made use of first class citizen objects as json validator functions

backend-dart/lib/application/repository/project_repository_impl.dart

@@ -27,7 +27,7 @@ class ProjectRepositoryImpl implements ProjectRepository {
   }
 
   @override
-  TaskEither<IError, void> delete(String id) {
+  TaskEither<IError, Project> delete(String id) {
     return database.projects.delete(id);
   }
 

backend-dart/lib/application/repository/project_task_repository_impl.dart

@@ -32,7 +32,7 @@ class ProjectTaskRepositoryImpl implements ProjectTaskRepository {
   }
 
   @override
-  TaskEither<IError, void> delete(String id) {
+  TaskEither<IError, ProjectTask> delete(String id) {
     return database.tasks.delete(id);
   }
 

backend-dart/lib/application/repository/time_entry_repository_impl.dart

@@ -37,7 +37,7 @@ class TimeEntryRepositoryImpl implements TimeEntryRepository {
   }
 
   @override
-  TaskEither<IError, void> delete(String id) {
+  TaskEither<IError, TimeEntry> delete(String id) {
     return database.timeEntries.delete(id);
   }
 

backend-dart/lib/application/repository/user_repository_impl.dart

@@ -34,7 +34,7 @@ class UserRepositoryImpl implements UserRepository {
   }
 
   @override
-  TaskEither<IError, void> delete(String id) {
+  TaskEither<IError, User> delete(String id) {
     return database.users.delete(id);
   }
 

backend-dart/lib/application/service/dto/user_dto.dart

@@ -14,7 +14,8 @@ class UserDto with _$UserDto {
   }) = _UserDto;
 
   /// JSON-Serialisierung
-  factory UserDto.fromJson(Map<String, dynamic> json) => _$UserDtoFromJson(json);
+  factory UserDto.fromJson(Map<String, dynamic> json) =>
+      _$UserDtoFromJson(json);
 }
 
 @freezed

backend-dart/lib/application/service/project_service.dart

@@ -22,8 +22,8 @@ class ProjectService {
         .findAll()
         .flatMap(mapper.listTo)
         .map((projects) => projects.map((project) => project.toJson()).toList())
-        .match((left) => ResponseHelpers.fromError(left),
+        .map(jsonEncode)
-            (right) => Response.ok(jsonEncode(right)))
+        .toResponse()
         .run();
   }
 
@@ -32,35 +32,34 @@ class ProjectService {
     return projects
         .findById(projectId)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.post('/')
   Future<Response> createProject(Request request) async {
     return requestToJson(request)
-        .flatMap((json) =>
+        .flatMap(validateJsonKeys(['name', 'userId'])) // Add required fields
-            validateJsonKeys(json, ['name', 'userId'])) // Add required fields
         .flatMap((json) => decodeJson(json, ProjectCreateDto.fromJson))
         .flatMap(mapper.fromCreateTo)
         .flatMap(projects.create)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.put('/<projectId>')
   Future<Response> updateProject(Request request, String projectId) async {
     return requestToJson(request)
-        .flatMap((json) => validateJsonKeys(json, []))
+        .flatMap(validateJsonKeys([]))
         .flatMap((json) => decodeJson(json, ProjectUpdateDto.fromJson))
         .flatMap((dto) => mapper.fromUpdateTo(dto, projectId))
         .flatMap(projects.update)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
@@ -68,8 +67,9 @@ class ProjectService {
   Future<Response> deleteProject(Request request, String projectId) async {
     return projects
         .delete(projectId)
-        .match((left) => ResponseHelpers.fromError(left),
+        .flatMap(mapper.to)
-            (right) => Response.ok('project deleted'))
+        .map((dto) => dto.toJson())
+        .toResponse()
         .run();
   }
 

backend-dart/lib/application/service/project_task_service.dart

@@ -22,8 +22,8 @@ class ProjectTaskService {
         .findAll()
         .flatMap(mapper.listTo)
         .map((tasks) => tasks.map((task) => task.toJson()).toList())
-        .match((left) => ResponseHelpers.fromError(left),
+        .map(jsonEncode)
-            (right) => Response.ok(jsonEncode(right)))
+        .toResponse()
         .run();
   }
 
@@ -32,35 +32,34 @@ class ProjectTaskService {
     return tasks
         .findById(taskId)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.post('/')
   Future<Response> createTask(Request request) async {
     return requestToJson(request)
-        .flatMap((json) =>
+        .flatMap(validateJsonKeys(['name', 'projectId'])) // Add required fields
-            validateJsonKeys(json, ['name', 'projectId'])) // Add required fields
         .flatMap((json) => decodeJson(json, ProjectTaskCreateDto.fromJson))
         .flatMap(mapper.fromCreateTo)
         .flatMap(tasks.create)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.put('/<taskId>')
   Future<Response> updateTask(Request request, String taskId) async {
     return requestToJson(request)
-        .flatMap((json) => validateJsonKeys(json, []))
+        .flatMap(validateJsonKeys([]))
         .flatMap((json) => decodeJson(json, ProjectTaskUpdateDto.fromJson))
         .flatMap((dto) => mapper.fromUpdateTo(dto, taskId))
         .flatMap(tasks.update)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
@@ -68,8 +67,9 @@ class ProjectTaskService {
   Future<Response> deleteTask(Request request, String taskId) async {
     return tasks
         .delete(taskId)
-        .match((left) => ResponseHelpers.fromError(left),
+        .flatMap(mapper.to)
-            (right) => Response.ok('Task deleted'))
+        .map((dto) => dto.toJson())
+        .toResponse()
         .run();
   }
 

