Write and read ratings from firestore in Swift - swift

Question

I'm trying to have users submit star ratings and then have them stored under a collection within their document. I have the functions written which should do these things, getRatingsSubcollection, addTransactionRating, but I can't figure out how to place them in the structure so that they run for each user-submitted rating.
struct Rating: View {
#State var userCurrentRating: CGFloat = 0.0
var schools = ["North Avenue", "West Village", "Brittain"]
#State private var location = "West Village"
#State private var isUserRatingCurrent = true
#State private var currentRating: CGFloat = 0.0
var db: Firestore!
var body: some View {
NavigationView{
ScrollView {
VStack(spacing: 16) {
Divider()
Text("Choose a dining location:")
.bold()
Picker("Choose a dining location:", selection: $location) {
ForEach(schools, id: \.self) {
Text($0)
}
}
Text("Current Rating, \(currentRating)")
.bold()
if self.isUserRatingCurrent {
VStack {
RatingsViewCurrent(onDidRateCurrent: self.userDidRateCurrent, ratingCurrent: self.$userCurrentRating)
.frame(width: .infinity, height: 100, alignment: .center)
}
} else {
VStack {
RatingsViewCurrent(ratingCurrent: self.$currentRating)
.frame(width: .infinity, height: 100, alignment: .center)
if userCurrentRating == 0.0 {
Button("Rate") {
self.isUserRatingCurrent = false
}
}
}
}
}
}.navigationTitle("Add a Rating")
}
}
func userDidRateCurrent(_ ratingCurrent: Int) { print("ratingcurrent \(ratingCurrent)")
}
// [START restaurant_struct]
struct diningLocation {
let location: String
let currentRating: Float
let usualRating: Float
let totalRatings: Float
init(location: String, currentRating: Float, usualRating: Float, totalRatings: Float) {
self.location = location
self.currentRating = currentRating
self.usualRating = usualRating
self.totalRatings = totalRatings
}
}
let WestVillage = diningLocation(location: "West Village", currentRating: 4.65, usualRating: 2.9, totalRatings: 45.0)
// [END restaurant_struct]
struct Rating {
let rating: Float
}
func getRatingsSubcollection() {
// [START get_ratings_subcollection]
db.collection("RatingInformation")
.document("West Village")
.collection("ratings")
.getDocuments() { (querySnapshot, err) in
// ...
}
// [END get_ratings_subcollection]
}
// [START add_rating_transaction]
func addRatingTransaction(restaurantRef: DocumentReference, ratingCurrent: Float) {
let ratingRef: DocumentReference = restaurantRef.collection("ratings").document()
db.runTransaction({ (transaction, errorPointer) -> Any? in
do {
let restaurantDocument = try transaction.getDocument(restaurantRef).data()
guard var restaurantData = restaurantDocument else { return nil }
// Compute new number of ratings
let totalRatings = restaurantData["totalRatings"] as! Int
let newNumRatings = totalRatings + 1
// Compute new average rating
let usualRating = restaurantData["usualRating"] as! Float
let oldRatingTotal = usualRating * Float(totalRatings)
let newAvgRating = (oldRatingTotal + ratingCurrent) / Float(newNumRatings)
// Set new restaurant info
restaurantData["totalRatings"] = newNumRatings
restaurantData["usualRating"] = newAvgRating
// Commit to Firestore
transaction.setData(restaurantData, forDocument: restaurantRef)
transaction.setData(["rating": ratingCurrent], forDocument: ratingRef)
} catch {
// Error getting restaurant data
// ...
}
return nil
}) { (object, err) in
// ...
}
}
}