Appending array of map from model in firestore document in Swift - arrays

Question

I am trying to add to an array of maps in Firestore and getting the following error:
Terminating app due to uncaught exception 'FIRInvalidArgumentException', reason: 'Unsupported type: __SwiftValue'
This is my Model Class:
struct StringModel: Identifiable, Codable, Equatable, Hashable {
var id = UUID()
var cross: Int
var mains: Int
var name: String
var date: Date
}
struct UserDataModel: Identifiable, Codable {
#DocumentID public var id: String?
var uid: String
var strings: [StringModel]?
}
Am using the following function to update the value in firestore, however, it doesnt seem to work and throws the error:
#Published var newString = StringModel(cross: 50, date: Timestamp(), mains: 50, name: "")
func addString() {
db.document(uidStr).updateData(["strings" : FieldValue.arrayUnion([newString])]) { err in
if let err = err{
print("\(err)")
}
}
}
Firestore Datatbase
Any ideas how I can go about this? Thanks!

Answer 1

You can't append a Swift object to a Firestore array. You must convert the Swift object into a [String: Any] object. You can add a computed property to the model that outputs this for you.
struct StringModel: Identifiable, Codable, Equatable, Hashable {
var id = UUID()
var cross: Int
var mains: Int
var name: String
var date: Date
var firestoreData: [String: Any] {
return [
"id": id,
"cross": cross,
"mains": mains,
"name": name,
"date": date
]
}
}
func addString() {
db.document(uidStr).updateData(["strings" : FieldValue.arrayUnion([newString.firestoreData])]) { err in
if let err = err{
print("\(err)")
}
}
}