Пагинация, стагнация, ампутация, цивилизация, синхронизация, фракция, грация, конкатанация, нация, рация, сублимация, аннотация, субстанция

app/build.gradle

@@ -83,4 +83,8 @@ dependencies {
     implementation("androidx.hilt:hilt-navigation-compose:1.0.0")
     implementation 'androidx.compose.runtime:runtime-livedata:1.0.0-beta01'
     implementation "androidx.datastore:datastore-preferences:1.0.0"
+
+
+    implementation("androidx.room:room-paging:2.5.0")
+    implementation("androidx.paging:paging-compose:3.2.1")
 }

app/src/main/java/com/example/shawarma/data/interfaces/dao/ProductDao.kt

@@ -1,5 +1,6 @@
 package com.example.shawarma.data.interfaces.dao
 
+import androidx.paging.PagingSource
 import androidx.room.Dao
 import androidx.room.Delete
 import androidx.room.Insert
@@ -30,4 +31,12 @@ interface ProductDao {
     @Query("select * from products where products.id = :id")
     fun getById(id: Int): Flow<ProductModel>
 
+    @Query("select * from products where products.product_old_price is null")
+    fun getPaged(): PagingSource<Int, ProductModel>
+
+    @Query("select * from products where products.product_old_price is not null")
+    fun getPagedDiscounts(): PagingSource<Int, ProductModel>
+
+    @Query("select * from products")
+    fun getPagedItems(): PagingSource<Int, ProductModel>
 }

app/src/main/java/com/example/shawarma/data/repos/ProductRepository.kt

@@ -1,5 +1,8 @@
 package com.example.shawarma.data.repos
 
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.PagingData
 import com.example.shawarma.data.interfaces.dao.OrderProductDao
 import com.example.shawarma.data.interfaces.dao.ProductDao
 import com.example.shawarma.data.models.ProductModel
@@ -20,7 +23,7 @@ class ProductRepository @Inject constructor(
         orderProductDao.deleteByProductId(product.id!!)
         return productDao.delete(product)
     }
-    fun getAll(): Flow<List<ProductModel>> {
+    /*fun getAll(): Flow<List<ProductModel>> {
         return productDao.getAll()
     }
     fun getDiscounts(): Flow<List<ProductModel>> {
@@ -28,8 +31,32 @@ class ProductRepository @Inject constructor(
     }
     fun getItems(): Flow<List<ProductModel>> {
         return productDao.getItems()
-    }
+    }*/
     fun getById(id: Int): Flow<ProductModel> {
         return productDao.getById(id)
     }
+    fun getAllProductsPaged(): Flow<PagingData<ProductModel>> = Pager(
+        config = PagingConfig(
+            pageSize = 6,
+            enablePlaceholders = false
+        ),
+        pagingSourceFactory = productDao::getPaged
+    ).flow
+
+    fun getAllDiscountsPaged(): Flow<PagingData<ProductModel>> = Pager(
+        config = PagingConfig(
+            pageSize = 6,
+            enablePlaceholders = false
+        ),
+        pagingSourceFactory = productDao::getPagedDiscounts
+    ).flow
+
+    fun getAllItemsPaged(): Flow<PagingData<ProductModel>> = Pager(
+        config = PagingConfig(
+            pageSize = 6,
+            enablePlaceholders = false
+        ),
+        pagingSourceFactory = productDao::getPagedItems
+    ).flow
+
 }

app/src/main/java/com/example/shawarma/screens/discount/DiscountScreen.kt

@@ -20,7 +20,6 @@ import androidx.compose.material.ButtonDefaults
 import androidx.compose.material.Card
 import androidx.compose.material.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -33,6 +32,7 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import androidx.compose.ui.zIndex
 import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.paging.compose.collectAsLazyPagingItems
 import com.example.shawarma.R
 import com.example.shawarma.data.models.ProductModel
 import com.example.shawarma.data.sharedpref.PreferencesManager
@@ -60,7 +60,7 @@ fun DiscountScreen() {
 fun DiscountList(){
     val homeViewModel: HomeViewModel = hiltViewModel<HomeViewModel>()
 
-    val products = homeViewModel.discounts.observeAsState().value
+    val productsListUiState = homeViewModel.discountListUiState.collectAsLazyPagingItems()
 
