Update exception handling (#146)

src/Core/API/API.Core/API.Core.csproj

@@ -18,7 +18,8 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\Domain\Domain.csproj" />
+    <ProjectReference Include="..\..\Domain.Entities\Domain.Entities.csproj" />
+    <ProjectReference Include="..\..\Domain.Exceptions\Domain.Exceptions.csproj" />
     <ProjectReference Include="..\..\Infrastructure\Infrastructure.Repository\Infrastructure.Repository.csproj" />
     <ProjectReference Include="..\..\Infrastructure\Infrastructure.Jwt\Infrastructure.Jwt.csproj" />
     <ProjectReference Include="..\..\Service\Service.Auth\Service.Auth.csproj" />

src/Core/API/API.Core/Controllers/AuthController.cs

@@ -44,13 +44,6 @@ namespace API.Core.Controllers
         public async Task<ActionResult> Login([FromBody] LoginRequest req)
         {
             var userAccount = await login.LoginAsync(req.Username, req.Password);
-            if (userAccount is null)
-            {
-                return Unauthorized(new ResponseBody
-                {
-                    Message = "Invalid username or password."
-                });
-            }
 
             UserDTO dto = new(userAccount.UserAccountId, userAccount.Username);
 

src/Core/API/API.Core/Controllers/UserController.cs

@@ -19,7 +19,6 @@ namespace API.Core.Controllers
         public async Task<ActionResult<UserAccount>> GetById(Guid id)
         {
             var user = await userService.GetByIdAsync(id);
-            if (user is null) return NotFound();
             return Ok(user);
         }
     }

src/Core/API/API.Core/Dockerfile

@@ -9,7 +9,8 @@ FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
 ARG BUILD_CONFIGURATION=Release
 WORKDIR /src
 COPY ["API/API.Core/API.Core.csproj", "API/API.Core/"]
-COPY ["Domain/Domain.csproj", "Domain/"]
+COPY ["Domain.Entities/Domain.Entities.csproj", "Domain.Entities/"]
+COPY ["Domain.Exceptions/Domain.Exceptions.csproj", "Domain.Exceptions/"]
 COPY ["Infrastructure/Infrastructure.Repository/Infrastructure.Repository.csproj", "Infrastructure/Infrastructure.Repository/"]
 COPY ["Infrastructure/Infrastructure.Jwt/Infrastructure.Jwt.csproj", "Infrastructure/Infrastructure.Jwt/"]
 COPY ["Infrastructure/Infrastructure.PasswordHashing/Infrastructure.PasswordHashing.csproj", "Infrastructure/Infrastructure.PasswordHashing/"]

src/Core/API/API.Core/GlobalException.cs

@@ -0,0 +1,84 @@
+// API.Core/Filters/GlobalExceptionFilter.cs
+
+using API.Core.Contracts.Common;
+using Domain.Exceptions;
+using FluentValidation;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+
+namespace API.Core;
+
+public class GlobalExceptionFilter(ILogger<GlobalExceptionFilter> logger) : IExceptionFilter
+{
+    public void OnException(ExceptionContext context)
+    {
+        logger.LogError(context.Exception, "Unhandled exception occurred");
+
+        switch (context.Exception)
+        {
+            case FluentValidation.ValidationException fluentValidationException:
+                var errors = fluentValidationException.Errors
+                    .GroupBy(e => e.PropertyName)
+                    .ToDictionary(
+                        g => g.Key,
+                        g => g.Select(e => e.ErrorMessage).ToArray()
+                    );
+
+                context.Result = new BadRequestObjectResult(new
+                {
+                    message = "Validation failed",
+                    errors
+                });
+                context.ExceptionHandled = true;
+                break;
+
+            case ConflictException ex:
+                context.Result = new ObjectResult(new ResponseBody { Message = ex.Message })
+                {
+                    StatusCode = 409
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case NotFoundException ex:
+                context.Result = new ObjectResult(new ResponseBody { Message = ex.Message })
+                {
+                    StatusCode = 404
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case UnauthorizedException ex:
+                context.Result = new ObjectResult(new ResponseBody { Message = ex.Message })
+                {
+                    StatusCode = 401
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case ForbiddenException ex:
+                context.Result = new ObjectResult(new ResponseBody { Message = ex.Message })
+                {
+                    StatusCode = 403
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case Domain.Exceptions.ValidationException ex:
+                context.Result = new ObjectResult(new ResponseBody { Message = ex.Message })
+                {
+                    StatusCode = 400
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            default:
+                context.Result = new ObjectResult(new ResponseBody { Message = "An unexpected error occurred" })
+                {
+                    StatusCode = 500
+                };
+                context.ExceptionHandled = true;
+                break;
+        }
+    }
+}

