Lab 04: add pagination

app/build.gradle.kts

@@ -76,6 +76,8 @@ dependencies {
     implementation("androidx.room:room-ktx:$room_version")
     implementation("androidx.room:room-paging:$room_version")
 
+    implementation("androidx.paging:paging-compose:3.2.1")
+
     //Tests
     testImplementation("junit:junit:4.13.2")
     androidTestImplementation("androidx.test.ext:junit:1.1.5")

app/src/main/java/com/example/mobile_labs/database/AppContainer.kt

@@ -29,5 +29,6 @@ class AppDataContainer(private val context: Context) : AppContainer {
 
     companion object {
         const val TIMEOUT = 5000L
+        const val LIMIT = 3
     }
 }

app/src/main/java/com/example/mobile_labs/database/event/dao/EventDao.kt

@@ -1,5 +1,6 @@
 package com.example.mobile_labs.database.event.dao
 
+import androidx.paging.PagingSource
 import androidx.room.Dao
 import androidx.room.Delete
 import androidx.room.Insert
@@ -9,14 +10,17 @@ import com.example.mobile_labs.database.event.model.Event
 import com.example.mobile_labs.database.event.model.EventWithPerformance
 import com.example.mobile_labs.database.performance.model.Performance
 import kotlinx.coroutines.flow.Flow
+import java.time.LocalDate
+import java.time.format.DateTimeFormatter
 
 @Dao
 interface EventDao {
     @Query("select * from events order by date asc")
     fun getAll(): Flow<List<Event>>
 
-    @Query("select * from events where events.date > :dateFrom order by date asc")
+    @Query("select * from events where events.date > :dateFrom order by date collate nocase asc")
-    fun getAllWithPerformance(dateFrom: String): Flow<List<EventWithPerformance>>
+    fun getAllWithPerformance(dateFrom: String? = LocalDate.now().format(
+        DateTimeFormatter.ofPattern("dd.MM"))): PagingSource<Int, EventWithPerformance>
 
     @Query("select * from events where events.uid = :uid")
     fun getByUid(uid: Int): Flow<EventWithPerformance>

app/src/main/java/com/example/mobile_labs/database/event/repository/EventRepository.kt

@@ -1,12 +1,13 @@
 package com.example.mobile_labs.database.event.repository
 
+import androidx.paging.PagingData
 import com.example.mobile_labs.database.event.model.Event
 import com.example.mobile_labs.database.event.model.EventWithPerformance
 import kotlinx.coroutines.flow.Flow
 
 interface EventRepository {
     fun getAll(): Flow<List<Event>>
-    fun getAllWithPerformance(): Flow<List<EventWithPerformance>>
+    fun getAllWithPerformance(): Flow<PagingData<EventWithPerformance>>
     fun getEvent(uid: Int): Flow<EventWithPerformance?>
     suspend fun insertEvent(event: Event)
     suspend fun updateEvent(event: Event)

app/src/main/java/com/example/mobile_labs/database/event/repository/OfflineEventRepository.kt

@@ -1,5 +1,9 @@
 package com.example.mobile_labs.database.event.repository
 
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.PagingData
+import com.example.mobile_labs.database.AppDataContainer
 import com.example.mobile_labs.database.event.dao.EventDao
 import com.example.mobile_labs.database.event.model.Event
 import com.example.mobile_labs.database.event.model.EventWithPerformance
@@ -9,9 +13,14 @@ import java.time.format.DateTimeFormatter
 
 class OfflineEventRepository(private val eventDao: EventDao) : EventRepository {
     override fun getAll(): Flow<List<Event>> = eventDao.getAll();
-    override fun getAllWithPerformance(): Flow<List<EventWithPerformance>> = eventDao.getAllWithPerformance(LocalDate.now().format(
+    override fun getAllWithPerformance(): Flow<PagingData<EventWithPerformance>> = Pager(
-        DateTimeFormatter.ofPattern("dd.MM")
+        config = PagingConfig(
-    ))
+            pageSize = AppDataContainer.LIMIT,
+            enablePlaceholders = false,
+        ),
+        pagingSourceFactory = eventDao::getAllWithPerformance
+    ).flow
+
     override fun getEvent(uid: Int): Flow<EventWithPerformance?> = eventDao.getByUid(uid);
 
     override suspend fun insertEvent(event: Event) = eventDao.insert(event);

app/src/main/java/com/example/mobile_labs/database/performance/dao/PerformanceDao.kt

