Hesham.ResultPattern.Extension.MinimalAPI 1.1.2

ResultPattern.Extension.MinimalAPI

Minimal API response helpers for ResultPattern.
Maps Result<TValue> and List<Error> directly to standards-compliant HTTP Problem Details responses — with zero boilerplate.

📦 Installation

dotnet add package ResultPattern.Extension.MinimalAPI

Requires: ResultPattern core package.

🚀 Quick Start

1. Register Services

builder.Services.AddResponseHelper();

2. Inject and Use in Endpoints

app.MapGet("/basket/{userName}", async (
    string userName,
    ISender sender,
    ResponseHelper responseHelper,
    CancellationToken ct) =>
{
    var query = new GetBasketQuery(userName);

    Result<GetBasketResult> result = await sender.Send(query, ct);

    return result.Match(
        val => Results.Ok(val.Adapt<GetBasketResponse>()),
        responseHelper.ToProblemResult);
})

ResponseHelper is registered as a scoped service. Inject it directly into your endpoint delegate and pass responseHelper.ToProblemResult as the error branch of Match — no extra wiring needed.

ResponseHelper

The core service exposed by this package. It takes a List<Error> and produces an IResult shaped as an RFC 7807 Problem Details response.

ToProblemResult(List<Error> errors)

The main entry point. Inspects the error list and delegates to the appropriate response builder:

Response Shapes

Validation Errors — 422 Unprocessable Entity

Triggered when all errors in the list carry a 422 status code (i.e. all created via Error.Validation(...)).
All descriptions are collected, deduplicated, and returned under a single "errors" key.

{
  "title": "Validation",
  "status": 422,
  "detail": "One or more validation errors occurred.",
  "errors": {
    "errors": [
      "Name cannot be null or empty.",
      "Name cannot be less than 3 characters.",
      "Invalid email address."
    ]
  }
}

In Development, each error's full stack trace is appended under extensions.stackTraces:

{
  "title": "Validation",
  "status": 422,
  "detail": "One or more validation errors occurred.",
  "errors": {
    "errors": [
      "Name cannot be null or empty.",
      "Invalid email address."
    ]
  },
  "extensions": {
    "stackTraces": [
      {
        "description": "Name cannot be null or empty.",
        "stackTrace": {
          "memberName": "Create",
          "fileName": "User.cs",
          "lineNumber": 12
        }
      },
      {
        "description": "Invalid email address.",
        "stackTrace": {
          "memberName": "Create",
          "fileName": "User.cs",
          "lineNumber": 18
        }
      }
    ]
  }
}

Single / Mixed Errors — Problem Details

Triggered when errors are not all 422 — e.g. 404, 403, 409, or 500.
The first error in the list drives the response status and title.

{
  "title": "NotFound",
  "status": 404,
  "detail": "Restaurant with id '5' not found."
}

In Development, the error's stack trace is appended under extensions.stackTrace:

{
  "title": "NotFound",
  "status": 404,
  "detail": "Restaurant with id '5' not found.",
  "extensions": {
    "stackTrace": {
      "memberName": "Handle",
      "fileName": "DeleteRestaurantCommandHandler.cs",
      "lineNumber": 14
    }
  }
}

Stack traces are never exposed in Production. The IHostEnvironment is checked internally — no configuration required.

Environment-Aware Diagnostics

ResponseHelper automatically adjusts its response detail based on the current environment:

Full Endpoint Example

A complete delete endpoint using ResultPattern and ResponseHelper together:

app.MapDelete("/restaurants/{id}", async (
    Guid id,
    ISender sender,
    ResponseHelper responseHelper,
    CancellationToken ct) =>
{
    var command = new DeleteRestaurantCommand(id);

    Result<Success> result = await sender.Send(command, ct);

    return result.Match(
        _ => Results.NoContent(),
        responseHelper.ToProblemResult);
})
.RequireAuthorization();

app.MapPost("/users", async (
    CreateUserRequest request,
    ISender sender,
    ResponseHelper responseHelper,
    CancellationToken ct) =>
{
    var command = new CreateUserCommand(request.Name, request.Email);

    Result<UserResponse> result = await sender.Send(command, ct);

    return result.Match(
        user => Results.Created($"/users/{user.Id}", user),
        responseHelper.ToProblemResult);
})

MVC & Web API vs Minimal API

Both extension packages expose an identical ResponseHelper API surface and produce the same Problem Details response shapes. Choose based on how your application is structured:

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