src/Core/API/API.Core/Middleware/ValidationExceptionHandlingMiddleware.cs

@@ -1,47 +0,0 @@
-using System.Net;
-using System.Text.Json;
-using API.Core.Contracts.Common;
-using FluentValidation;
-
-namespace API.Core.Middleware;
-
-public class ValidationExceptionHandlingMiddleware(RequestDelegate next)
-{
-   public async Task InvokeAsync(HttpContext context)
-   {
-      try
-      {
-         await next(context);
-      }
-      catch (ValidationException ex)
-      {
-         await HandleValidationExceptionAsync(context, ex);
-      }
-   }
-
-   private static Task HandleValidationExceptionAsync(HttpContext context, ValidationException exception)
-   {
-      context.Response.ContentType = "application/json";
-      context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
-
-      var errors = exception.Errors
-          .Select(e => e.ErrorMessage)
-          .ToList();
-
-      var message = errors.Count == 1
-          ? errors[0]
-          : "Validation failed. " + string.Join(" ", errors);
-
-      var response = new ResponseBody
-      {
-         Message = message
-      };
-
-      var jsonOptions = new JsonSerializerOptions
-      {
-         PropertyNamingPolicy = JsonNamingPolicy.CamelCase
-      };
-
-      return context.Response.WriteAsync(JsonSerializer.Serialize(response, jsonOptions));
-   }
-}

src/Core/API/API.Core/Program.cs

@@ -1,3 +1,5 @@
+using API.Core;
+using Domain.Exceptions;
 using FluentValidation;
 using FluentValidation.AspNetCore;
 using Infrastructure.Jwt;
@@ -6,34 +8,19 @@ using Infrastructure.Repository.Auth;
 using Infrastructure.Repository.Sql;
 using Infrastructure.Repository.UserAccount;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
 using Service.Auth.Auth;
 using Service.UserManagement.User;
-
+using API.Core.Contracts.Common;
 
 var builder = WebApplication.CreateBuilder(args);
 
-builder.Services.AddControllers()
+// Global Exception Filter
-    .ConfigureApiBehaviorOptions(options =>
+builder.Services.AddControllers(options =>
 {
-        options.InvalidModelStateResponseFactory = context =>
+    options.Filters.Add<GlobalExceptionFilter>();
-        {
-            var errors = context.ModelState.Values
-                .SelectMany(v => v.Errors)
-                .Select(e => e.ErrorMessage)
-                .ToList();
-
-            var message = errors.Count == 1
-                ? errors[0]
-                : string.Join(" ", errors);
-
-            var response = new
-            {
-                message
-            };
-
-            return new BadRequestObjectResult(response);
-        };
 });
+
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen();
 builder.Services.AddOpenApi();
@@ -67,6 +54,8 @@ builder.Services.AddScoped<IRegisterService, RegisterService>();
 builder.Services.AddScoped<ITokenInfrastructure, JwtInfrastructure>();
 builder.Services.AddScoped<IPasswordInfrastructure, Argon2Infrastructure>();
 
+// Register the exception filter
+builder.Services.AddScoped<GlobalExceptionFilter>();
 
 var app = builder.Build();
 
