Skip to main content

ASP.NET Core Integration

UnambitiousFx.Functional.AspNetCore (v2.0.0) turns the functional types from UnambitiousFx.Functional into HTTP responses. Keep your domain and application services returning Result, Result<T>, and Maybe<T>, then adapt the outcome to HTTP at the API boundary — for both Minimal APIs (IResult) and MVC controllers (IActionResult).

The conversion is driven by fluent builders. A single failure-to-status mapper (IFailureHttpMapper) centralizes how each failure type becomes an HTTP status code and body, so transport concerns stay out of your business logic.

Install​

dotnet add package UnambitiousFx.Functional.AspNetCore

How it works​

  • Success branches are mapped to a status code (200/201/202/204) with the value serialized as the body.
  • Failure branches are passed to the configured IFailureHttpMapper, which produces a status code and (by default) an RFC ProblemDetails body.

Registration (optional)​

The builders work with no setup at all — they fall back to DefaultFailureHttpMapper when you don't pass a mapper. To register a shared mapper (and custom mappings) in DI, call AddResultHttp:

using UnambitiousFx.Functional.AspNetCore;

builder.Services.AddResultHttp();

AddResultHttp registers the resolved IFailureHttpMapper and a ResultHttpAdapterPolicy as singletons. Pass a configuration delegate to add custom mappings — see Custom Mappers. Inject the mapper into endpoints/controllers and pass it to the builder when you want DI-managed behavior:

app.MapGet("/users/{id:guid}", async (
    Guid id,
    IUserService service,
    IFailureHttpMapper mapper) =>
    await service.GetUserAsync(id).AsHttpBuilder(mapper));

Minimal API — quick look​

Namespace: UnambitiousFx.Functional.AspNetCore.Http

using UnambitiousFx.Functional.AspNetCore.Http;

// Result<T> → 200 OK with the value, failures mapped automatically
app.MapGet("/users/{id:guid}", async (Guid id, IUserService service) =>
    await service.GetUserAsync(id).AsHttpBuilder());

// Maybe<T> → 200 on Some, 404 on None
app.MapGet("/profiles/{id:guid}", async (Guid id, IProfileService service) =>
    await service.FindProfileAsync(id).AsHttpBuilder());

// 201 Created with a Location header
app.MapPost("/users", async (CreateUserRequest request, IUserService service) =>
    await service.CreateAsync(request)
                 .AsHttpBuilder()
                 .AsCreated(user => $"/users/{user.Id}"));

The builder is awaitable directly — await someResult.AsHttpBuilder() yields the IResult.

MVC — quick look​

Namespace: UnambitiousFx.Functional.AspNetCore.Mvc

using UnambitiousFx.Functional.AspNetCore.Mvc;

[ApiController]
[Route("api/users")]
public sealed class UsersController : ControllerBase
{
    [HttpGet("{id:guid}")]
    public async Task<IActionResult> Get(Guid id, [FromServices] IUserService service)
        => await service.GetUserAsync(id).AsActionResultBuilder();
}

Default failure mapping​

DefaultFailureHttpMapper maps the standard failure types from UnambitiousFx.Functional.Failures:

Failure typeHTTP statusBody
ValidationFailure400 Bad RequestProblemDetails
BadRequestFailure400 Bad RequestProblemDetails
NotFoundFailure404 Not FoundProblemDetails
UnauthorizedFailure401 UnauthorizedProblemDetails
UnauthenticatedFailure403 ForbiddenProblemDetails
ConflictFailure409 ConflictProblemDetails
ExceptionalFailure500 Internal Server ErrorProblemDetails
Any other failure500 Internal Server ErrorProblemDetails

:::note Naming vs. status The default mapper maps UnauthorizedFailure to 401 and UnauthenticatedFailure to 403. If your API contract expects the conventional 401/403 split, override these with a custom mapper. :::

Learn more​

  • HTTP Mapping (Minimal API) — the full builder API, status-code control, headers, Problem Details shape, and Minimal API patterns.
  • MVC Patterns — controller usage and IActionResult builders.
  • Custom Mappers — customize failure-to-status mapping and adapter policy.

See also​