Merge pull request #26 from Q42/feature/viewstatestring

ADD ViewStateString

README.MD

@@ -108,7 +108,9 @@ Model Entities live in the data layer and are the local storage objects.
 Models map from XDTO to XEntity to X and then probably into a viewstate. Mapping is always done in
 the _outside layer_, before being transported to the inner layer.
 See [the diagram](#clean-architecture) for more info.
-- Writing mapping functions between models, entities and DTO ojects is boring and cumbersome: let GitHub Copilot or some other AI tool in Android Studio generate your mapping functions.
+
+- Writing mapping functions between models, entities and DTO ojects is boring and cumbersome: let
+  GitHub Copilot or some other AI tool in Android Studio generate your mapping functions.
 
 #### Core modules
 
@@ -179,6 +181,11 @@ modules.
 We use a version catalog (toml) file for versioning. This is the latest feature from Gradle
 currently. It can be shared over (included) projects.
 
+#### ViewStateString
+
+ViewStateStrings enables you to move String logic from the View to the ViewModel, especially plurals
+or replacement parameter logic.
+
 ### Compose Previews
 
 Use `@PreviewLightDark` to generate two previews from one function, one dark and one light. You
@@ -212,7 +219,7 @@ added [extra logic to navigate from ViewModel](https://medium.com/@ffvanderlaan/
 - Call `InitNavigator(navigator, viewModel)` from your screen.
 - Call `navigateTo(destination)` from your ViewModel to navigate somewhere. There are also popUpTo
   methods, etc.
-  
+
   You can call navigateTo with a `AppGraphRoutes` (in core.navigation) to navigate to the root of a
   different
   graph route.

build.gradle

@@ -1,3 +1,5 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
 buildscript {
     ext {
         minSdkVersion = 29
@@ -13,3 +15,16 @@ plugins { // sets class paths only (because of 'apply false')
     alias libs.plugins.hilt apply false
     alias libs.plugins.ksp apply false
 }
+
+allprojects {
+    tasks.withType(KotlinCompile).configureEach {
+        compilerOptions {
+            freeCompilerArgs.add("-opt-in=kotlinx.coroutines.ExperimentalCoroutinesApi")
+            freeCompilerArgs.add("-opt-in=androidx.compose.foundation.ExperimentalFoundationApi")
+            freeCompilerArgs.add("-opt-in=androidx.compose.ui.ExperimentalComposeUiApi")
+            freeCompilerArgs.add("-opt-in=androidx.compose.material3.ExperimentalMaterial3Api")
+            freeCompilerArgs.add("-opt-in=androidx.compose.ui.text.ExperimentalTextApi")
+            freeCompilerArgs.add("-opt-in=androidx.media3.common.util.UnstableApi")
+        }
+    }
+}

core/ui/src/main/kotlin/nl/q42/template/ui/compose/ViewStateStringResolver.kt

@@ -0,0 +1,28 @@
+package nl.q42.template.ui.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.res.pluralStringResource
+import androidx.compose.ui.res.stringResource
+import nl.q42.template.ui.presentation.ViewStateString
+
+/**
+ * Resolve a ViewStateString to a string from a Compose context.
+ */
+@Composable
+fun ViewStateString.get(): String {
+    return when (this) {
+        is ViewStateString.Res -> {
+            // Map any nested ViewStateStrings to their resolved values.
+            val resolvedArguments =
+                this.formatArgs.map { if (it is ViewStateString) it.get() else it }
+                    .toTypedArray()
+            stringResource(id = this.stringRes, formatArgs = resolvedArguments)
+        }
+
+        is ViewStateString.PluralRes -> {
+            pluralStringResource(id = pluralRes, count = count, count)
+        }
+
+        is ViewStateString.Basic -> this.value
+    }
+}

