Add isEmpty to BaseRequestCubit

packages/leancode_cubit_utils/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.0
+
+* Add `isEmpty` to `BaseRequestCubit`
+
 ## 0.1.0
 
 * Extract `cqrs` support to `leancode_cubit_utils_cqrs`

packages/leancode_cubit_utils/example/lib/main.dart

@@ -65,6 +65,7 @@ void main() {
           requestMode: RequestMode.replace,
           onLoading: (BuildContext context) =>
               const CircularProgressIndicator(),
+          onEmpty: (BuildContext context) => const Text('Empty'),
           onError: (
             BuildContext context,
             RequestErrorState<dynamic, dynamic> error,

packages/leancode_cubit_utils/lib/src/request/request_config_provider.dart

@@ -9,12 +9,16 @@ class RequestLayoutConfig {
   /// Creates a new [RequestLayoutConfig].
   RequestLayoutConfig({
     required this.onLoading,
+    required this.onEmpty,
     required this.onError,
   });
 
   /// The builder that creates a widget when request is loading.
   final WidgetBuilder onLoading;
 
+  /// The builder that creates a widget when request returns empty data.
+  final WidgetBuilder? onEmpty;
+
   /// The builder that creates a widget when request failed.
   final RequestErrorBuilder<dynamic> onError;
 }
@@ -28,6 +32,7 @@ class RequestLayoutConfigProvider extends StatelessWidget {
     required this.onLoading,
     required this.onError,
     required this.child,
+    this.onEmpty,
   });
 
   /// The default request mode used by all [RequestCubit]s.
@@ -36,6 +41,9 @@ class RequestLayoutConfigProvider extends StatelessWidget {
   /// The builder that creates a widget when request is loading.
   final WidgetBuilder onLoading;
 
+  /// The builder that creates a widget when request returns empty data.
+  final WidgetBuilder? onEmpty;
+
   /// The builder that creates a widget when request failed.
   final RequestErrorBuilder<dynamic> onError;
 
@@ -52,6 +60,7 @@ class RequestLayoutConfigProvider extends StatelessWidget {
     return Provider(
       create: (context) => RequestLayoutConfig(
         onLoading: onLoading,
+        onEmpty: onEmpty,
         onError: onError,
       ),
       child: child,

packages/leancode_cubit_utils/lib/src/request/request_cubit.dart

@@ -15,6 +15,9 @@ typedef ArgsRequest<TArgs, TRes> = Future<TRes> Function(TArgs);
 /// Signature for a function that maps request response of to the output type.
 typedef ResponseMapper<TRes, TOut> = TOut Function(TRes);
 
+/// Signature for a function that checks if the request response is empty.
+typedef EmptyChecker<TRes> = bool Function(TRes);
+
 /// Signature for a function that maps request error to other state.
 typedef ErrorMapper<TOut, TError> = Future<TOut> Function(
   RequestErrorState<TOut, TError>,
@@ -116,6 +119,9 @@ abstract class BaseRequestCubit<TRes, TData, TOut, TError>
   /// Maps the given [data] to the output type [TOut].
   TOut map(TData data);
 
+  /// Override this to check if the given [data] is empty.
+  bool isEmpty(TOut data) => false;
+
   /// Handles the given [errorState] and returns the corresponding state.
   Future<RequestErrorState<TOut, TError>> handleError(
     RequestErrorState<TOut, TError> errorState,
@@ -231,6 +237,15 @@ final class RequestSuccessState<TOut, TError>
   List<Object?> get props => [data];
 }
 
+/// Represents a successful request with empty data.
+final class RequestEmptyState<TOut, TError> extends RequestState<TOut, TError> {
+  /// Creates a new [RequestEmptyState]..
+  RequestEmptyState();
+
+  @override
+  List<Object?> get props => [];
+}
+
 /// Represents a failed request.
 final class RequestErrorState<TOut, TError> extends RequestState<TOut, TError> {
   /// Creates a new [RequestErrorState] with the given [error], [exception] and

packages/leancode_cubit_utils/lib/src/request/request_cubit_builder.dart

@@ -26,6 +26,7 @@ class RequestCubitBuilder<TOut, TError> extends StatelessWidget {
     required this.builder,
     this.onInitial,
     this.onLoading,
+    this.onEmpty,
     this.onError,
     this.onErrorCallback,
   });
@@ -42,6 +43,9 @@ class RequestCubitBuilder<TOut, TError> extends StatelessWidget {
   /// The builder that creates a widget when request is loading.
   final WidgetBuilder? onLoading;
 
