update(add): showing error after EditText's text changed

Author: hoc081098

app/src/main/java/com/hoc/flowmvi/FlowBinding+Exts+Utils.kt

@@ -6,6 +6,7 @@ import android.graphics.Color
 import android.graphics.drawable.ColorDrawable
 import android.text.Editable
 import android.text.TextWatcher
+import android.util.Log
 import android.view.View
 import android.widget.EditText
 import android.widget.Toast
@@ -19,6 +20,27 @@ import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.*
 import java.util.concurrent.atomic.AtomicBoolean
 import java.util.concurrent.atomic.AtomicReference
+import kotlin.coroutines.EmptyCoroutineContext
+
+@ExperimentalCoroutinesApi
+fun EditText.firstChange(): Flow<Unit> {
+  return callbackFlow<Unit> {
+    val listener = object : TextWatcher {
+      override fun afterTextChanged(s: Editable?) = Unit
+      override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) = Unit
+      override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+        offer(Unit)
+      }
+    }.also { addTextChangedListener(it) }
+
+    awaitClose {
+      Dispatchers.Main.dispatch(EmptyCoroutineContext) {
+        removeTextChangedListener(listener)
+        Log.d("###", "removeTextChangedListener $listener ${this@firstChange}")
+      }
+    }
+  }.take(1)
+}
 
 @ExperimentalCoroutinesApi
 @CheckResult

app/src/main/java/com/hoc/flowmvi/ui/add/AddActivity.kt

@@ -10,6 +10,7 @@ import androidx.transition.AutoTransition
 import androidx.transition.TransitionManager
 import com.hoc.flowmvi.clicks
 import com.hoc.flowmvi.databinding.ActivityAddBinding
+import com.hoc.flowmvi.firstChange
 import com.hoc.flowmvi.textChanges
 import com.hoc.flowmvi.toast
 import com.hoc.flowmvi.ui.add.AddContract.*
@@ -81,7 +82,7 @@ class AddActivity : AppCompatActivity(), View {
     } else {
       null
     }
-    if (addBinding.emailEditText.error != emailErrorMessage) {
+    if (viewState.emailChanged && addBinding.emailEditText.error != emailErrorMessage) {
       addBinding.emailEditText.error = emailErrorMessage
     }
 
@@ -90,7 +91,7 @@ class AddActivity : AppCompatActivity(), View {
     } else {
       null
     }
-    if (addBinding.firstNameEditText.error != firstNameErrorMessage) {
+    if (viewState.firstNameChanged && addBinding.firstNameEditText.error != firstNameErrorMessage) {
       addBinding.firstNameEditText.error = firstNameErrorMessage
     }
 
@@ -99,7 +100,7 @@ class AddActivity : AppCompatActivity(), View {
     } else {
       null
     }
-    if (addBinding.lastNameEditText.error != lastNameErrorMessage) {
+    if (viewState.lastNameChanged && addBinding.lastNameEditText.error != lastNameErrorMessage) {
       addBinding.lastNameEditText.error = lastNameErrorMessage
     }
 
@@ -116,27 +117,35 @@ class AddActivity : AppCompatActivity(), View {
 
   private fun setupViews() = Unit
 
-  override fun intents(): Flow<ViewIntent> {
-    return merge(
-        addBinding
-            .emailEditText
+  override fun intents(): Flow<ViewIntent> = addBinding.run {
+    merge(
+        emailEditText
             .editText!!
             .textChanges()
             .map { ViewIntent.EmailChanged(it?.toString()) },
-        addBinding
-            .firstNameEditText
+        firstNameEditText
             .editText!!
             .textChanges()
             .map { ViewIntent.FirstNameChanged(it?.toString()) },
-        addBinding
-            .lastNameEditText
+        lastNameEditText
             .editText!!
             .textChanges()
             .map { ViewIntent.LastNameChanged(it?.toString()) },
-        addBinding
-            .addButton
+        addButton
             .clicks()
-            .map { ViewIntent.Submit }
+            .map { ViewIntent.Submit },
+        emailEditText
+            .editText!!
+            .firstChange()
+            .map { ViewIntent.EmailChangedFirstTime },
+        firstNameEditText
+            .editText!!
+            .firstChange()
+            .map { ViewIntent.FirstNameChangedFirstTime },
+        lastNameEditText
+            .editText!!
+            .firstChange()
+            .map { ViewIntent.LastNameChangedFirstTime },
     )
   }
 }