@@ -1,5 +1,6 @@
 package com.example.mobile_labs.database.performance.dao
 
+import androidx.paging.PagingSource
 import androidx.room.Dao
 import androidx.room.Delete
 import androidx.room.Insert
@@ -13,7 +14,7 @@ import kotlinx.coroutines.flow.Flow
 @Dao
 interface PerformanceDao {
     @Query("select * from performances order by title collate nocase asc")
-    fun getAll(): Flow<List<Performance>>
+    fun getAll(): PagingSource<Int, Performance>
 
     @Query("select * from performances where performances.performance_uid = :uid")
     fun getByUid(uid: Int): Flow<PerformanceWithPeople>

app/src/main/java/com/example/mobile_labs/database/performance/repository/OfflinePerformanceRepository.kt

@@ -1,12 +1,22 @@
 package com.example.mobile_labs.database.performance.repository
 
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.PagingData
+import com.example.mobile_labs.database.AppDataContainer
 import com.example.mobile_labs.database.performance.dao.PerformanceDao
 import com.example.mobile_labs.database.performance.model.Performance
 import com.example.mobile_labs.database.performance.model.PerformanceWithPeople
 import kotlinx.coroutines.flow.Flow
 
 class OfflinePerformanceRepository(private val performanceDao: PerformanceDao) : PerformanceRepository {
-    override fun getAllPerformances(): Flow<List<Performance>> = performanceDao.getAll();
+    override fun getAllPerformances(): Flow<PagingData<Performance>> = Pager(
+        config = PagingConfig(
+            pageSize = AppDataContainer.LIMIT,
+            enablePlaceholders = false,
+        ),
+        pagingSourceFactory = performanceDao::getAll
+    ).flow
     override fun getPerformance(uid: Int): Flow<PerformanceWithPeople?> = performanceDao.getByUid(uid);
 
     override suspend fun insertPerformance(performance: Performance) = performanceDao.insert(performance);

app/src/main/java/com/example/mobile_labs/database/performance/repository/PerformanceRepository.kt

@@ -1,11 +1,12 @@
 package com.example.mobile_labs.database.performance.repository
 
+import androidx.paging.PagingData
 import com.example.mobile_labs.database.performance.model.Performance
 import com.example.mobile_labs.database.performance.model.PerformanceWithPeople
 import kotlinx.coroutines.flow.Flow
 
 interface PerformanceRepository {
-    fun getAllPerformances(): Flow<List<Performance>>
+    fun getAllPerformances(): Flow<PagingData<Performance>>
     fun getPerformance(uid: Int): Flow<PerformanceWithPeople?>
     suspend fun insertPerformance(performance: Performance)
     suspend fun updatePerformance(performance: Performance)

app/src/main/java/com/example/mobile_labs/database/person/dao/PersonDao.kt

@@ -1,5 +1,6 @@
 package com.example.mobile_labs.database.person.dao
 
+import androidx.paging.PagingSource
 import androidx.room.Dao
 import androidx.room.Delete
 import androidx.room.Insert
@@ -11,7 +12,7 @@ import kotlinx.coroutines.flow.Flow
 @Dao
 interface PersonDao {
     @Query("select * from people order by last_name collate nocase asc")
-    fun getAll(): Flow<List<Person>>
+    fun getAll(): PagingSource<Int, Person>
 
