Decodable not working with non empty array - swift

Question

I'm using this library which has created non-empty collections like arrays, dictionaries and strings. https://github.com/pointfreeco/swift-nonempty
When I decode to the non-empty array I get the following error
Swift.DecodingError.typeMismatch(Swift.Dictionary, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "poiList", intValue: nil)], debugDescription: "Expected to decode Dictionary but found an array instead.", underlyingError: nil))
This is my structure
struct LocationCarModel: Codable {
// MARK: - Properties
var poiList: NonEmptyArray<PointOfInterest>
// MARK: - PointOfInterest
struct PointOfInterest: Codable {
var id: Int
var coordinate: Position
var fleetType: String
let numberPlate = "HCD837EC"
let model: String = "Tesla S"
let fuel: Double = 0.9
}
}
This is the response I'm getting https://fake-poi-api.mytaxi.com/?p2Lat=53.394655&p1Lon=9.757589&p1Lat=53.694865&p2Lon=10.099891
and this how I'm decoding it.
public extension Decodable {
static func parse(from item: Any?, strategy: JSONDecoder.KeyDecodingStrategy = .useDefaultKeys) -> Self? {
guard let data = self.data(from: item) else {
return nil
}
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = strategy
do {
let result = try decoder.decode(Self.self, from: data)
return result
} catch {
debugPrint(error)
return nil
}
}
private static func data(from item: Any?) -> Data? {
switch item {
case let data as Data:
return data
case let string as String:
return string.data(using: .utf8)
case .some(let item):
return try? JSONSerialization.data(withJSONObject: item, options: [])
case nil:
return nil
}
}
}
and the line to decode using the above function is
let model = LocationCarModel.parse(from: data)
Changing poiList to the standard swift array then no error occurs.
Any ideas how I can solve this issue? Any help would be appreciated. Thank you in advance.

Answer 1

You need to have your own init(from:) for the top struct since JSONDecoder doesn't understand NonEmpty and how to initialise it. Apart from the init I also added coding keys and a new error
enum DecodeError: Error {
case arrayIsEmptyError
}
struct LocationCarModel: Codable {
var poiList: NonEmpty<[PointOfInterest]>
enum CodingKeys: String, CodingKey {
case poiList
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let array = try container.decode([PointOfInterest].self, forKey: .poiList)
guard let first = array.first else {
throw DecodeError.arrayIsEmptyError
}
poiList = NonEmptyArray(first, array)
}
//...
}

Answer 2

You can try
struct Root: Codable {
let poiList: [PoiList]
}
// MARK: - PoiList
struct PoiList: Codable {
let id: Int
let coordinate: Coordinate
let fleetType: String
let heading: Double
}
// MARK: - Coordinate
struct Coordinate: Codable {
let latitude, longitude: Double
}
let res = try? JSONDecoder().decode(Root.self,from:data)
print(res)