backend-dart/lib/application/service/time_entry_service.dart

@@ -22,8 +22,8 @@ class TimeEntryService {
         .findAll()
         .flatMap(mapper.listTo)
         .map((entries) => entries.map((entry) => entry.toJson()).toList())
-        .match((left) => ResponseHelpers.fromError(left),
+        .map(jsonEncode)
-            (right) => Response.ok(jsonEncode(right)))
+        .toResponse()
         .run();
   }
 
@@ -32,35 +32,35 @@ class TimeEntryService {
     return entries
         .findById(entryId)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.post('/')
   Future<Response> createEntry(Request request) async {
     return requestToJson(request)
-        .flatMap((json) => validateJsonKeys(
+        .flatMap(
-            json, ['startTime', 'endTime', 'userId', 'projectId']))
+            validateJsonKeys(['startTime', 'endTime', 'userId', 'projectId']))
         .flatMap((json) => decodeJson(json, TimeEntryCreateDto.fromJson))
         .flatMap(mapper.fromCreateTo)
         .flatMap(entries.create)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.put('/<entryId>')
   Future<Response> updateEntry(Request request, String entryId) async {
     return requestToJson(request)
-        .flatMap((json) => validateJsonKeys(json, []))
+        .flatMap(validateJsonKeys([]))
         .flatMap((json) => decodeJson(json, TimeEntryUpdateDto.fromJson))
         .flatMap((dto) => mapper.fromUpdateTo(dto, entryId))
         .flatMap(entries.update)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
@@ -68,8 +68,8 @@ class TimeEntryService {
   Future<Response> deleteEntry(Request request, String entryId) async {
     return entries
         .delete(entryId)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => Response.ok('Entry deleted'))
+        .toResponse()
         .run();
   }
 

backend-dart/lib/application/service/user_service.dart

@@ -22,8 +22,8 @@ class UserService {
         .findAll()
         .flatMap(mapper.listTo)
         .map((users) => users.map((user) => user.toJson()).toList())
-        .match((left) => ResponseHelpers.fromError(left),
+        .map(jsonEncode)
-            (right) => Response.ok(jsonEncode(right)))
+        .toResponse()
         .run();
   }
 
@@ -32,35 +32,34 @@ class UserService {
     return users
         .findById(userId)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.post('/')
   Future<Response> createUser(Request request) async {
     return requestToJson(request)
-        .flatMap(
+        .flatMap(validateJsonKeys(['name', 'email', 'password']))
-            (json) => validateJsonKeys(json, ['name', 'email', 'password']))
         .flatMap((json) => decodeJson(json, UserCreateDto.fromJson))
         .flatMap(mapper.fromCreateTo)
         .flatMap(users.create)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
   @Route.put('/<userId>')
   Future<Response> updateUser(Request request, String userId) async {
     return requestToJson(request)
-        .flatMap((json) => validateJsonKeys(json, []))
+        .flatMap(validateJsonKeys([]))
         .flatMap((json) => decodeJson(json, UserUpdateDto.fromJson))
         .flatMap((dto) => mapper.fromUpdateTo(dto, userId))
         .flatMap(users.update)
         .flatMap(mapper.to)
-        .match((left) => ResponseHelpers.fromError(left),
+        .map((dto) => dto.toJson())
-            (right) => ResponseHelpers.jsonOk(right.toJson()))
+        .toResponse()
         .run();
   }
 
@@ -68,8 +67,9 @@ class UserService {
   Future<Response> deleteUser(Request request, String userId) async {
     return users
         .delete(userId)
-        .match((left) => ResponseHelpers.fromError(left),
+        .flatMap(mapper.to)
-            (right) => Response.ok('user deleted'))
+        .map((dto) => dto.toJson())
+        .toResponse()
         .run();
   }
 

backend-dart/lib/common/response_helpers.dart

@@ -1,8 +1,24 @@
 import 'dart:convert';
 import 'package:backend_dart/domain/errors/error_code.dart';
 import 'package:backend_dart/domain/interface/error.dart';
+import 'package:fpdart/fpdart.dart';
 import 'package:shelf/shelf.dart';
 
