Add validation to RealmCreate

IdentityShroud.Api/Apis/RealmApi.cs

@@ -1,3 +1,5 @@
+using FluentResults;
+using IdentityShroud.Api.Validation;
 using IdentityShroud.Core.Messages;
 using IdentityShroud.Core.Messages.Realm;
 using IdentityShroud.Core.Services;
@@ -6,23 +8,36 @@ using Microsoft.AspNetCore.Mvc;
 
 namespace IdentityShroud.Api;
 
-public static class RealmController
+public static class RealmApi
 {
     public static void MapRealmEndpoints(this IEndpointRouteBuilder app)
     {
-        var realm = app.MapGroup("/realms/{slug}");
+        var realmsGroup = app.MapGroup("/realms");
+        realmsGroup.MapPost("", RealmCreate)
+            .Validate<RealmCreateRequest>() 
+            .WithName("Create Realm")
+            .Produces(StatusCodes.Status201Created);
         
-        realm.MapGet("", GetRoot);
-        realm.MapPost("", (RealmCreateRequest request, [FromServices] RealmService service) =>
-            service.Create(request))
-            .WithName("Create Realm");
-        realm.MapGet(".well-known/openid-configuration", GetOpenIdConfiguration);
+        var realmSlugGroup = app.MapGroup("{slug}");
+        realmSlugGroup.MapGet("", GetRealmInfo);
+        realmSlugGroup.MapGet(".well-known/openid-configuration", GetOpenIdConfiguration);
 
-        var openidConnect = realm.MapGroup("openid-connect");
+        var openidConnect = realmSlugGroup.MapGroup("openid-connect");
         openidConnect.MapPost("auth", OpenIdConnectAuth);
         openidConnect.MapPost("token", OpenIdConnectToken);
         openidConnect.MapGet("jwks", OpenIdConnectJwks);
     }
+    
+    private static async Task<Results<Created<RealmCreateResponse>, InternalServerError>> 
+        RealmCreate(RealmCreateRequest request, [FromServices] IRealmService service)
+    {
+        var response = await service.Create(request);
+        if (response.IsSuccess)
+            return TypedResults.Created($"/realms/{response.Value.Slug}", response.Value);
+                    
+        // TODO make helper to convert failure response to a proper HTTP result.
+        return TypedResults.InternalServerError();
+    }
 
     private static Task OpenIdConnectJwks(HttpContext context)
     {
@@ -57,7 +72,7 @@ public static class RealmController
         }, AppJsonSerializerContext.Default.OpenIdConfiguration);
     }
 
-    private static string GetRoot()
+    private static string GetRealmInfo()
     {
         return "Hello World!";
         

IdentityShroud.Api/IdentityShroud.Api.csproj

@@ -10,7 +10,12 @@
         <UserSecretsId>6b8ef434-0577-4a3c-8749-6b547d7787c5</UserSecretsId>
     </PropertyGroup>
 
+    <PropertyGroup>
+        <PreserveCompilationContext>true</PreserveCompilationContext>
+    </PropertyGroup>    
+
     <ItemGroup>
+        <PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="12.1.1" />
         <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.0"/>
         <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="10.0.2" />
         <PackageReference Include="Serilog" Version="4.3.0" />

IdentityShroud.Api/Program.cs

@@ -1,10 +1,13 @@
+using FluentValidation;
 using IdentityShroud.Api;
+using IdentityShroud.Api.Validation;
 using IdentityShroud.Core;
 using IdentityShroud.Core.Contracts;
 using IdentityShroud.Core.Security;
 using Serilog;
 using Serilog.Formatting.Json;
 
+
 // Initial logging until we can set it up from Configuration
 Log.Logger = new LoggerConfiguration()
     .Enrich.FromLogContext()
@@ -34,6 +37,8 @@ void ConfigureBuilder(WebApplicationBuilder builder)
     services.AddOptions<DbConfiguration>().Bind(configuration.GetSection("db"));
     services.AddSingleton<ISecretProvider, ConfigurationSecretProvider>();
     
+    services.AddValidatorsFromAssemblyContaining<RealmCreateRequestValidator>();    
+    
     builder.Host.UseSerilog((context, services, configuration) => configuration
         .Enrich.FromLogContext()
         //.Enrich.With<UserEnricher>()
@@ -51,3 +56,5 @@ void ConfigureApplication(WebApplication app)
     // app.UseRouting();
     // app.MapControllers();
 }
+
+public partial class Program { }

IdentityShroud.Api/Validation/EndpointRouteBuilderExtensions.cs

@@ -0,0 +1,7 @@
+namespace IdentityShroud.Api.Validation;
+
+public static class EndpointRouteBuilderExtensions
+{
+    public static RouteHandlerBuilder Validate<TDto>(this RouteHandlerBuilder builder) where TDto : class
+        => builder.AddEndpointFilter<ValidateFilter<TDto>>();    
+}

IdentityShroud.Api/Validation/RealmCreateRequestValidator.cs

@@ -0,0 +1,19 @@
+using FluentValidation;
+using IdentityShroud.Core.Messages.Realm;
+
+namespace IdentityShroud.Api.Validation;
+
+public class RealmCreateRequestValidator : AbstractValidator<RealmCreateRequest>
+{
+    private const string SlugPattern = @"^(?=.{1,40}$)[a-z0-9]+(?:-[a-z0-9]+)*$";
+    
+    public RealmCreateRequestValidator()
+    {
+        RuleFor(x => x.Id)
+            .NotEqual(Guid.Empty).When(x => x.Id.HasValue);
+        RuleFor(x => x.Slug)
+            .Matches(SlugPattern).Unless(x => x.Slug is null);
+        RuleFor(x => x.Name)
+            .NotNull().Length(1, 255);
+    }
+}

IdentityShroud.Api/Validation/ValidateFilter.cs

@@ -0,0 +1,33 @@
+using FluentValidation;
+
+namespace IdentityShroud.Api.Validation;
+
+public class ValidateFilter<T> : IEndpointFilter where T : class
+{
+    public async ValueTask<object?> InvokeAsync(
+        EndpointFilterInvocationContext context,
+        EndpointFilterDelegate next)
+    {
+        // Grab the deserialized argument (the DTO) from the context.
+        // The order of arguments matches the order of parameters in the endpoint delegate.
+        var dto = context.Arguments
+            .FirstOrDefault(arg => arg is T) as T;
+
+        if (dto == null)
+            return Results.BadRequest("Unable to read request body.");
+
+        // Resolve the matching validator from DI.
+        var validator = context.HttpContext.RequestServices
+            .GetService<IValidator<T>>();
+
+        if (validator != null)
+        {
+            var validationResult = await validator.ValidateAsync(dto);
+            if (!validationResult.IsValid)
+                return Results.ValidationProblem(validationResult.ToDictionary());
+        }
+
+        // Validation passed – continue to the actual handler.
+        return await next(context);
+    }
+}