core/ui/src/main/kotlin/nl/q42/template/ui/presentation/ViewStateString.kt

@@ -0,0 +1,41 @@
+package nl.q42.template.ui.presentation
+
+import androidx.annotation.PluralsRes
+import androidx.annotation.StringRes
+
+/**
+ * This class enables you to use string logic in the ViewModel, especially plurals or replacement parameter logic.
+ *
+ * All strings will be refreshed on view recreation (i.e. after locale or other config changes).
+ *
+ * There is one edge case: the formatArgs are not refreshed on config changes, so if you use a string with a
+ * replacement parameter that is f.e. a localized date string, move your logic to the view instead of using [ViewStateString].
+ */
+sealed class ViewStateString {
+    data class Res(
+        @StringRes val stringRes: Int,
+        val formatArgs: List<Any> = listOf()
+    ) : ViewStateString() {
+        // Allow constructing ViewStateString.Res with varargs instead of passing a list
+        @Suppress("unused")
+        constructor(@StringRes stringRes: Int, vararg formatArgs: Any) : this(stringRes, formatArgs.toList())
+    }
+
+    data class PluralRes(
+        @PluralsRes val pluralRes: Int,
+        val count: Int,
+        val formatArgs: List<Any> = listOf(count)
+    ) : ViewStateString() {
+        // Allow constructing ViewStateString.PluralRes with varargs instead of passing a list
+        @Suppress("unused")
+        constructor(@PluralsRes pluralRes: Int, count: Int, vararg formatArgs: Any) : this(
+            pluralRes,
+            count,
+            formatArgs.toList()
+        )
+    }
+
+    data class Basic(val value: String) : ViewStateString()
+}
+
+fun String.toViewStateString(): ViewStateString.Basic = ViewStateString.Basic(this)

feature/home/src/main/kotlin/nl/q42/template/presentation/home/HomeViewModel.kt

@@ -9,9 +9,11 @@ import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import nl.q42.template.actionresult.data.handleAction
 import nl.q42.template.domain.user.usecase.GetUserUseCase
+import nl.q42.template.feature.home.R
 import nl.q42.template.navigation.AppGraphRoutes
 import nl.q42.template.navigation.viewmodel.RouteNavigator
 import nl.q42.template.ui.home.destinations.HomeSecondScreenDestination
+import nl.q42.template.ui.presentation.ViewStateString
 import javax.inject.Inject
 
 @HiltViewModel
@@ -42,7 +44,13 @@ class HomeViewModel @Inject constructor(
             handleAction(
                 getUserUseCase(),
                 onError = { _uiState.update { HomeViewState.Error } },
-                onSuccess = { result -> _uiState.update { HomeViewState.Data(result.email) } },
+                onSuccess = { result ->
+                    _uiState.update {
+                        HomeViewState.Data(
+                            ViewStateString.Res(R.string.emailTitle, result.email)
+                        )
+                    }
+                },
             )
         }
     }

feature/home/src/main/kotlin/nl/q42/template/presentation/home/HomeViewState.kt

@@ -1,8 +1,10 @@
 package nl.q42.template.presentation.home
 
+import nl.q42.template.ui.presentation.ViewStateString
+
 sealed class HomeViewState {
-    data class Data(val userEmail: String? = null) : HomeViewState()
+    data class Data(val userEmailTitle: ViewStateString? = null) : HomeViewState()
     object Loading : HomeViewState()
     object Error : HomeViewState()
     object Empty : HomeViewState()
-}
+}

feature/home/src/main/kotlin/nl/q42/template/ui/home/HomeContent.kt

@@ -9,6 +9,8 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment.Companion.CenterHorizontally
 import androidx.compose.ui.Modifier
 import nl.q42.template.presentation.home.HomeViewState
+import nl.q42.template.ui.compose.get
+import nl.q42.template.ui.presentation.toViewStateString
 import nl.q42.template.ui.theme.PreviewAppTheme
 import nl.q42.template.ui.theme.PreviewLightDark
 
