ResultsKit 1.0.2

ResultsKit

ResultsKit provides a simple result pattern for application code.

ResultsKit.Http maps those results to ASP.NET Core HTTP responses.

ResultsKit

Use Result when an operation only needs success or failure.

using ResultsKit;

public class UserService
{
    public Result DeleteUser(int id)
    {
        var exists = id > 0;
        if (!exists)
        {
            return new NotFoundError("user", id);
        }

        return Result.Ok();
    }
}

Use Result<T> when an operation returns data on success.

using ResultsKit;

public class UserService
{
    public Result<UserDto> GetUser(int id)
    {
        if (id <= 0)
        {
            return new ValidationError(["A valid user id is required."]);
        }

        if (id == 404)
        {
            return new NotFoundError("user", id);
        }

        return new UserDto(id, "Alex");
    }
}

public record UserDto(int Id, string Name);

Available error types:

• Error(code, message) for a custom failure
• NotFoundError(resource, reference) when a resource does not exist
• ConflictError(resource, reference, conflictingReference) when a request conflicts with an existing resource
• UnauthorizedError(action) when the caller is not allowed to perform an action
• ValidationError(messages) when validation fails

You can also create results explicitly:

using ResultsKit;

var success = Result.Ok();
var successWithValue = Result.OkResult(new UserDto(1, "Alex"));
var failure = Result.Fail(new Error("user_disabled", "The user is disabled."));
var partial = Result.Partial(new Error("warning", "The operation completed with warnings."));

ResultsKit.Http

Use ResultsKit.Http.Process to translate a Result or Result<T> into an HTTP response.

Minimal APIs

using ResultsKit.Http;

app.MapGet("/users/{id:int}", (int id, UserService service) =>
{
    var result = service.GetUser(id);
    return Process.ApiResult(result);
});

ApiResult(...) returns:

• 200 OK for successful results
• 400 Bad Request for generic and validation failures
• 401 Unauthorized for UnauthorizedError
• 404 Not Found for NotFoundError
• 409 Conflict for ConflictError

Error responses are returned as problem details payloads with neutral extension fields such as resource, reference, conflictingReference, messages, and action.

MVC / Controllers

using Microsoft.AspNetCore.Mvc;
using ResultsKit.Http;

[ApiController]
[Route("users")]
public class UsersController : ControllerBase
{
    [HttpGet("{id:int}")]
    public ActionResult<UserDto> Get(int id, [FromServices] UserService service)
    {
        var result = service.GetUser(id);
        return Process.MvcResult(result);
    }
}

MvcResult(...) applies the same status-code mapping and returns ASP.NET Core ActionResult / ActionResult<T> values.

Typical Pattern

Keep business logic in your service layer and return Result or Result<T> there.

using ResultsKit;

public class OrderService
{
    public Result<OrderDto> CreateOrder(CreateOrderRequest request)
    {
        if (string.IsNullOrWhiteSpace(request.CustomerCode))
        {
            return new ValidationError(["Customer code is required."]);
        }

        if (request.CustomerCode == "blocked")
        {
            return new UnauthorizedError("create-order");
        }

        return new OrderDto(123, request.CustomerCode);
    }
}

public record CreateOrderRequest(string CustomerCode);
public record OrderDto(int Id, string CustomerCode);

Then translate that result at the API boundary with Process.ApiResult(...) or Process.MvcResult(...).