     @Query("select * from people where people.uid = :uid")
     fun getByUid(uid: Int): Flow<Person>

app/src/main/java/com/example/mobile_labs/database/person/repository/OfflinePersonRepository.kt

@@ -1,11 +1,22 @@
 package com.example.mobile_labs.database.person.repository
 
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.PagingData
+import com.example.mobile_labs.database.AppContainer
+import com.example.mobile_labs.database.AppDataContainer
 import com.example.mobile_labs.database.person.dao.PersonDao
 import com.example.mobile_labs.database.person.model.Person
 import kotlinx.coroutines.flow.Flow
 
 class OfflinePersonRepository(private val personDao: PersonDao) : PersonRepository {
-    override fun getAllPeople(): Flow<List<Person>> = personDao.getAll();
+    override fun getAllPeople(): Flow<PagingData<Person>> = Pager(
+        config = PagingConfig(
+            pageSize = AppDataContainer.LIMIT,
+            enablePlaceholders = false,
+        ),
+        pagingSourceFactory = personDao::getAll
+    ).flow;
     override fun getPerson(uid: Int): Flow<Person?> = personDao.getByUid(uid);
 
     override suspend fun insertPerson(person: Person) = personDao.insert(person);

app/src/main/java/com/example/mobile_labs/database/person/repository/PersonRepository.kt

@@ -1,10 +1,11 @@
 package com.example.mobile_labs.database.person.repository
 
+import androidx.paging.PagingData
 import com.example.mobile_labs.database.person.model.Person
 import kotlinx.coroutines.flow.Flow
 
 interface PersonRepository {
-    fun getAllPeople(): Flow<List<Person>>
+    fun getAllPeople(): Flow<PagingData<Person>>
     fun getPerson(uid: Int): Flow<Person?>
     suspend fun insertPerson(person: Person)
     suspend fun updatePerson(person: Person)

app/src/main/java/com/example/mobile_labs/ui/event/list/EventList.kt

@@ -35,17 +35,24 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavController
+import androidx.paging.PagingData
+import androidx.paging.compose.LazyPagingItems
+import androidx.paging.compose.collectAsLazyPagingItems
+import androidx.paging.compose.itemContentType
+import androidx.paging.compose.itemKey
 import coil.compose.AsyncImage
 import com.example.mobile_labs.R
 import com.example.mobile_labs.database.AppDatabase
 import com.example.mobile_labs.database.event.model.Event
 import com.example.mobile_labs.database.event.model.EventWithPerformance
+import com.example.mobile_labs.database.performance.model.Performance
 import com.example.mobile_labs.database.person.model.Person
 import com.example.mobile_labs.ui.AppViewModelProvider
 import com.example.mobile_labs.ui.navigation.Screen
 import com.example.mobile_labs.ui.person.list.PeopleListViewModel
 import com.example.mobile_labs.ui.theme.Mobile_LabsTheme
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.withContext
 import java.time.LocalDate
 import java.time.format.DateTimeFormatter
@@ -55,14 +62,14 @@ fun EventList(
     navController: NavController,
     viewModel: EventListViewModel = viewModel(factory = AppViewModelProvider.Factory)
 ) {
-    val eventListUiState by viewModel.eventListUiState.collectAsState()
+    val eventListUiState = viewModel.eventListUiState.collectAsLazyPagingItems()
 