@@ -31,7 +33,10 @@ internal fun HomeContent(
          * This is dummy. Use the strings file IRL.
          */
         when (viewState) {
-            is HomeViewState.Data -> Text(text = "Email: ${viewState.userEmail}")
+            is HomeViewState.Data -> viewState.userEmailTitle?.let { userEmailTitle ->
+                Text(text = userEmailTitle.get())
+            }
+
             HomeViewState.Empty -> {}
             HomeViewState.Error -> Text(text = "Error")
             HomeViewState.Loading -> Text(text = "Loading")
@@ -78,6 +83,6 @@ private fun HomeContentEmptyPreview() {
 @Composable
 private fun HomeContentDataPreview() {
     PreviewAppTheme {
-        HomeContent(HomeViewState.Data("preview@preview.com"), {}, {}, {})
+        HomeContent(HomeViewState.Data("preview@preview.com".toViewStateString()), {}, {}, {})
     }
-}
+}

feature/home/src/main/res/values-nl/strings.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="emailTitle">Email adres %s</string>
+</resources>

feature/home/src/main/res/values/strings.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="emailTitle">Email address %s</string>
+</resources>

feature/home/src/test/kotlin/nl/q42/template/presentation/home/HomeViewModelTest.kt

@@ -2,26 +2,27 @@ package nl.q42.template.presentation.home
 
 import app.cash.turbine.test
 import io.mockk.coEvery
-import io.mockk.every
 import io.mockk.mockk
 import junit.framework.TestCase.assertEquals
+import junit.framework.TestCase.assertTrue
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.test.runTest
 import nl.q42.template.actionresult.domain.ActionResult
 import nl.q42.template.domain.user.model.User
 import nl.q42.template.domain.user.usecase.GetUserUseCase
+import nl.q42.template.ui.presentation.ViewStateString
 import org.junit.Rule
 import org.junit.Test
 import kotlin.time.Duration.Companion.seconds
 
-
-class HomeViewModelTest(){
+class HomeViewModelTest() {
     @get:Rule
     val mainDispatcherRule = MainDispatcherRule()
+
     @Test
-    fun `WHEN I subscribe to uiState with a slow UserUseCase THEN I get the loading state and expected email address`() = runTest{
+    fun `WHEN I subscribe to uiState with a slow UserUseCase THEN I get the loading state and expected email address`() = runTest {
         val getUserUseCaseMock: GetUserUseCase = mockk()
-        coEvery {getUserUseCaseMock.invoke() }.coAnswers {
+        coEvery { getUserUseCaseMock.invoke() }.coAnswers {
             // demonstration of test scheduler. This does not actually block the test for 4 seconds
             delay(4.seconds)
             ActionResult.Success(User("test@test.com"))
@@ -30,27 +31,29 @@ class HomeViewModelTest(){
         val viewModel = HomeViewModel(getUserUseCaseMock, mockk())
 
         viewModel.uiState.test {
-            val expectedData: HomeViewState = HomeViewState.Data("test@test.com")
 
             assertEquals(HomeViewState.Loading, awaitItem())
-            assertEquals(expectedData, awaitItem())
+            val viewState = awaitItem()
+            assertTrue(viewState is HomeViewState.Data)
+            assertTrue((viewState as HomeViewState.Data).userEmailTitle is ViewStateString.Res)
         }
     }
 
     @Test
-    fun `WHEN I subscribe to uiState with a fast UserUseCase THEN I get expected email address immediately`() = runTest{
+    fun `WHEN I subscribe to uiState with a fast UserUseCase THEN I get expected email address immediately`() = runTest {
         val getUserUseCaseMock: GetUserUseCase = mockk()
         coEvery { getUserUseCaseMock.invoke() }.returns(
-            ActionResult.Success(User("test@test.com")
-        ))
-
+            ActionResult.Success(
+                User("test@test.com")
+            )
+        )
 
         val viewModel = HomeViewModel(getUserUseCaseMock, mockk())
 
         viewModel.uiState.test {
-            val expectedData: HomeViewState = HomeViewState.Data("test@test.com")
-            assertEquals(expectedData, awaitItem())
+            val viewState = awaitItem()
+            assertTrue(viewState is HomeViewState.Data)
+            assertTrue((viewState as HomeViewState.Data).userEmailTitle is ViewStateString.Res)
         }
     }
-
 }