@@ -90,6 +79,3 @@ lifetime.ApplicationStopping.Register(() =>
 });
 
 app.Run();
-
-// Make Program class accessible to test projects
-public partial class Program { }

src/Core/API/API.Specs/Dockerfile

@@ -3,7 +3,8 @@ ARG BUILD_CONFIGURATION=Release
 WORKDIR /src
 COPY ["API/API.Core/API.Core.csproj", "API/API.Core/"]
 COPY ["API/API.Specs/API.Specs.csproj", "API/API.Specs/"]
-COPY ["Domain/Domain.csproj", "Domain/"]
+COPY ["Domain.Entities/Domain.Entities.csproj", "Domain.Entities/"]
+COPY ["Domain.Exceptions/Domain.Exceptions.csproj", "Domain.Exceptions/"]
 COPY ["Infrastructure/Infrastructure.Repository/Infrastructure.Repository.csproj", "Infrastructure/Infrastructure.Repository/"]
 COPY ["Infrastructure/Infrastructure.Jwt/Infrastructure.Jwt.csproj", "Infrastructure/Infrastructure.Jwt/"]
 COPY ["Infrastructure/Infrastructure.PasswordHashing/Infrastructure.PasswordHashing.csproj", "Infrastructure/Infrastructure.PasswordHashing/"]

src/Core/API/API.Specs/Features/Registration.feature

@@ -12,25 +12,19 @@ Feature: User Registration
     And the response JSON should have "message" equal "User registered successfully."
     And the response JSON should have an access token
 
-  @Ignore
   Scenario: Registration fails with existing username
     Given the API is running
-    And I have an existing account with username "existinguser"
     When I submit a registration request with values:
       | Username  | FirstName | LastName | Email               | DateOfBirth | Password   |
-      | existinguser | Existing  | User     | existing@example.com | 1990-01-01  | Password1! |
+      | test.user | Test      | User     | example@example.com | 2001-11-11  | Password1! |
     Then the response has HTTP status 409
-    And the response JSON should have "message" equal "Username already exists."
 
-  @Ignore
   Scenario: Registration fails with existing email
     Given the API is running
-    And I have an existing account with email "existing@example.com"
     When I submit a registration request with values:
       | Username | FirstName | LastName | Email                       | DateOfBirth | Password   |
-      | newuser  | New       | User     | existing@example.com | 1990-01-01  | Password1! |
+      | newuser  | New       | User     | test.user@thebiergarten.app | 1990-01-01  | Password1! |
     Then the response has HTTP status 409
-    And the response JSON should have "message" equal "Email already in use."
 
   Scenario: Registration fails with missing required fields
     Given the API is running

src/Core/API/API.Specs/Steps/AuthSteps.cs

@@ -201,18 +201,6 @@ public class AuthSteps(ScenarioContext scenario)
         scenario[ResponseBodyKey] = responseBody;
     }
 
-    [Given("I have an existing account with username {string}")]
-    public void GivenIHaveAnExistingAccountWithUsername(string username)
-    {
-
-    }
-
-    [Given("I have an existing account with email {string}")]
-    public void GivenIHaveAnExistingAccountWithEmail(string email)
-    {
-
-    }
-
     [When("I submit a registration request using a GET request")]
     public async Task WhenISubmitARegistrationRequestUsingAGetRequest()
     {

src/Core/Core.slnx

@@ -8,7 +8,8 @@
     <Project Path="Database/Database.Seed/Database.Seed.csproj" />
   </Folder>
   <Folder Name="/Domain/">
-    <Project Path="Domain/Domain.csproj" />
+    <Project Path="Domain.Entities\Domain.Entities.csproj" />
+    <Project Path="Domain.Exceptions/Domain.Exceptions.csproj" />
   </Folder>
   <Folder Name="/Infrastructure/">
     <Project Path="Infrastructure/Infrastructure.Jwt/Infrastructure.Jwt.csproj" />

src/Core/Database/Database.Seed/Database.Seed.csproj

@@ -18,7 +18,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\Domain\Domain.csproj" />
+    <ProjectReference Include="..\..\Domain.Entities\Domain.Entities.csproj" />
     <ProjectReference Include="..\..\Infrastructure\Infrastructure.Repository\Infrastructure.Repository.csproj" />
   </ItemGroup>
 </Project>

src/Core/Database/Database.Seed/UserSeeder.cs

@@ -124,6 +124,7 @@ internal class UserSeeder : ISeeder
         int createdCredentials = 0;
         int createdVerifications = 0;
 