     Column(
         horizontalAlignment = Alignment.CenterHorizontally,
         modifier = Modifier
             .padding(all = 10.dp)) {
         EventList(
-            eventList = eventListUiState.eventList,
+            eventList = eventListUiState,
             onClick = {uid : Int ->
                 val route = Screen.PerformanceView.route.replace("{id}", uid.toString())
                 navController.navigate(route)
@@ -75,13 +82,13 @@ fun EventList(
 @Composable
 private fun EventList(
     modifier: Modifier = Modifier,
-    eventList: List<EventWithPerformance>,
+    eventList: LazyPagingItems<EventWithPerformance>,
     onClick: (uid: Int) -> Unit
 ) {
     Column(
         modifier = modifier
     ) {
-        if (eventList.isEmpty()) {
+        if (eventList.itemCount == 0) {
             Text(
                 text = stringResource(R.string.events_missing_description),
                 textAlign = TextAlign.Center,
@@ -89,7 +96,13 @@ private fun EventList(
             )
         } else {
             LazyColumn(modifier = Modifier.padding(all = 10.dp)) {
-                items(items = eventList, key = { it.event.uid !! }) { event ->
+                items(
+                    count = eventList.itemCount,
+                    key = eventList.itemKey(),
+                    contentType = eventList.itemContentType(),
+                ) { index ->
+                    val event = eventList[index]
+                    event?.let{
                         EventListItem(event = event, modifier = Modifier
                             .padding(vertical = 7.dp), onClick = onClick)
                     }
@@ -97,6 +110,7 @@ private fun EventList(
             }
         }
     }
+}
 
 @Composable
 private fun EventListItem(
@@ -133,7 +147,10 @@ fun SchedulePreview() {
         Surface(
             color = MaterialTheme.colorScheme.background
         ) {
-            EventList(eventList = listOf(), onClick = {})
+            EventList(eventList = MutableStateFlow(
+                PagingData.empty<EventWithPerformance>()
+            ).collectAsLazyPagingItems(),
+                onClick = {})
         }
     }
 }

app/src/main/java/com/example/mobile_labs/ui/event/list/EventListViewModel.kt

@@ -2,10 +2,12 @@ package com.example.mobile_labs.ui.event.list
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.paging.PagingData
 import com.example.mobile_labs.database.AppDataContainer
 import com.example.mobile_labs.database.event.repository.EventRepository
 import com.example.mobile_labs.database.event.model.Event
 import com.example.mobile_labs.database.event.model.EventWithPerformance
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.map
@@ -14,13 +16,5 @@ import kotlinx.coroutines.flow.stateIn
 class EventListViewModel(
     private val eventRepository: EventRepository
 ) : ViewModel() {
-    val eventListUiState: StateFlow<EventListUiState> = eventRepository.getAllWithPerformance().map {
+    val eventListUiState: Flow<PagingData<EventWithPerformance>> = eventRepository.getAllWithPerformance()
-        EventListUiState(it)
-    }.stateIn(
-        scope = viewModelScope,
-        started = SharingStarted.WhileSubscribed(stopTimeoutMillis = AppDataContainer.TIMEOUT),
-        initialValue = EventListUiState()
-    )
 }
-
-data class EventListUiState(val eventList: List<EventWithPerformance> = listOf())

app/src/main/java/com/example/mobile_labs/ui/performance/list/PerformanceList.kt

@@ -36,6 +36,11 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavController
+import androidx.paging.PagingData
+import androidx.paging.compose.LazyPagingItems
+import androidx.paging.compose.collectAsLazyPagingItems
+import androidx.paging.compose.itemContentType
+import androidx.paging.compose.itemKey
 import coil.compose.AsyncImage
 import com.example.mobile_labs.R
 import com.example.mobile_labs.database.AppDatabase
@@ -45,9 +50,11 @@ import com.example.mobile_labs.database.performance.model.Performance
 import com.example.mobile_labs.database.person.model.Person
 import com.example.mobile_labs.ui.AppViewModelProvider
 import com.example.mobile_labs.ui.navigation.Screen
+import com.example.mobile_labs.ui.person.list.PeopleList
 import com.example.mobile_labs.ui.person.list.PeopleListViewModel
 import com.example.mobile_labs.ui.theme.Mobile_LabsTheme
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.withContext
 import java.time.LocalDate
 import java.time.format.DateTimeFormatter
@@ -57,14 +64,14 @@ fun PerformanceList(
     navController: NavController,
     viewModel: PerformanceListViewModel = viewModel(factory = AppViewModelProvider.Factory)
 ) {
-    val performanceListUiState by viewModel.performanceListUiState.collectAsState()
+    val performanceListUiState = viewModel.performanceListUiState.collectAsLazyPagingItems()
 
