Dao class
@Dao
interface ShlokaDao {
@Query("SELECT * FROM shlokas_table ORDER BY _Id ASC LIMIT :limit OFFSET :offset ")
suspend fun getPagedShlokasList(limit: Int, offset: Int): List<Shloka>
}
Paging DataSource
class ShlokasDataSource(private val shlokasRepository: ShlokasRepository): PagingSource<Int, Shloka>() {
override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Shloka> {
val page = params.key ?: 0
return try {
Log.d("MainPagingSource", "load: $page")
val entities = shlokasRepository.getPagedShlokasList( params.loadSize, page * params.loadSize)
if (page != 0) delay(1000)
LoadResult.Page(
data = entities,
prevKey = if (page == 0) null else page - 1,
nextKey = if (entities.isEmpty()) null else page + 1
)
} catch (e: Exception) {
LoadResult.Error(e)
}
}
override fun getRefreshKey(state: PagingState<Int, Shloka>): Int? {
return state.anchorPosition?.let { anchorPosition ->
val anchorPage = state.closestPageToPosition(anchorPosition)
anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
}
}
}
ViewModel class
class ShlokasViewModel(private val shlokasRepository: ShlokasRepository): ViewModel() {
val data: Flow<PagingData<Shloka>> = Pager(
PagingConfig(
pageSize = 20,
enablePlaceholders = false,
)
) {
ShlokasDataSource(shlokasRepository)
}.flow.cachedIn(viewModelScope)
}
ShlokasScreen
@Composable
fun ShlokasScreen(
canNavigateBack: Boolean,
navigateUp: () -> Unit,
onSearchBtnClick: () -> Unit,
onShlokasClick: (Int) -> Unit,
viewModel: ShlokasViewModel = viewModel(factory = AppViewModelProvider.Factory)
) {
val shlokasData = viewModel.data.collectAsLazyPagingItems()
Scaffold(
contentPadding = PaddingValues(16.dp),
topBar = {
ShlokasAppBar(
canNavigateBack = canNavigateBack,
navigateUp = navigateUp,
onSearchClicked = onSearchBtnClick
)
}
) { innerPadding ->
LazyColumn(
modifier = Modifier.fillMaxSize(),
contentPadding = innerPadding
) {
items(
items = shlokasData.itemSnapshotList,
key = { it!!._Id }
) {shlokas->
shlokas?.let {
ShlokaCard(
shloka = shlokas,
onClick = { onShlokasClick(it._Id)
}
)
}
shlokasData.apply {
when (loadState.append) {
is LoadState.NotLoading -> Unit
LoadState.Loading -> {
LoadingItem()
}
is LoadState.Error -> {
ErrorItem(message = "Some error occurred")
}
}
when (loadState.refresh) {
is LoadState.NotLoading -> Unit
LoadState.Loading -> {
Box(
modifier = Modifier.fillMaxSize(),
contentAlignment = Center
) {
CircularProgressIndicator()
}
}
is LoadState.Error -> TODO()
}
}
}
}
}
}
i have more than 80+ words in pre-populated room database but it is only showing 60 words in 0th page.I tried to load data from pre-populated database but it is not paginating data as expected.
I followed this tutorials https://www.simplifiedcoding.net/pagination-in-jetpack-compose/ https://genicsblog.com/gouravkhunger/pagination-in-android-room-database-using-the-paging-3-library