+        // create a known user for testing purposes
         {
             const string firstName = "Test";
             const string lastName = "User";

src/Core/Domain.Exceptions/Domain.Exceptions.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+</Project>

src/Core/Domain.Exceptions/Exceptions.cs

@@ -0,0 +1,33 @@
+namespace Domain.Exceptions;
+
+/// <summary>
+/// Exception thrown when a resource conflict occurs (e.g., duplicate username, email already in use).
+/// Maps to HTTP 409 Conflict.
+/// </summary>
+public class ConflictException(string message) : Exception(message);
+
+/// <summary>
+/// Exception thrown when a requested resource is not found.
+/// Maps to HTTP 404 Not Found.
+/// </summary>
+public class NotFoundException(string message) : Exception(message);
+
+// Domain.Exceptions/UnauthorizedException.cs
+
+/// <summary>
+/// Exception thrown when authentication fails or is required.
+/// Maps to HTTP 401 Unauthorized.
+/// </summary>
+public class UnauthorizedException(string message) : Exception(message);
+
+/// <summary>
+/// Exception thrown when a user is authenticated but lacks permission to access a resource.
+/// Maps to HTTP 403 Forbidden.
+/// </summary>
+public class ForbiddenException(string message) : Exception(message);
+
+/// <summary>
+/// Exception thrown when business rule validation fails (distinct from FluentValidation).
+/// Maps to HTTP 400 Bad Request.
+/// </summary>
+public class ValidationException(string message) : Exception(message);

src/Core/Infrastructure/Infrastructure.Repository.Tests/Dockerfile

@@ -1,7 +1,8 @@
 FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
 ARG BUILD_CONFIGURATION=Release
 WORKDIR /src
-COPY ["Domain/Domain.csproj", "Domain/"]
+COPY ["Domain.Entities/Domain.Entities.csproj", "Domain.Entities/"]
+COPY ["Domain.Exceptions/Domain.Exceptions.csproj", "Domain.Exceptions/"]
 COPY ["Infrastructure/Infrastructure.Repository/Infrastructure.Repository.csproj", "Infrastructure/Infrastructure.Repository/"]
 COPY ["Infrastructure/Infrastructure.Repository.Tests/Infrastructure.Repository.Tests.csproj", "Infrastructure/Infrastructure.Repository.Tests/"]
 RUN dotnet restore "Infrastructure/Infrastructure.Repository.Tests/Infrastructure.Repository.Tests.csproj"

src/Core/Infrastructure/Infrastructure.Repository/Infrastructure.Repository.csproj

@@ -18,6 +18,6 @@
     />
   </ItemGroup>
   <ItemGroup>
-    <ProjectReference Include="..\..\Domain\Domain.csproj" />
+    <ProjectReference Include="..\..\Domain.Entities\Domain.Entities.csproj" />
   </ItemGroup>
 </Project>

src/Core/Service/Service.Auth/Auth/ILoginService.cs

@@ -5,5 +5,5 @@ namespace Service.Auth.Auth;
 
 public interface ILoginService
 {
-    Task<UserAccount?> LoginAsync(string username, string password);
+    Task<UserAccount> LoginAsync(string username, string password);
 }

src/Core/Service/Service.Auth/Auth/LoginService.cs

@@ -1,5 +1,6 @@
 using System.Threading.Tasks;
 using Domain.Entities;
+using Domain.Exceptions;
 using Infrastructure.PasswordHashing;
 using Infrastructure.Repository.Auth;
 
@@ -11,18 +12,24 @@ public class LoginService(
 ) : ILoginService
 {
 
-    public async Task<UserAccount?> LoginAsync(string username, string password)
+    public async Task<UserAccount> LoginAsync(string username, string password)
     {
         // Attempt lookup by username
         var user = await authRepo.GetUserByUsernameAsync(username);
 
         // the user was not found
-        if (user is null) return null;
+        if (user is null)
+            throw new UnauthorizedException("Invalid username or password.");
 
         // @todo handle expired passwords
         var activeCred = await authRepo.GetActiveCredentialByUserAccountIdAsync(user.UserAccountId);
 
