FirestorePagingAdapter setSnapshotArray

[VincentJoshuaET]

Currently, I am using FirestoreRecyclerAdapter on my RecyclerViews to save their scroll positions upon fragment destroy (I use Android Jetpack Navigation Components).

This is how I do it: https://proandroiddev.com/fui-rv-state-a66833c3bb88

I want to switch to FirestorePagingAdapter to improve the performance of my app, but it seems that I cannot save my recyclerview's scroll positions because FirestorePagingAdapter always queries for the data upon start.

[VincentJoshuaET]

Update: I did manage to use modify FirestorePagingAdapter and FirestorePagingOptions to use the existing LiveData from my ViewModel:

ViewModel:

private val config =
    PagedList.Config.Builder()
        .setEnablePlaceholders(false)
        .setPrefetchDistance(2)
        .setPageSize(2)
        .build()
private val factoryPetShop = FirestoreDataSource.Factory(firestoreRepo.getPets(), Source.DEFAULT)
val liveDataPetShop = LivePagedListBuilder(factoryPetShop, config).build()

FirestorePagingOptions:

fun build(data : LiveData<PagedList<DocumentSnapshot>>, modelClass: Class<T>): FirestorePagingOptions<T> {
    val parser = ClassSnapshotParser(modelClass)
    return FirestorePagingOptions(data, ClassSnapshotParser(modelClass), DefaultSnapshotDiffCallback(parser), mOwner)
}

I know this can be better, but this is just what I need for my app. But still, hoping this feature can be added.

[im-not-alex]

Update: I did manage to use modify FirestorePagingAdapter and FirestorePagingOptions to use the existing LiveData from my ViewModel:

ViewModel:

private val config =
    PagedList.Config.Builder()
        .setEnablePlaceholders(false)
        .setPrefetchDistance(2)
        .setPageSize(2)
        .build()
private val factoryPetShop = FirestoreDataSource.Factory(firestoreRepo.getPets(), Source.DEFAULT)
val liveDataPetShop = LivePagedListBuilder(factoryPetShop, config).build()

FirestorePagingOptions:

fun build(data : LiveData<PagedList<DocumentSnapshot>>, modelClass: Class<T>): FirestorePagingOptions<T> {
    val parser = ClassSnapshotParser(modelClass)
    return FirestorePagingOptions(data, ClassSnapshotParser(modelClass), DefaultSnapshotDiffCallback(parser), mOwner)
}

I know this can be better, but this is just what I need for my app. But still, hoping this feature can be added.

How did you extend FirestorePagingOptions if it is final? did you fetch and modified it? If yes how do you rebuild it to be a library into a project?
Thanks

[VincentJoshuaET]

Update: I did manage to use modify FirestorePagingAdapter and FirestorePagingOptions to use the existing LiveData from my ViewModel:

ViewModel:

private val config =
    PagedList.Config.Builder()
        .setEnablePlaceholders(false)
        .setPrefetchDistance(2)
        .setPageSize(2)
        .build()
private val factoryPetShop = FirestoreDataSource.Factory(firestoreRepo.getPets(), Source.DEFAULT)
val liveDataPetShop = LivePagedListBuilder(factoryPetShop, config).build()

FirestorePagingOptions:

fun build(data : LiveData<PagedList<DocumentSnapshot>>, modelClass: Class<T>): FirestorePagingOptions<T> {
    val parser = ClassSnapshotParser(modelClass)
    return FirestorePagingOptions(data, ClassSnapshotParser(modelClass), DefaultSnapshotDiffCallback(parser), mOwner)
}

I know this can be better, but this is just what I need for my app. But still, hoping this feature can be added.

How did you extend FirestorePagingOptions if it is final? did you fetch and modified it? If yes how do you rebuild it to be a library into a project?
Thanks

Yep. Just copied the whole files into my project. I didn't rebuilt the libraries.

[mandelmech]

Does this also solve the fact that the adapter re-fetches the data every time you leave and come back? I'm having tremendous trouble fixing this. Whenever I click an item and come back to the list, the query is re-run, same with orientation changes.

[VincentJoshuaET]

Does this also solve the fact that the adapter re-fetches the data every time you leave and come back? I'm having tremendous trouble fixing this. Whenever I click an item and come back to the list, the query is re-run, same with orientation changes.

It does it for me. The data set is saved and scroll position is restored.

[mandelmech]

I see you use a FirestoreDataSource and pagedlist, can you share how you query to make the datasource work? Thanks!