     Column(
         horizontalAlignment = Alignment.CenterHorizontally,
         modifier = Modifier
             .padding(all = 10.dp)) {
         PerformanceList(
-            performanceList = performanceListUiState.performanceList,
+            performanceList = performanceListUiState,
             onClick = {uid : Int ->
                 val route = Screen.PerformanceView.route.replace("{id}", uid.toString())
                 navController.navigate(route)
@@ -77,13 +84,13 @@ fun PerformanceList(
 @Composable
 private fun PerformanceList(
     modifier: Modifier = Modifier,
-    performanceList: List<Performance>,
+    performanceList: LazyPagingItems<Performance>,
     onClick: (uid: Int) -> Unit
 ) {
     Column(
         modifier = modifier
     ) {
-        if (performanceList.isEmpty()) {
+        if (performanceList.itemCount == 0) {
             Text(
                 text = stringResource(R.string.performance_missing_description),
                 textAlign = TextAlign.Center,
@@ -91,7 +98,13 @@ private fun PerformanceList(
             )
         } else {
             LazyColumn(modifier = Modifier.padding(all = 10.dp)) {
-                items(items = performanceList, key = { it.performance_uid !! }) { performance ->
+                items(
+                    count = performanceList.itemCount,
+                    key = performanceList.itemKey(),
+                    contentType = performanceList.itemContentType()
+                ) { index ->
+                    val performance = performanceList[index]
+                    performance?.let {
                         PerformanceListItem(performance = performance, modifier = Modifier
                             .padding(vertical = 7.dp), onClick = onClick)
                     }
@@ -99,6 +112,7 @@ private fun PerformanceList(
             }
         }
     }
+}
 
 @Composable
 private fun PerformanceListItem(
@@ -132,7 +146,12 @@ fun SchedulePreview() {
         Surface(
             color = MaterialTheme.colorScheme.background
         ) {
-            PerformanceList(performanceList = listOf(), onClick = {})
+            PerformanceList(
+                performanceList = MutableStateFlow(
+                    PagingData.empty<Performance>()
+                ).collectAsLazyPagingItems(),
+                onClick = {}
+            )
         }
     }
 }

app/src/main/java/com/example/mobile_labs/ui/performance/list/PerformanceListViewModel.kt

@@ -2,9 +2,12 @@ package com.example.mobile_labs.ui.performance.list
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.paging.PagingData
 import com.example.mobile_labs.database.AppDataContainer
 import com.example.mobile_labs.database.performance.model.Performance
 import com.example.mobile_labs.database.performance.repository.PerformanceRepository
+import com.example.mobile_labs.database.person.model.Person
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.map
@@ -13,17 +16,5 @@ import kotlinx.coroutines.flow.stateIn
 class PerformanceListViewModel(
     private val performanceRepository: PerformanceRepository
 ) : ViewModel() {
-    val performanceListUiState: StateFlow<PerformanceListUiState> = performanceRepository.getAllPerformances().map {
+    val performanceListUiState: Flow<PagingData<Performance>> = performanceRepository.getAllPerformances()
-        PerformanceListUiState(it)
-    }.stateIn(
-        scope = viewModelScope,
-        started = SharingStarted.WhileSubscribed(stopTimeoutMillis = AppDataContainer.TIMEOUT),
-        initialValue = PerformanceListUiState()
-    )
-
-//    suspend fun deleteStudent(student: Student) {
-//        studentRepository.deleteStudent(student)
-//    }
 }
-
-data class PerformanceListUiState(val performanceList: List<Performance> = listOf())