-        if (activeCred is null) return null;
+        if (activeCred is null)
-        return !passwordInfrastructure.Verify(password, activeCred.Hash) ? null : user;
+            throw new UnauthorizedException("Invalid username or password.");
+
+        if (!passwordInfrastructure.Verify(password, activeCred.Hash))
+            throw new UnauthorizedException("Invalid username or password.");
+
+        return user;
     }
 }

src/Core/Service/Service.Auth/Auth/RegisterService.cs

@@ -1,5 +1,6 @@
 using System.Threading.Tasks;
 using Domain.Entities;
+using Domain.Exceptions;
 using Infrastructure.PasswordHashing;
 using Infrastructure.Repository.Auth;
 
@@ -13,12 +14,16 @@ public class RegisterService(
     public async Task<UserAccount> RegisterAsync(UserAccount userAccount, string password)
     {
         // Check if user already exists
-        var user = await authRepo.GetUserByUsernameAsync(userAccount.Username);
+        var existingUsername = await authRepo.GetUserByUsernameAsync(userAccount.Username);
-        if (user is not null)
+        var existingEmail = await authRepo.GetUserByEmailAsync(userAccount.Email);
+
+        if (existingUsername != null || existingEmail != null)
         {
-            return null!;
+            throw new ConflictException("Username or email already exists");
         }
 
+
+
         // password hashing
         var hashed = passwordInfrastructure.Hash(password);
 

src/Core/Service/Service.Auth/Service.Auth.csproj

@@ -10,8 +10,10 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\Domain\Domain.csproj" />
+    <ProjectReference Include="..\..\Domain.Entities\Domain.Entities.csproj" />
-    <ProjectReference Include="..\..\Infrastructure\Infrastructure.Repository\Infrastructure.Repository.csproj" />
+    <ProjectReference Include="..\..\Domain.Exceptions\Domain.Exceptions.csproj" />
+    <ProjectReference
+      Include="..\..\Infrastructure\Infrastructure.Repository\Infrastructure.Repository.csproj" />
     <ProjectReference
       Include="..\..\Infrastructure\Infrastructure.PasswordHashing\Infrastructure.PasswordHashing.csproj" />
   </ItemGroup>

src/Core/Service/Service.UserManagement/Service.UserManagement.csproj

@@ -7,7 +7,9 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <ProjectReference Include="..\..\Infrastructure\Infrastructure.Repository\Infrastructure.Repository.csproj" />
+        <ProjectReference Include="..\..\Domain.Exceptions\Domain.Exceptions.csproj" />
+        <ProjectReference
+            Include="..\..\Infrastructure\Infrastructure.Repository\Infrastructure.Repository.csproj" />
     </ItemGroup>
 
 </Project>

src/Core/Service/Service.UserManagement/User/IUserService.cs

@@ -5,7 +5,7 @@ namespace Service.UserManagement.User;
 public interface IUserService
 {
     Task<IEnumerable<UserAccount>> GetAllAsync(int? limit = null, int? offset = null);
-    Task<UserAccount?> GetByIdAsync(Guid id);
+    Task<UserAccount> GetByIdAsync(Guid id);
 
     Task UpdateAsync(UserAccount userAccount);
 }

src/Core/Service/Service.UserManagement/User/UserService.cs

@@ -1,4 +1,5 @@
 using Domain.Entities;
+using Domain.Exceptions;
 using Infrastructure.Repository.UserAccount;
 
 namespace Service.UserManagement.User;
@@ -10,9 +11,12 @@ public class UserService(IUserAccountRepository repository) : IUserService
         return await repository.GetAllAsync(limit, offset);
     }
 
-    public async Task<UserAccount?> GetByIdAsync(Guid id)
+    public async Task<UserAccount> GetByIdAsync(Guid id)
     {
-        return await repository.GetByIdAsync(id);
+        var user = await repository.GetByIdAsync(id);
+        if (user is null)
+            throw new NotFoundException($"User with ID {id} not found");
+        return user;
     }
 
     public async Task UpdateAsync(UserAccount userAccount)