How to remove a certain field from map cloud firestore? - swift

Question

I continue to develop a directory application and now I need to delete a specific line in the map from cloud firestore.There is my database:
screenshot
I need to remove field with key "2324141" or change its value.
I know about this method:
"2324141": FieldValue.delete()
But how do I get into the map and delete field or change the value?
thanks!
Here is my model of Object:
class ObjectInFB: Codable {
var objectFromPartsCatalogueListCode: String?
var countOfCurrentObjectInShoppingCart: Int = 1}
Here is func, where i save object in users shoppingBag:
func addToUserShoppingCartFB(user: User?, object: ObjectInFB, count: Int){
guard let user = user else { return }
let objectReadyToBeWriten = [
"UserEmail":"\(user.email!)",
"shoppingCart" : ["\(object.objectFromPartsCatalogueListCode!)" : FieldValue.increment(Int64(count))]] as [String : Any]
db.collection("users")
.document("\(user.uid)")
.setData(objectReadyToBeWriten, merge: true)
{ err in
if let err = err {
print("Error adding document: \(err)")
} else {}
}
}
And after the user in their cart in the application clicks "remove from cart" I want to delete an object from their cart in Firebase. I can only remove any field from the document, but how can I remove a field from the nested ShoppingCart?
func removeShoppingCartFB(object: ObjectInFB, user: User?){
db.collection("users").document(user!.uid).updateData([
"shoppingCart": ["\(object.objectFromPartsCatalogueListCode!)" : FieldValue.delete()],
]) { err in
if let err = err {
print("Error updating document: \(err)")
} else {
print("Document successfully updated")
}
}
}

Answer 1

If the goal is to delete a field within a map, it can be accessed through dot notation. For example suppose your structure looks like this
users
uid_0
UserEmail: "test#test.com"
shoppingCart (a map)
2324141: 10
122323424: 13
and we want to remove the 2324141 field. Here's the Swift code to do that
let myCollection = self.db.collection("users")
let myDoc = myCollection.document("uid_0")
myDoc.updateData( ["shoppingCart.2324141": FieldValue.delete(),
]) { err in
if let err = err {
print("Error updating document: \(err)")
} else {
print("Document successfully updated")
}
}