     Box(
         modifier = Modifier
@@ -83,33 +83,31 @@ fun DiscountList(){
             modifier = Modifier.padding(top = 80.dp)
         )
         {
-            if (products != null) {
+            items(productsListUiState.itemCount) { index ->
-                items(products.size) { index ->
+                if (index % 2 == 0 && index == productsListUiState.itemCount - 1) {
-                    if (index % 2 == 0 && index == products.size - 1) {
+                    Row(
+                        horizontalArrangement = Arrangement.SpaceAround,
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .padding(top = 10.dp)
+                    ) {
+                        DiscountCard(productsListUiState[index]!!)
+                    }
+                } else {
+                    if (index % 2 != 1) {
                         Row(
                             horizontalArrangement = Arrangement.SpaceAround,
                             modifier = Modifier
                                 .fillMaxWidth()
                                 .padding(top = 10.dp)
                         ) {
-                            DiscountCard(products[index])
+                            DiscountCard(productsListUiState[index]!!)
-                        }
+                            DiscountCard(productsListUiState[index+1]!!)
-                    } else {
-                        if (index % 2 != 1) {
-                            Row(
-                                horizontalArrangement = Arrangement.SpaceAround,
-                                modifier = Modifier
-                                    .fillMaxWidth()
-                                    .padding(top = 10.dp)
-                            ) {
-                                DiscountCard(products[index])
-                                DiscountCard(products[index+1])
-                            }
                         }
                     }
-                    if (index == products.size - 1) {
+                }
-                        Spacer(modifier = Modifier.height(70.dp))
+                if (index == productsListUiState.itemCount - 1) {
-                    }
+                    Spacer(modifier = Modifier.height(70.dp))
                 }
             }
         }

app/src/main/java/com/example/shawarma/screens/home/HomeScreen.kt

@@ -20,7 +20,6 @@ import androidx.compose.material.ButtonDefaults
 import androidx.compose.material.Card
 import androidx.compose.material.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -32,6 +31,8 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import androidx.compose.ui.zIndex
 import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.paging.compose.collectAsLazyPagingItems
+import androidx.paging.compose.itemKey
 import com.example.shawarma.R
 import com.example.shawarma.data.models.ProductModel
 import com.example.shawarma.data.sharedpref.PreferencesManager
@@ -58,7 +59,7 @@ fun HomeScreen() {
 fun HomeList(){
     val homeViewModel: HomeViewModel = hiltViewModel<HomeViewModel>()
 
-    val products = homeViewModel.products.observeAsState().value
+    val productsListUiState = homeViewModel.productListUiState.collectAsLazyPagingItems()
 
 
     Box(
@@ -81,33 +82,34 @@ fun HomeList(){
             modifier = Modifier.padding(top = 80.dp)
         )
         {
-            if (products != null) {
+            items(
-                items(products.size) { index ->
+                count = productsListUiState.itemCount,
-                    if (index % 2 == 0 && index == products.size - 1) {
+                key = productsListUiState.itemKey()
+            ) { index ->
+                if (index % 2 == 0 && index == productsListUiState.itemCount - 1) {
+                    Row(
+                        horizontalArrangement = Arrangement.SpaceAround,
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .padding(top = 10.dp)
+                    ) {
+                        ProductCard(productsListUiState[index]!!)
+                    }
+                } else {
+                    if (index % 2 != 1) {
                         Row(
                             horizontalArrangement = Arrangement.SpaceAround,
                             modifier = Modifier
                                 .fillMaxWidth()
                                 .padding(top = 10.dp)
                         ) {
-                            ProductCard(products[index])
+                            ProductCard(productsListUiState[index]!!)
-                        }
+                            ProductCard(productsListUiState[index + 1]!!)
-                    } else {
-                        if (index % 2 != 1) {
-                            Row(
-                                horizontalArrangement = Arrangement.SpaceAround,
-                                modifier = Modifier
-                                    .fillMaxWidth()
-                                    .padding(top = 10.dp)
-                            ) {
-                                ProductCard(products[index])
-                                ProductCard(products[index + 1])
-                            }
                         }
                     }
-                    if (index == products.size - 1) {
+                }
-                        Spacer(modifier = Modifier.height(70.dp))
+                if (index == productsListUiState.itemCount - 1) {
-                    }
+                    Spacer(modifier = Modifier.height(70.dp))
                 }
             }
         }