app/src/main/java/com/example/mobile_labs/ui/person/list/PeopleList.kt

@@ -41,6 +41,11 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavController
+import androidx.paging.PagingData
+import androidx.paging.compose.LazyPagingItems
+import androidx.paging.compose.collectAsLazyPagingItems
+import androidx.paging.compose.itemContentType
+import androidx.paging.compose.itemKey
 import coil.compose.AsyncImage
 import com.example.mobile_labs.R
 import com.example.mobile_labs.ui.navigation.Screen
@@ -50,6 +55,7 @@ import com.example.mobile_labs.database.person.model.Person
 import com.example.mobile_labs.ui.AppViewModelProvider
 import com.example.mobile_labs.ui.theme.Mobile_LabsTheme
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.withContext
 import java.time.LocalDate
 import java.time.format.DateTimeFormatter
@@ -58,7 +64,7 @@ import java.time.format.DateTimeFormatter
 fun PeopleList(
     viewModel: PeopleListViewModel = viewModel(factory = AppViewModelProvider.Factory)
 ) {
-    val peopleListUiState by viewModel.personListUiState.collectAsState()
+    val peopleListUiState = viewModel.personListUiState.collectAsLazyPagingItems()
 
     Column(
         horizontalAlignment = Alignment.CenterHorizontally,
@@ -67,7 +73,7 @@ fun PeopleList(
         PeopleList(
             modifier = Modifier
                 .fillMaxSize(),
-            peopleList = peopleListUiState.personList
+            peopleList = peopleListUiState
         )
     }
 }
@@ -76,12 +82,12 @@ fun PeopleList(
 @Composable
 private fun PeopleList(
     modifier: Modifier = Modifier,
-    peopleList: List<Person>,
+    peopleList: LazyPagingItems<Person>,
 ) {
     Column(
         modifier = modifier
     ) {
-        if (peopleList.isEmpty()) {
+        if (peopleList.itemCount == 0) {
             Text(
                 text = stringResource(R.string.people_missing_description),
                 textAlign = TextAlign.Center,
@@ -89,9 +95,15 @@ private fun PeopleList(
             )
         } else {
             LazyColumn(modifier = Modifier.padding(all = 10.dp)) {
-                items(items = peopleList, key = { it.uid !! }) { person ->
+                items(
-                    PeopleListItem(person = person, modifier = Modifier
+                    count = peopleList.itemCount,
-                        .padding(vertical = 7.dp))
+                    key = peopleList.itemKey(),
+                    contentType = peopleList.itemContentType()
+                ) { index ->
+                    val person = peopleList[index]
+                    person?.let {
+                        PeopleListItem(person = person, modifier = Modifier.padding(10.dp))
+                    }
                 }
             }
         }
@@ -130,7 +142,9 @@ fun PeopleListPreview() {
         Surface(
             color = MaterialTheme.colorScheme.background
         ) {
-            PeopleList(peopleList = listOf())
+            PeopleList(peopleList = MutableStateFlow(
+                PagingData.empty<Person>()
+            ).collectAsLazyPagingItems())
         }
     }
 }

app/src/main/java/com/example/mobile_labs/ui/person/list/PeopleListViewModel.kt

@@ -2,9 +2,11 @@ package com.example.mobile_labs.ui.person.list
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.paging.PagingData
 import com.example.mobile_labs.database.AppDataContainer
 import com.example.mobile_labs.database.person.model.Person
 import com.example.mobile_labs.database.person.repository.PersonRepository
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.map
@@ -13,13 +15,5 @@ import kotlinx.coroutines.flow.stateIn
 class PeopleListViewModel(
     private val personRepository: PersonRepository
 ) : ViewModel() {
-    val personListUiState: StateFlow<PersonListUiState> = personRepository.getAllPeople().map {
+    val personListUiState: Flow<PagingData<Person>> = personRepository.getAllPeople()
-        PersonListUiState(it)
-    }.stateIn(
-        scope = viewModelScope,
-        started = SharingStarted.WhileSubscribed(stopTimeoutMillis = AppDataContainer.TIMEOUT),
-        initialValue = PersonListUiState()
-    )
 }
-
-data class PersonListUiState(val personList: List<Person> = listOf())