:1337/parse/aggregate/CompEntry") {
var request = URLRequest(url: url)
request.addValue("someAppID", forHTTPHeaderField: "X-Parse-Application-Id")
request.addValue("someKey", forHTTPHeaderField: "X-Parse-Master-Key")
request.httpMethod = "GET"
let params = ["distinct": "TeeTime"] // TODO: THIS VAR IS NOT ACTUALLY BEING TIED TO THE REQUEST EITHER - 2nd PROBLEM...
let session = URLSession(configuration: .default)
let requestTask = session.dataTask(with: request) { (data, response, error) in
if error != nil {
print("API Error: \(error)")
}
if let dataUnwrap = data {
// TODO: MOVE THIS INTO NEW CLASS (DataModel, etc)
let decoder = JSONDecoder()
do {
let decodedData = try decoder.decode(TeeTimeData.self, from: dataUnwrap)
print(decodedData)
} catch {
print("Decode Error: \(error)")
}
}
}
requestTask.resume()
}
}
}
And the console output is:
Decode Error: keyNotFound(CodingKeys(stringValue: "__type", intValue:
nil), Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue:
"results", intValue: nil), _JSONKey(stringValue: "Index 0", intValue:
0)], debugDescription: "No value associated with key
CodingKeys(stringValue: "__type", intValue: nil) ("__type").",
underlyingError: nil))
My first guess is the 2 underscores, "__type", at the start of the property definition?

Answer 1

Answer provided by #Larme in the comments to the opening post. Contributions from #gcharita that my syntax should have worked if it was the same structure as the other tests I was performing (it wasn't - see below).
The error was occurring because the results being returned was a different JSON structure because the distinct=TeeTime filter wasn't being applied. So it was returning a JSON object with all the rows of data from the class, not those specified in my TeeTimeData struct object.
Appending ?distinct=TeeTime to the end of the URL string resolved the issue and returns:
Decoded data: TeeTimeData(results: [Parse_2.Results(__type: "Date",
iso: "2020-08-29T07:00:00.000Z"), Parse_2.Results(__type: "Date", iso:
"2020-08-29T07:09:00.000Z")])
It also means I no longer require the let params = ["distinct": "TeeTime"] code as well.