midrissi / cinema_news

Android sample code for Jetpack Paging3 Library

cinema_news

This repository is all about Paging3 implementation for various use cases like

• Paging using network (retrofit) as data source
• Paging using network and local db room.
• Showing footer error view or loading states.

CAN you explain with code? OK :

showMediator:

@ExperimentalPagingApi class ShowMediator(val showApiService: ShowApiService, val appDatabase: AppDatabase, var show_searcch_key: String ) :RemoteMediator<Int, Search>() {

override suspend fun load(
    loadType: LoadType, state: PagingState<Int, Search>
): MediatorResult {


    try {
        val pageKeyData = getKeyPageData(loadType, state)
        val page = when (pageKeyData) {
            is MediatorResult.Success -> {
                return pageKeyData
            }
            else -> {
                pageKeyData as Int
            }
        }
        val response = showApiService
            .getShowImages(page, state.config.pageSize, show_searcch_key)




        var response_search= response.Search
        val isEndOfList = response_search.isEmpty()
        appDatabase.withTransaction {
            // clear all tables in the database
            if (loadType == LoadType.REFRESH) {
                appDatabase.getRepoDao().clearRemoteKeys()
                appDatabase.getShowsDao().clearAllDoggos()
            }
            val prevKey = if(page.equals(DEFAULT_PAGE_INDEX)) null else page - 1
            val nextKey = if (isEndOfList) null else page + 1
            val keys = response_search.map {
                RemoteKeys(repoId = it.imdbID, prevKey = prevKey, nextKey = nextKey)
            }
            appDatabase.getRepoDao().insertAll(keys)
            appDatabase.getShowsDao().insertAll(response_search)
        }
        return MediatorResult.Success(endOfPaginationReached = isEndOfList)
    } catch (exception: IOException) {
        return MediatorResult.Error(exception)
    } catch (exception: HttpException) {
        return MediatorResult.Error(exception)
    }
}

[showImagesRepository](app/src/main/java/com/taghda/cinema_news/repo/paging/ShowImagesRepository.kt) : 

    override fun letDoggoImagesFlowDb(pagingConfig: PagingConfig, show_searcch_key: String): Flow<PagingData<Search>> {


    val pagingSourceFactory = { appDatabase.getShowsDao().getAllShowModel() }
        val dm = ShowMediator(showApiService, appDatabase, show_searcch_key)


        return Pager(
            config = pagingConfig,
            pagingSourceFactory = pagingSourceFactory,
            remoteMediator = dm
        ).flow

}

RoomViewModel :

class RoomViewModel @ViewModelInject constructor( val repository: ShowImagesRepo ) : ViewModel() { var searched_key: String= "russia"

fun fetchShowsImages(): Flow<PagingData<Search>> {
   return repository.letDoggoImagesFlowDb(
       repository.getDefaultPageConfig(), searched_key).cachedIn(viewModelScope)
    }

RoomShowImageAdapter:

class RoomShowImageAdapter : PagingDataAdapter<Search, RoomShowImageAdapter.ShowsImageViewHolder>(REPO_COMPARATOR) {

RoomFragment :

private fun fetchDoggoImages() {
    lifecycleScope.launch {
        roomViewModel.fetchShowsImages().distinctUntilChanged().collectLatest {
            adapter.submitData(it)
        }
    }
}


private fun initMembers() {
//    roomViewModel = defaultViewModelProviderFactory.create(RoomViewModel::class.java)
    adapter = RoomShowImageAdapter()
    loaderStateAdapter = LoaderStateAdapter { adapter.retry() }
}


private fun setUpViews(view: View) {
    recyclerView = view.findViewById(R.id.rvDoggoRoom)
    searchEditText = view.findViewById(R.id.input)
    recyclerView.layoutManager = LinearLayoutManager(context)
    recyclerView.adapter = adapter.withLoadStateFooter(loaderStateAdapter)
}

}

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