app/src/main/java/com/hoc/flowmvi/ui/add/AddContract.kt

@@ -16,12 +16,18 @@ interface AddContract {
 
   data class ViewState(
       val errors: Set<ValidationError>,
-      val isLoading: Boolean
+      val isLoading: Boolean,
+      val emailChanged: Boolean,
+      val firstNameChanged: Boolean,
+      val lastNameChanged: Boolean,
   ) {
     companion object {
       fun initial() = ViewState(
           errors = emptySet(),
-          isLoading = false
+          isLoading = false,
+          emailChanged = false,
+          firstNameChanged = false,
+          lastNameChanged = false,
       )
     }
   }
@@ -30,7 +36,12 @@ interface AddContract {
     data class EmailChanged(val email: String?) : ViewIntent()
     data class FirstNameChanged(val firstName: String?) : ViewIntent()
     data class LastNameChanged(val lastName: String?) : ViewIntent()
+
     object Submit : ViewIntent()
+
+    object EmailChangedFirstTime : ViewIntent()
+    object FirstNameChangedFirstTime : ViewIntent()
+    object LastNameChangedFirstTime : ViewIntent()
   }
 
   sealed class PartialStateChange {
@@ -53,6 +64,20 @@ interface AddContract {
         }
       }
     }
+
+    sealed class FirstChange : PartialStateChange() {
+      object EmailChangedFirstTime : FirstChange()
+      object FirstNameChangedFirstTime : FirstChange()
+      object LastNameChangedFirstTime : FirstChange()
+
+      override fun reduce(viewState: ViewState): ViewState {
+        return when (this) {
+          EmailChangedFirstTime -> viewState.copy(emailChanged = true)
+          FirstNameChangedFirstTime -> viewState.copy(firstNameChanged = true)
+          LastNameChangedFirstTime -> viewState.copy(lastNameChanged = true)
+        }
+      }
+    }
   }
 
   sealed class SingleEvent {

app/src/main/java/com/hoc/flowmvi/ui/add/AddVM.kt

@@ -52,6 +52,9 @@ class AddVM(private val addUser: AddUserUseCase) : ViewModel() {
             change.user,
             change.throwable
         )
+        PartialStateChange.FirstChange.EmailChangedFirstTime -> return@onEach
+        PartialStateChange.FirstChange.FirstNameChangedFirstTime -> return@onEach
+        PartialStateChange.FirstChange.LastNameChangedFirstTime -> return@onEach
       }
       _eventChannel.send(event)
     }
@@ -98,11 +101,21 @@ class AddVM(private val addUser: AddUserUseCase) : ViewModel() {
               .catch { emit(PartialStateChange.AddUser.AddUserFailure(user, it)) }
         }
 
+    val firstChanges = merge(
+        filterIsInstance<ViewIntent.EmailChangedFirstTime>()
+            .map { PartialStateChange.FirstChange.EmailChangedFirstTime },
+        filterIsInstance<ViewIntent.FirstNameChangedFirstTime>()
+            .map { PartialStateChange.FirstChange.FirstNameChangedFirstTime },
+        filterIsInstance<ViewIntent.LastNameChangedFirstTime>()
+            .map { PartialStateChange.FirstChange.LastNameChangedFirstTime }
+    )
+
     return merge(
         userFormFlow
             .map { it.errors }
             .map { PartialStateChange.ErrorsChanged(it) },
-        addUserChanges
+        addUserChanges,
+        firstChanges,
     )
   }