+extension TaskEitherResponseExtensions
+    on TaskEither<IError, Map<String, dynamic>> {
+  Task<Response> toResponse() => match(
+        (left) => ResponseHelpers.fromError(left),
+        (right) => ResponseHelpers.jsonOk(right),
+      );
+}
+
+extension TaskEitherResponseExtensionsFromString on TaskEither<IError, String> {
+  Task<Response> toResponse() => match(
+        (left) => ResponseHelpers.fromError(left),
+        (right) => Response.ok(right),
+      );
+}
+
 class ResponseHelpers {
   /// Sendet eine JSON-Antwort mit einem 200-Statuscode
   static Response jsonOk(Map<String, dynamic> data) {

backend-dart/lib/common/validation.dart

@@ -1,22 +1,18 @@
 import 'package:backend_dart/domain/errors/app_error.dart';
-import 'package:backend_dart/domain/interface/error.dart';
 import 'package:fpdart/fpdart.dart';
 
-TaskEither<IError, Map<String, dynamic>> validateJsonKeys(
+TaskEither<AppError, Map<String, dynamic>> Function(Map<String, dynamic>)
-    Map<String, dynamic> json, List<String> requiredKeys) {
+    validateJsonKeys(List<String> requiredKeys) {
-  return TaskEither.tryCatch(
+  return (json) {
-    () async {
     final missingKeys =
         requiredKeys.where((key) => !json.containsKey(key)).toList();
 
     if (missingKeys.isNotEmpty) {
-        throw Exception('Missing required keys: ${missingKeys.join(', ')}');
+      return TaskEither.left(AppError.validationError(
+        message: 'Missing required keys: ${missingKeys.join(', ')}',
+      ));
     }
 
-      return json;
+    return TaskEither.right(json);
-    },
+  };
-    (error, _) => AppError.validationError(
-      message: 'Failed to validate JSON keys: ${error.toString()}',
-    ),
-  );
 }

backend-dart/lib/domain/data/user_data_source.dart

@@ -11,7 +11,7 @@ abstract class UserDataSource {
 
   TaskEither<IError, User> update(UserUpdate user);
 
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, User> delete(String id);
 
   TaskEither<IError, List<User>> findAll();
 

backend-dart/lib/domain/repository/project_repository.dart

@@ -13,7 +13,7 @@ abstract class ProjectRepository {
   TaskEither<IError, Project> update(ProjectUpdate project);
 
   /// Deletes a project by its unique ID.
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, Project> delete(String id);
 
   /// Finds all projects.
   TaskEither<IError, List<Project>> findAll();

backend-dart/lib/domain/repository/project_task_repository.dart

@@ -16,7 +16,7 @@ abstract class ProjectTaskRepository {
   TaskEither<IError, ProjectTask> update(ProjectTaskUpdate task);
 
   /// Deletes a project task by its unique ID.
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, ProjectTask> delete(String id);
 
   /// Finds all project tasks.
   TaskEither<IError, List<ProjectTask>> findAll();

backend-dart/lib/domain/repository/time_entry_repository.dart

@@ -19,7 +19,7 @@ abstract class TimeEntryRepository {
   TaskEither<IError, TimeEntry> update(TimeEntryUpdate timeEntry);
 
   /// Deletes a time entry by its unique ID.
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, TimeEntry> delete(String id);
 
   /// Finds all time entries.
   TaskEither<IError, List<TimeEntry>> findAll();

backend-dart/lib/domain/repository/user_repository.dart

@@ -11,7 +11,7 @@ abstract class UserRepository {
 
   TaskEither<IError, User> update(UserUpdate user);
 
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, User> delete(String id);
 
   TaskEither<IError, List<User>> findAll();
 }

backend-dart/lib/infrastructure/persistence/prisma_user_data_source.dart

@@ -45,9 +45,13 @@ class PrismaUserDataSource implements UserDataSource {
         message: 'Failed to find user by email: ${error.toString()}',
       ),
     )
-        .flatMap(errorOnNull(AppError.notFound(
+        .flatMap(
+          errorOnNull(
+            AppError.notFound(
               'User with email $email found',
-        )))
+            ),
+          ),
+        )
         .flatMap(mapper.from);
   }
 
@@ -63,9 +67,13 @@ class PrismaUserDataSource implements UserDataSource {
         message: 'Failed to find user by ID: ${error.toString()}',
       ),
     )
-        .flatMap(errorOnNull(AppError.notFound(
+        .flatMap(
+          errorOnNull(
+            AppError.notFound(
               "User with id $id not found",
-        )))
+            ),
+          ),
+        )
         .flatMap(mapper.from);
   }
 
@@ -104,15 +112,24 @@ class PrismaUserDataSource implements UserDataSource {
   }
 
   @override
-  TaskEither<IError, void> delete(String id) {
+  TaskEither<IError, User> delete(String id) {
-    return TaskEither.tryCatch(
+    return TaskEither<IError, UserDbo?>.tryCatch(
       () async {
-        await prisma.userDbo.delete(where: UserDboWhereUniqueInput(id: id));
+        return await prisma.userDbo
+            .delete(where: UserDboWhereUniqueInput(id: id));
       },
       (error, _) => AppError.databaseError(
         message: 'Failed to delete user: ${error.toString()}',
       ),
-    );
+    )
+        .flatMap(
+          errorOnNull(
+            AppError.notFound(
+              'User not found',
+            ),
+          ),
+        )
+        .flatMap(mapper.from);
   }
 
   @override