+  /// The builder that creates a widget when request returns empty data.
+  final WidgetBuilder? onEmpty;
+
   /// The builder that creates a widget when request failed.
   final RequestErrorBuilder<TError>? onError;
 
@@ -66,6 +70,9 @@ class RequestCubitBuilder<TOut, TError> extends StatelessWidget {
           RequestRefreshState(:final data) => data != null
               ? builder(context, data)
               : onLoading?.call(context) ?? config.onLoading(context),
+          RequestEmptyState() => onEmpty?.call(context) ??
+              config.onEmpty?.call(context) ??
+              const SizedBox(),
           RequestErrorState() => onError?.call(
                 context,
                 state,

packages/leancode_cubit_utils/pubspec.yaml

@@ -1,6 +1,6 @@
 name: leancode_cubit_utils
 description: A collection of cubits and widgets that facilitate the creation of repetitive pages, eliminating boilerplate.
-version: 0.1.0
+version: 0.2.0
 repository: https://github.com/leancodepl/leancode_cubit_utils
 
 environment:

packages/leancode_cubit_utils/test/request_cubit_builder_test.dart

@@ -22,6 +22,7 @@ class TestPage extends StatelessWidget {
   Widget build(BuildContext context) {
     return RequestLayoutConfigProvider(
       onLoading: (context) => const Text('Loading...'),
+      onEmpty: (context) => const Text('Empty!'),
       onError: (context, error, onErrorCallback) => const Text('Error!'),
       child: MaterialApp(
         home: Scaffold(body: child),
@@ -45,6 +46,12 @@ void main() {
       (_) async => http.Response('', StatusCode.badRequest.value),
     );
 
+    when(
+      () => client.get(Uri.parse('2')),
+    ).thenAnswer(
+      (_) async => http.Response('', StatusCode.ok.value),
+    );
+
     testWidgets(
         'shows default loading and error widget when no onLoading and onError provided',
         (tester) async {
@@ -67,6 +74,28 @@ void main() {
       expect(find.text('Error!'), findsOneWidget);
     });
 
+    testWidgets(
+        'shows default loading and empty widget when no onLoading and onEmpty provided',
+        (tester) async {
+      final queryCubit = TestArgsRequestCubit('TestQueryCubit', client: client);
+
+      await tester.pumpWidget(
+        TestPage(
+          child: RequestCubitBuilder(
+            cubit: queryCubit,
+            builder: (context, data) => Text(data),
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+      expect(find.text('Loading...'), findsOneWidget);
+      unawaited(queryCubit.run('2'));
+      await tester.pump();
+      expect(find.text('Loading...'), findsOneWidget);
+      await tester.pump();
+      expect(find.text('Empty!'), findsOneWidget);
+    });
+
     testWidgets('shows custom loading and error widget when provided',
         (tester) async {
       final queryCubit = TestArgsRequestCubit('TestQueryCubit', client: client);

packages/leancode_cubit_utils/test/utils/test_request_cubit.dart

@@ -8,8 +8,13 @@ mixin RequestResultHandler<TOut>
   @override
   Future<RequestState<TOut, int>> handleResult(http.Response result) async {
     if (result.statusCode == StatusCode.ok.value) {
+      final data = map(result.body);
+      if (isEmpty(data)) {
+        logger.warning('Query success but data is empty');
+        return RequestEmptyState();
+      }
       logger.info('Query success. Data: ${result.body}');
-      return RequestSuccessState(map(result.body));
+      return RequestSuccessState(data);
     } else {
       logger.severe('Query error. Status code: ${result.statusCode}');
       try {
@@ -44,6 +49,11 @@ class TestRequestCubit extends RequestCubit<http.Response, String, String, int>
     return 'Mapped $data';
   }
 
+  @override
+  bool isEmpty(String data) {
+    return data.isEmpty;
+  }
+
   @override
   Future<http.Response> request() {
     return client.get(Uri.parse(id));
@@ -74,6 +84,9 @@ class TestArgsRequestCubit
   @override
   String map(String data) => data;
 
+  @override
+  bool isEmpty(String data) => data.isEmpty;
+
   @override
   Future<http.Response> request(String args) {
     return client.get(Uri.parse(args));