How to collect a flow list value inside a relationship room database class and jetpack compose

Question

In my Android app I want to show only items that are within a group that the user touchs on using jetpack compose, room, kotlin coroutines and flow and update screen when add a new item for that group. I can create groups and associate items for each group with one-to-many relationship room database. I can also show all items from all groups. But I don't know how to show only the items in the group that the user touchs on and update the screen by collecting flow.

Group's Screen:

Group's Screen

When I touch on group1, I want to show only group1 items and when I add a new item on this group update screen automaticaly:

Items' Screen

Some codes...

Groups Entity:

@Entity
data class Groups(
    @PrimaryKey(autoGenerate = true)
    val groupId: Int,
    val groupName: String,
    //more code
)

Groups Dao:

@Dao
interface GroupsDao {
    @Query("SELECT * FROM Groups ORDER BY groupId ASC")
    fun getGroups(): Flow>

    @Transaction
    @Query("SELECT * FROM Groups")
    fun getGroupWithItens(): Flow>

    @Query("SELECT * FROM Groups WHERE groupId = :groupId")
    suspend fun getGroup(groupId: Int): Groups

    //more code
}

Items Entity:

@Entity
data class Itens(
    @PrimaryKey(autoGenerate = true)
    val itemId: Int,
    val groupOwnerId: Int,
    val itemName: String,
    //more code
)

Items Dao:

@Dao
interface ItensDao {
    @Query("SELECT * FROM 'Itens' ORDER BY itemId ASC")
    fun getItens(): Flow>

    @Query("SELECT * FROM 'Itens' WHERE itemId = :itemId")
    suspend fun getItem(itemId: Int): Itens

    //more code
}

Items ViewModel:

@HiltViewModel
class ItensViewModel @Inject constructor(
    private val repo: ItensRepository
) : ViewModel() {
    var item by mutableStateOf(Itens(0, 0, NO_VALUE, NO_VALUE))
        private set

    val itens = repo.getItens()

    fun getItem(itemId: Int) = viewModelScope.launch {
        item = repo.getItem(itemId)
    }

    //more code
}

Relationship data class GroupWithItens:

data class GroupWithItens(
    @Embedded val groups: Groups,
    @Relation(
        parentColumn = "groupId",
        entityColumn = "groupOwnerId"
    )
    val itens: List // THIS LIST I WANT DO COLLECT
)

GroupWithItens Dao:

@Dao
interface GroupWithItensDao {
    @Transaction
    @Query("SELECT * FROM Groups WHERE groupId = :groupId")
    fun getGroupWithItens(groupId: Int): Flow>
}

GroupWithItens Repository:

interface GroupWithItensRepository {
    fun getGroupWithItens(groupId: Int): Flow>
}

GroupWithItens RepositoryImpl:

class GroupWithItensRepositoryImpl(
    private val groupWithItensDao: GroupWithItensDao
) : GroupWithItensRepository {
    override fun getGroupWithItens(groupId: Int) = groupWithItensDao.getGroupWithItens(groupId)
}

GroupWithItens ViewModel:

@HiltViewModel
class GroupWithItensViewModel @Inject constructor(
    private val repo: GroupWithItensRepository
) : ViewModel() {

    var groupWithItens: Flow> = flow{GroupWithItens(Groups(0, "", "", LocalDateTime.now()), emptyList())}

    fun getGroupWithItens(groupId: Int) = viewModelScope.launch {
        groupWithItens = repo.getGroupWithItens(groupId)

        }
    }
}

ItensScreen:

@Composable
fun ItensScreen(
    viewModelItens: ItensViewModel = hiltViewModel(),
    viewModelGroups: GroupsViewModel = hiltViewModel(),
    viewModelGroupWithItens: GroupWithItensViewModel = hiltViewModel(),
    itemId: Int,
    groupId: Int,
    //more code
) {

    val itens by viewModelItens.itens.collectAsState(   //
        initial = emptyList()                           // THIS WORKS
    )                                                   //

    val groupWithItens by viewModelGroupWithItens.groupWithItens.collectAsState( //
        initial = 0                                                              // HERE I DON'T KNOW HOW TO GET JUST LIST
    )                                                                            //

    LaunchedEffect(Unit) {
        viewModelItens.getItem(itemId)
        viewModelGroups.getGroup(groupId)
        viewModelGroupWithItens.getGroupWithItens(groupId)
    }

    Log.d(
        "*****", "groupId: " + groupId
                + "
" + "itens: " + itens
                + "
" + "groupWithItens: " + groupWithItens
    )

    Scaffold(
        topBar = {
            //more code
        },
        bottomBar = {
           //more code
        },

        content = { padding ->
            ItensContent(
                padding = padding,
                itens = itens, //<- HERE SHOW ALL ITEMS
                deleteItem = { item ->
                    viewModelItens.deleteItem(item)
                }

         //more code
    )
}

Log output:

groupId: 1
itens: [Itens(itemId=1, groupOwnerId=1, itemName=item1_group1, itemDescription=), Itens(itemId=2, groupOwnerId=1, itemName=item2_group1, itemDescription=), Itens(itemId=4, groupOwnerId=2, itemName=item1_group2, itemDescription=)]
groupWithItens: [GroupWithItens(groups=Groups(groupId=1, groupName=group1, groupDescription=, groupDateCreation=2023-09-22T19:15:41.702022), itens=[Itens(itemId=1, groupOwnerId=1, itemName=item1_group1, itemDescription=), Itens(itemId=2, groupOwnerId=1, itemName=item2_group1, itemDescription=)])]

I want to collect just [Itens(itemId=1, groupOwnerId=1, itemName=item1_group1, itemDescription=), Itens(itemId=2, groupOwnerId=1, itemName=item2_group1, itemDescription=)])] part.

And composable cards:

@Composable
fun ItensContent(
    padding: PaddingValues,
    itens: List,
    deleteItem: (item: Itens) -> Unit,
) {
    LazyColumn(
        //more code
    ) {
        items(
            items = itens
        ) { item ->
            ItemCard(
                item = item,
                deleteItem = {
                    deleteItem(item)
                }
            )
        }
    }
}

@Composable
fun ItemCard(
    item: Itens,
    deleteItem: () -> Unit,
) {
    Card( 
        // more code
    ) {
        //more code
    }
}

So, how can I collect List in GroupWithItens data class with Kotlin Flow? I try things like: groupWithItens.itens or val itens by viewModelGroupWithItens.groupWithItens.collect( itens-> itens = itens ) but no success. I appreciate for your help!!

How to collect a flow list value inside a relationship room database class and jetpack compose

Answers (1)

Related Questions