app/src/main/java/com/example/shawarma/screens/products/ProductsScreen.kt

@@ -20,7 +20,6 @@ import androidx.compose.material.Card
 import androidx.compose.material.Icon
 import androidx.compose.material.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -32,6 +31,8 @@ import androidx.compose.ui.unit.sp
 import androidx.compose.ui.zIndex
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.navigation.NavHostController
+import androidx.paging.compose.collectAsLazyPagingItems
+import androidx.paging.compose.itemKey
 import com.example.shawarma.R
 import com.example.shawarma.data.models.ProductModel
 import com.example.shawarma.ui.theme.MarckFamily
@@ -60,7 +61,7 @@ fun ProductsScreen(navHostController: NavHostController) {
 fun ProductsList(navHostController: NavHostController){
     val productsViewModel: ProductsViewModel = hiltViewModel<ProductsViewModel>()
 
-    val products = productsViewModel.products.observeAsState().value
+    val products = productsViewModel.productListUiState.collectAsLazyPagingItems()
 
     Box(
         modifier = Modifier
@@ -103,13 +104,14 @@ fun ProductsList(navHostController: NavHostController){
             modifier = Modifier.padding(top = 160.dp)
         )
         {
-            if (products != null) {
+            items(
-                items(products.size) { index ->
+                products.itemCount,
-                    ProductItem(products[index], navHostController)
+                key = products.itemKey()
-                    Spacer(modifier = Modifier.height(20.dp))
+            ) { index ->
-                    if (index == products.size - 1) {
+                ProductItem(products[index]!!, navHostController)
-                        Spacer(modifier = Modifier.height(70.dp))
+                Spacer(modifier = Modifier.height(20.dp))
-                    }
+                if (index == products.itemCount - 1) {
+                    Spacer(modifier = Modifier.height(70.dp))
                 }
             }
         }

app/src/main/java/com/example/shawarma/viewmodels/HomeViewModel.kt

@@ -1,9 +1,8 @@
 package com.example.shawarma.viewmodels
 
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.paging.PagingData
 import com.example.shawarma.data.models.OrderModel
 import com.example.shawarma.data.models.OrderProductModel
 import com.example.shawarma.data.models.OrderStatus
@@ -12,6 +11,7 @@ import com.example.shawarma.data.repos.OrderProductRepository
 import com.example.shawarma.data.repos.OrderRepository
 import com.example.shawarma.data.repos.ProductRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.launch
 import java.util.Date
@@ -23,26 +23,11 @@ class HomeViewModel @Inject constructor(
     private val orderRepository: OrderRepository,
     private val orderProductRepository: OrderProductRepository
 ) : ViewModel() {
-    private val _products =  MutableLiveData<List<ProductModel>>()
-    val products: LiveData<List<ProductModel>>
-        get() = _products
 
-    private val _discounts=  MutableLiveData<List<ProductModel>>()
+    val productListUiState: Flow<PagingData<ProductModel>> = productRepository.getAllProductsPaged()
-    val discounts: LiveData<List<ProductModel>>
+
-        get() = _discounts
+    val discountListUiState: Flow<PagingData<ProductModel>> = productRepository.getAllDiscountsPaged()
 
-    init {
-        viewModelScope.launch {
-            productRepository.getAll().collect {
-                _products.postValue(it)
-            }
-        }
-        viewModelScope.launch {
-            productRepository.getDiscounts().collect {
-                _discounts.postValue(it)
-            }
-        }
-    }
 
     fun addProductToCart(productId: Int, userId: String) {
         if (userId == "null") return

app/src/main/java/com/example/shawarma/viewmodels/ProductsViewModel.kt

@@ -4,9 +4,11 @@ import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.paging.PagingData
 import com.example.shawarma.data.models.ProductModel
 import com.example.shawarma.data.repos.ProductRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
@@ -18,13 +20,7 @@ class ProductsViewModel  @Inject constructor(
     val products: LiveData<List<ProductModel>>
         get() = _products
 
-    init {
+    val productListUiState: Flow<PagingData<ProductModel>> = productRepository.getAllItemsPaged()
-        viewModelScope.launch {
-            productRepository.getItems().collect {
-                _products.postValue(it)
-            }
-        }
-    }
 
     fun deleteProduct(product: ProductModel) {
         viewModelScope.launch {