Trying to get data from firebase Swift - ios

Question

Ok, I have a function that has to find the average of the ratings, so I store the total amount of ratings and a total sum of ratings in my firebase (which works fine). I am trying to retrieve the data, but it seems that it doesn't even enter the codeblock of the .observeSingleEvent I am using the same approach when trying to update the values, which means I get them and I add the new rating to them and then I use the code below to update the values:
let ratingObject = [
"uid" : (user?.uid)! as String,
"totalRatings" : newRating as Int,
"amountOfRatings" : newAmountOfRating as int
] as [String : Any]
dbRef.setValue(ratingObject)
It doesn't give an error and I am just lost
I tried to do it based on this tutorial: https://www.youtube.com/watch?v=JV9Oqyle3iE
The answers given in this thread : how parsing Firebase FDatasnapshot json data in swift are just crashing the app
private func FindAverage(uid: String) -> Int {
var totalRatings = 0
var amountOfRatings = 1
let dbRef = Database.database().reference().child("ratings").child(uid)
dbRef.observeSingleEvent(of: .value, with: { snapshot in
let dict = snapshot.value as? [String:Any]
totalRatings = dict?["totalRatings"] as? Int ?? 0
amountOfRatings = dict?["amountOfRatings"] as? Int ?? 1
}){ (error) in
print(error.localizedDescription)
}
return((Int)(totalRatings/amountOfRatings))
}
Database structure
Any tips and help is very appreciated!

Answer 1

You are trying to return value out of completion handler.
Your function should be like:
private func findAverage(byUid uid: String, completion: #escaping (_ average: Int) -> Void) {
// ...
dbRef.observeSingleEvent(of: .value, with: { snapshot in
guard let dict = snapshot.value as? [String: Any] else {
return
}
totalRatings = dict["totalRatings"] as? Int ?? 0
amountOfRatings = dict["amountOfRatings"] as? Int ?? 1
completion((Int)(totalRatings / amountOfRatings))
})
}
Something like this, check Swift docs (about completion handlers etc.).

Answer 2

Try below code:
private func FindAverage(uid: String) -> Int {
var totalRatings = 0
var amountOfRatings = 1
let dbRef = Database.database().reference().child("ratings").child(uid)
dbRef.observeSingleEvent(of: .value, with: { snapshot in
if snapshot.exists() {
guard let dict = snapshot.value as? [String: Any] else {
return
}
totalRatings = dict?["totalRatings"] as? Int ?? 0
amountOfRatings = dict?["amountOfRatings"] as? Int ?? 1
}
}){ (error) in
print(error.localizedDescription)
}
return((Int)(totalRatings/amountOfRatings))
}