Knight.Response.AspNetCore 1.0.2

Knight.Response.AspNetCore

ASP.NET Core integration for [Knight.Response]. It converts Result / Result<T> to HTTP responses, supports RFC7807 ProblemDetails (including validation errors), and provides an exception middleware for consistent error payloads.

NuGet packages you’ll typically use:

• Knight.Response – core result types and extensions
• Knight.Response.AspNetCore – this HTTP integration layer

Install

dotnet add package Knight.Response.AspNetCore

Quick start

1) Register in DI

// Program.cs
using Knight.Response.AspNetCore.Extensions;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

// Add Knight.Response HTTP integration (optional inline configuration)
builder.Services.AddKnightResponse(options =>
{
    // Defaults shown; override as needed
    options.IncludeFullResultPayload    = true;
    options.UseProblemDetails           = false;
    options.UseValidationProblemDetails = false;
    options.IncludeExceptionDetails     = false; // keep false in production

    // Inline override (not common; prefer the typed overload below)
    options.ValidationMapper = new MyValidationErrorMapper();
});

// Option A: register a custom validation mapper separately
builder.Services.AddScoped<IValidationErrorMapper, MyValidationErrorMapper>();

// Option B: use the typed overload
builder.Services.AddKnightResponse<MyValidationErrorMapper>(options =>
{
    options.UseValidationProblemDetails = true;
});

2) Add the exception middleware (optional)

var app = builder.Build();

app.UseKnightResponseExceptionMiddleware(); // must be registered before endpoints

app.MapGet("/", () => "OK");
app.Run();

The middleware catches unhandled exceptions and returns a consistent payload (ProblemDetails or JSON), honoring your configured options.

Using results in endpoints and controllers

You can return a Result/Result<T> as an ASP.NET Core IResult via helpers or extensions.

Minimal APIs

using Knight.Response.AspNetCore.Extensions;
using Knight.Response.Factories;

// Example domain service
public interface IUserService
{
    Task<Result<UserDto>> GetByIdAsync(int id, CancellationToken ct);
}

public record UserDto(int Id, string Name);

// Minimal API endpoint
app.MapGet("/users/{id:int}", async (int id, HttpContext http, IUserService userService, CancellationToken ct) =>
{
    var result = await userService.GetByIdAsync(id, ct);

    // Converts Result<UserDto> → IResult (200 if success, 400/ProblemDetails otherwise)
    return result.ToIResult(http);
});

MVC Controllers

using Knight.Response.AspNetCore.Factories;
using Knight.Response.Core;
using Microsoft.AspNetCore.Mvc;

// Example DTOs
public record CreateUserRequest(string Name);
public record UserDto(int Id, string Name);

// Example domain service
public interface IUserService
{
    Task<Result<UserDto>> CreateAsync(CreateUserRequest request, CancellationToken ct);
    Task<Result<UserDto>> GetByIdAsync(int id, CancellationToken ct);
}

[ApiController]
[Route("api/users")]
public class UsersController : ControllerBase
{
    private readonly IUserService _userService;

    public UsersController(IUserService userService)
    {
        _userService = userService;
    }

    [HttpPost]
    public async Task<IResult> Create([FromBody] CreateUserRequest request, CancellationToken ct)
    {
        var result = await _userService.CreateAsync(request, ct);

        // Maps Result<UserDto> → 201 Created or error
        return ApiResults.Created(result, HttpContext, location: result.IsSuccess 
            ? $"/api/users/{result.Value.Id}" 
            : null);
    }

    [HttpGet("{id:int}")]
    public async Task<IResult> Get(int id, CancellationToken ct)
    {
        var result = await _userService.GetByIdAsync(id, ct);

        // Maps Result<UserDto> → 200 OK if found, otherwise 400/ProblemDetails
        return ApiResults.Ok(result, HttpContext);
    }
}

What gets returned

Behavior depends on KnightResponseOptions:

• Success (2xx):

  • IncludeFullResultPayload = true Returns the full Result/Result<T> as JSON (201 Created uses the body and optional Location header).
  • IncludeFullResultPayload = false Returns Value (for Result<T>) or an empty 2xx with the chosen status.

