Looping through nodes from Firebase Real-time database in Android Studio with Kotlin

Question

Working with Android Studio and firebase the link below shows the structure of our database.

Also added copy-pasted how the json file of the structure looks like.

https://i.stack.imgur.com/X3vkz.png

 "Events" : {
"-MxoB2kU8Okx0gFbnEIx" : {
  "addGoogleMaps" : true,
  "address" : "Gjuterivägen 3",
  "bringAlcohol" : false,
  "date" : "WEDNESDAY 23 FEBRUARY 2022",
  "description" : "Fest på holma",
  "endTime" : "End Time: 22:15",
  "maxAttendees" : 6,
  "overallsOn" : true,
  "ownerEmail" : "[email protected]",
  "plusOne" : false,
  "startTime" : "Start Time: 06:15",
  "title" : "Fest hos Mange"
},

Eventually there would be 50 events like this up in the database at the same time and what I need to do is loop through them all, without knowing their node-name and collect what i need.

Question:

With Kotlin, how can I access each child in Events without using their String path in a loop and take the following variables from each individual child:

Title, Location, and Date.

With these I need to instantiate an object that would represent that child and then put it in :

private val events = mutableListOf<Event>()?

I edited the entire question and I hope this is more understandable than previous time. Thanks!

Answer 1

Have you tried something like this:

mDatabase.child("Events").get().addOnSuccessListener {
    Log.i("firebase", "Got events: ${it}")
}.addOnFailureListener{
    Log.e("firebase", "Error getting data", it)
}

Generally it is recommended to use ValueEventListener instead of get() though: https://firebase.google.com/docs/database/android/read-and-write#read_data_once

Answer 2

Thanks to Frank Van Puffelen(in a comment) linked something very useful which seems to work the way I want!

https://firebase.google.com/docs/database/android/lists-of-data#read_and_write_lists

Here is the solution:

val database = FirebaseDatabase.getInstance().getReference("Events")
database.addValueEventListener(object : ValueEventListener {
        override fun onDataChange(dataSnapshot: DataSnapshot) {
            for (postSnapshot in dataSnapshot.children) {
                println(postSnapshot.child("title").value)
                //Here i can just get what ever variable i need with the line above.
            }
        }

        override fun onCancelled(databaseError: DatabaseError) {
            // Getting Post failed, log a message
            Log.w(TAG, "loadPost:onCancelled", databaseError.toException())
            // ...
        }
    })