Recycler View not loading data when retrieved from cloud firestore

Question

I have a RecyclerView, my adapter class works when the data is added to myModel objects from an array of string resources and floats, but not when these strings are retrieved from firestore. I have done this with textViews in other parts of my application fine. At first I tried using toObject<Model>() to populate the list passed to my adapter and now I have manually got the data from the hashMap. I have used snackbars to ensure the data is in the list that is passed to my adapter. I have tried overriding the onStart() and onstop() to listen for changes to the database but mAdapter is a local variable in oncreate() and it is not important that the data in this recycler view updates in realtime, updating when the activity launches is plenty.

This doesn't work:

collection.get().addOnSuccessListener { querySnapshot ->
        for (i in 0 until querySnapshot.size()){

            val data = querySnapshot.documents[i].data
            val Model = Model()

            val name = data!!["Name"].toString()
            val rating = data!!["Rating"].toString().toFloat()
            Model.Name= name
            Model.Rating = rating




            list.add(Model)

This does:

    val myImageNameList = arrayOf(R.string.1, R.string.2, R.string.cafe_3, R.string.4, R.string.5, R.string.6, R.string.7, R.8)
    val myImageRatingList = arrayOf(2.4f, 4.1f, 3.6f, 3.4f, 2.8f, 1.9f, 4.1f, 3.9f )

    for (i in 0..7){
        val model = Model()
        model.Name = getString(myImageNameList[i])
        model.Rating = myImageRatingList[i]
        list.add(model)
    }

Adapter class excerpt:

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Adapter.ViewHolder {
    val inflater = LayoutInflater.from(parent.context)
    val v = inflater.inflate(R.layout.row_layout, parent, false)

    return ViewHolder(v)
}

//bind the data to child views of the ViewHolder
override fun onBindViewHolder(holder: Adapter.ViewHolder, position: Int) {
    val info = imageModelArrayList[position]

    
    holder.txtMsg.text = info.Name
    holder.ratingbar.rating = info.Rating
    holder.ratingDecimal.text = "("+ info.Rating + ")"
}

//get the max size of the recycler view
override fun getItemCount(): Int {
    return imageModelArrayList.size
}

inner class ViewHolder(itemView: View):RecyclerView.ViewHolder(itemView), View.OnClickListener{
    var txtMsg = itemView.findViewById<View>(R.id.firstLine) as TextView
    var ratingbar = itemView.findViewById<View>(R.id.rating) as RatingBar

I am confused why the second way of creating model objects works but the first does not, as far as I know in both instances I am creating a model object and assigning its fields with a string and afloat, just in the first example the string and float happen to have come from the firestorm.

edit

the list is passed when instantiating myAdapter as param imageModelArrayList

      val recyclerView = findViewById<View>(R.id.recycler_view) as RecyclerView
    val layoutManager = LinearLayoutManager(this)

    recyclerView.layoutManager = layoutManager


    val imageModelArrayList = populateList()
    val mAdapter = Adapter(imageModelArrayList)
    recyclerView.adapter = mAdapter

In your first code snippet, how do you use the created `list`. Can you add that code in the question as well? — Arpit Shukla, Dec 06 '21 at 03:20
@ArpitShukla list is passed to myAdapter as param ImageModelArrayList edited question to clarify — Bennettleben, Dec 06 '21 at 03:28
Are `list` (in list.add(Model)) and `imageModelArrayList` same? — Arpit Shukla, Dec 06 '21 at 03:30
You need to update your recycler view when you receive response from firestore i.e. inside addOnSuccessListener. Does your `populateList` function have anything other than what you pasted in the 1st snippet? — Arpit Shukla, Dec 06 '21 at 03:36
@ArpitShukla populate list only contains the first snippet, plus a few val declarations for list, db, mainView and collection. it then returns the list — Bennettleben, Dec 06 '21 at 03:39
Passing the recyclerView as a param into populate list and creating the adapter there worked, thankyou — Bennettleben, Dec 06 '21 at 03:45
@ArpitShukla is there a better way? I'm having trouble using the second answer here: https://stackoverflow.com/questions/30398247/how-to-filter-a-recyclerview-with-a-searchview to search through my list using a custom app bar using this method — Bennettleben, Dec 06 '21 at 07:11

score 0 · Answer 1 · answered Dec 06 '21 at 03:58

Passed the recyclerView into the method where my data is gathered, and created the adapter inside my addOnSuccessListener

 val data = querySnapshot.documents[i]
            val model = Model()

            val name = data!!["Name"].toString()
            val rating = data!!["Rating"].toString().toFloat()
            model.Name= name
            model.Rating = rating


            
            list.add(model)
            


        }
  
        val mAdapter = Adapter(list)
        recyclerView.adapter = mAdapter
    }

Recycler View not loading data when retrieved from cloud firestore

1 Answers1