気象庁による 地震・津波のお知らせ

lib/core/extension/async_value.dart

@@ -1,16 +1,64 @@
-import 'dart:async';
+// ignore_for_file: avoid_positional_boolean_parameters
 
+import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 
-extension AsyncValueExt<T> on AsyncValue<T> {
-  Future<AsyncValue<T>> guardPlus(
-    Future<T> Function() future,
-  ) async {
+// https://zenn.dev/k9i/articles/b8c333e1bb8b9b
+extension AsyncValueX<T> on AsyncValue<T> {
+  /// guard関数の拡張版
+  /// 例外時に前回のデータを持たせてエラーを返す
+  Future<AsyncValue<T>> guardPlus(Future<T> Function() future) async {
     try {
-      return AsyncValue<T>.data(await future());
+      return AsyncValue.data(await future());
       // ignore: avoid_catches_without_on_clauses
-    } catch (e, st) {
-      return AsyncValue<T>.error(e, st).copyWithPrevious(this);
+    } catch (err, stack) {
+      // 前回のデータを持たせてエラーを返す
+      return AsyncValue<T>.error(err, stack).copyWithPrevious(this);
+    }
+  }
+
+  /// when関数の拡張版
+  ///
+  /// [skipErrorOnHasValue]がtrueの時はデータがある場合のエラーをスキップする
+  /// ページングの2ページ目以降でエラー時に、取得ずみデータを表示する場合などに使用する
+  R whenPlus<R>({
+    bool skipLoadingOnReload = false,
+    bool skipLoadingOnRefresh = true,
+    bool skipError = false,
+    bool skipErrorOnHasValue = false,
+    required R Function(T data, bool hasError) data,
+    required R Function(Object error, StackTrace stackTrace) error,
+    required R Function() loading,
+  }) {
+    if (skipErrorOnHasValue) {
+      if (hasValue && hasError) {
+        return data(requireValue, true);
+      }
+    }
+
+    return when(
+      skipLoadingOnReload: skipLoadingOnReload,
+      skipLoadingOnRefresh: skipLoadingOnRefresh,
+      skipError: skipError,
+      data: (d) => data(d, hasError),
+      error: error,
+      loading: loading,
+    );
+  }
+
+  /// エラー時にスナックバーを表示する
+  void showSnackbarOnError(
+    BuildContext context, {
+    String defaultMessage = 'エラーが発生しました',
+  }) {
+    if (!isLoading && hasError) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text(
+            error!.toString(),
+          ),
+        ),
+      );
     }
   }
 }

lib/core/foundation/result.dart

@@ -1,27 +1,43 @@
-import 'package:freezed_annotation/freezed_annotation.dart';
+import 'dart:async';
 
-part 'result.freezed.dart';
+/// sealed classに準拠したResultクラスを生成
+sealed class Result<S, E extends Exception> {
+  const Result();
 
-@freezed
-sealed class Result<T, R> with _$Result<T, R> {
-  const Result._();
-  const factory Result.success(T value) = Success<T, R>;
-  const factory Result.failure(R error) = Failure<T, R>;
+  static Future<Result<V, Exception>> capture<V>(
+    FutureOr<V> Function() fn,
+  ) async {
+    try {
+      return Success(await fn.call());
+    } on Exception catch (e, stackTrace) {
+      return Failure(e, stackTrace);
+    }
+  }
 
-  T? get valueOrNull => when(
-        success: (value) => value,
-        failure: (_) => null,
-      );
+  static Future<Result<V, E>> captureSelected<V, E extends Exception>(
+    FutureOr<V> Function() fn,
+  ) async {
+    try {
+      return Success(await fn.call());
+    } on E catch (e, stackTrace) {
+      return Failure(e, stackTrace);
+    }
+  }
 
-  R? get errorOrNull => when(
-        success: (_) => null,
-        failure: (error) => error,
-      );
+  static Result<V, Exception> success<V>(V value) => Success(value);
+  static Result<V, Exception> failure<V>(Exception exception) =>
+      Failure(exception);
+}
 
-  bool get isSuccess => when(
-        success: (_) => true,
-        failure: (_) => false,
-      );
+/// Resultクラスに準拠したSuccessクラス
+final class Success<S, E extends Exception> extends Result<S, E> {
+  const Success(this.value);
+  final S value;
+}
 
-  bool get isFailure => !isSuccess;
+/// Resultクラスに準拠したFailureクラス
+final class Failure<S, E extends Exception> extends Result<S, E> {
+  const Failure(this.exception, [this.stackTrace]);
+  final E exception;
+  final StackTrace? stackTrace;
 }