Cloud Firestore error while trying to retrieve List

Question

I started working with Cloud Firestore in a personal project and have been facing an issue trying to retrieve a List from a Document while I still managed to receive some data from the backend, it's not that precise while checking the DB.

Collection
 DocumentN
     -otherStuff
     -usermatches:                <---- This is an array  
          (0): 
             -Score:0
             -Id:123 
          (1): 
             -Score:1
             -Id:456

Schema

I've been trying alot and the class below is me solving momentarily the Error HashMap cannot be cast to parameter.. but I do not know how to really achieve what i need, if you have any feed back or have any recommendations pls tell me

Backend.kt

docRef = db.collection("userdata").document(user.user_id)
                docRef.get()
                        .addOnCompleteListener { task ->
                            if (task.isSuccessful) {

                                val document: DocumentSnapshot = task.result

                                val cedula = document.data!!["cedula"] as Long
                                val points = document.data!!["points"] as Long
 //                                    val usermatches = document.data!!["usermatches"] as HashMap<String, Any>
                                val alias = document.data!!["username"] as String

//                                     val usermatches = document.toObject(Usermatches::class.java)

                                val map: MutableMap<String, Any>? = document.data
                                for (entry in map!!.entries) {
                                    if (entry.key == "usermatches") {

                                        val list = entry.value as ArrayList<Any>

                                        for (each in list){

                                            for (entry2 in  each as HashMap<String, Any>){

                                                var home_score: Long = 0
                                                var winner: Long = 0
                                                var userchanged: Boolean = true
                                                var id: String = ""
                                                var away_score: Long = 0

                                                val usermatch = Usermatches(home_score, away_score, id, userchanged, winner)

                                                when {
                                                    entry2.key == "away_score" -> {
                                                        away_score = entry2.value as Long

                                                        usermatch.away_score = away_score
//                                                            println(away_score)
                                                    }
                                                    entry2.key == "home_score" -> {

                                                        home_score = entry2.value as Long
                                                        usermatch.home_score = home_score
//                                                            println(home_score)
                                                    }
                                                    entry2.key == "id" -> {
                                                        id = entry2.value as String
                                                        usermatch.id = id
//                                                            println(id)
                                                    }
                                                    entry2.key == "userchanged" -> {
                                                        userchanged = entry2.value as Boolean
                                                        usermatch.userchanged = userchanged
//                                                            println(userchanged)
                                                    }
                                                    entry2.key == "winner" -> {
                                                        winner = entry2.value as Long
                                                        usermatch.winner = winner
//                                                            println(winner)
                                                    }

                                                }
                                                mDisposable.add(usermatchesViewModel.insert(Usermatches(home_score, away_score, id, userchanged, winner))
                                                    .subscribeOn(Schedulers.io())
                                                    .subscribe{ println("Checking")})

                                            }
                                        }
                                    }
                                }

                            } else {
                                Log.d(TAG, "Error getting Usermatches ", task.exception)
                            }

                        }
            })

Usermatches Data Class

@Entity
data class Usermatches(var home_score: Long,
                   var away_score: Long,
                   @ColumnInfo(name = "usermatches_id") var id: String,
                   var userchanged: Boolean,
                   var winner: Long) {
    @PrimaryKey(autoGenerate = true)
    var num_id: Long = 0
 }

Answer 1

As @Alex Mamo pointed out, it was indeed a HashMap

What I was doing in the above code snipet was close to how I actually solved the problem.

I was initializing my Object inside the third for loop and was making it hold imprecise information from the Firestore DB.

Solution:

docRef = db.collection("userdata").document(user.user_id)
                docRef.get()
                        .addOnCompleteListener { task ->
                            if (task.isSuccessful) {

                                val document: DocumentSnapshot = task.result

                                val cedula = document.data!!["cedula"] as Long

                                val points = document.data!!["points"] as Long

                                val alias = document.data!!["username"] as String

                                val map: MutableMap<String, Any>? = document.data
                                for (entry in map!!.entries) {
                                    if (entry.key == "usermatches") {

                                        val list = entry.value as ArrayList<Any>

                                        var home_score: Long = 0
                                        var winner: Long = 0
                                        var userchanged: Boolean = true
                                        var id: String = ""
                                        var away_score: Long = 0

                                        for (each in list){

                                            val usermatch = Usermatches(home_score, away_score, id, userchanged, winner)

                                            for (entry2 in  each as HashMap<String, Any>){

                                                when {
                                                    entry2.key == "away_score" -> usermatch.away_score = entry2.value as Long
                                                    entry2.key == "home_score" -> usermatch.home_score = entry2.value as Long
                                                    entry2.key == "id" -> usermatch.id = entry2.value as String
                                                    entry2.key == "userchanged" -> usermatch.userchanged = entry2.value as Boolean
                                                    entry2.key == "winner" -> usermatch.winner = entry2.value as Long
                                                }

                                            }

                                            println("$usermatch")
                                            mDisposable.add(usermatchesViewModel.insert(usermatch)
                                                    .subscribeOn(Schedulers.io())
                                                    .subscribe{println("Checking")})
                                        }
                                    }
                                }

                            } else {
                                Log.d(TAG, "Error getting Usermatches ", task.exception)
                            }
                        }
            })

Answer 2

-usermatches: <---- This is an array

Is not! It's true that if an object is stored in the database as an array, entry.value returns an ArrayList and not an array, but in your case, usermatches is a map which in terms contains other maps, 0, 1 and so on. That's why you also get that error. So in order to solve this, you need to iterate over usermatches map twice, once to get the maps and second to get the values whithin those maps.