• Failure (non-2xx):

  • UseProblemDetails = true Returns RFC7807 ProblemDetails. If UseValidationProblemDetails = true and the validation mapper produces field errors, returns ValidationProblemDetails.
  • UseProblemDetails = false Returns a simple JSON array of messages with the chosen status.

• Status codes: Determined by StatusCodeResolver (defaults shown below).

Default status code mapping

You can override this mapping via KnightResponseOptions.StatusCodeResolver.

API surface

Result → IResult conversion

Use either the extensions or the factory:

• Extensions (Minimal API friendly)

  • Result.ToIResult(HttpContext? http = null)
  • Result<T>.ToIResult(HttpContext? http = null)

• Factory methods (works everywhere)

  • ApiResults.Ok(Result|Result<T>, HttpContext? http = null)
  • ApiResults.Created(Result|Result<T>, HttpContext? http = null, string? location = null)
  • ApiResults.Accepted(Result|Result<T>, HttpContext? http = null, string? location = null)
  • ApiResults.NoContent(Result, HttpContext? http = null)
  • ApiResults.BadRequest(Result, HttpContext? http = null)
  • ApiResults.NotFound(Result, HttpContext? http = null)
  • ApiResults.Conflict(Result, HttpContext? http = null)
  • ApiResults.Unauthorized(), ApiResults.Forbidden()

All methods consult DI for KnightResponseOptions if HttpContext is provided; otherwise defaults are used.

Options

Options type comes from

public sealed class KnightResponseOptions
    : KnightResponseBaseOptions<ProblemDetails, ValidationProblemDetails>
{
    // Same core properties:
    // - IncludeFullResultPayload
    // - UseProblemDetails
    // - UseValidationProblemDetails
    // - IncludeExceptionDetails
    // - StatusCodeResolver
    // - ValidationMapper (default: DefaultValidationErrorMapper from Abstractions)
    // - ProblemDetailsBuilder, ValidationBuilder
}

Register and customize:

builder.Services.AddKnightResponse(options =>
{
    options.IncludeFullResultPayload    = true;
    options.UseProblemDetails           = true;
    options.UseValidationProblemDetails = true;

    options.StatusCodeResolver = status => status switch
    {
        Status.Failed    => StatusCodes.Status400BadRequest,
        Status.Cancelled => StatusCodes.Status409Conflict,
        Status.Error     => StatusCodes.Status500InternalServerError,
        _                => StatusCodes.Status400BadRequest
    };

    // Optional customization of ProblemDetails payload
    options.ProblemDetailsBuilder = (http, result, pd) =>
    {
        pd.Extensions["svcStatus"] = result.Status.ToString();
    };
});

Validation mapping

By default, validation messages are projected to a simple Dictionary<string, string[]> using DefaultValidationErrorMapper. Plug in your own:

builder.Services.AddKnightResponse();
builder.Services.AddScoped<IValidationErrorMapper, MyCustomMapper>();

If the mapper returns one or more field errors and UseValidationProblemDetails is enabled, responses use ValidationProblemDetails. Otherwise, they fall back to standard ProblemDetails.

Exception middleware

UseKnightResponseExceptionMiddleware() wraps the pipeline and converts unhandled exceptions to a consistent error response:

• Logs exceptions via ILogger<KnightResponseExceptionMiddleware>
• Honors UseProblemDetails and IncludeExceptionDetails
• Uses StatusCodeResolver to select the HTTP status (default 500)

Register early in the pipeline (after logging, before endpoints):

app.UseKnightResponseExceptionMiddleware();

Notes

• Works with both Minimal APIs and MVC controllers. IResult is first-class in .NET 8 and can be returned from controllers as well.
• If you prefer IActionResult, you can wrap IResult via Results.Extensions.ToActionResult() in .NET 8+, but this library focuses on IResult for modern apps.
• For consistent payloads across your app, prefer returning Result/Result<T> and translating via these helpers everywhere.

License

This project is licensed under the MIT License.

Contributing

Contributions are welcome! Please read CONTRIBUTING.md.