CoreMesh.Result 0.3.1

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CoreMesh.Result

CoreMesh.Result provides a strongly-typed result pattern for ASP.NET Core applications, with built-in HTTP response mapping via Minimal API TypedResults.

It allows you to:

1. Return operation outcomes as Result / Result<T> from service or domain layers
2. Carry HTTP semantics (Ok, NotFound, Invalid, etc.) without depending on ASP.NET Core in your business logic
3. Convert results to IResult at the API boundary with a single call

Features

• Result / Result<T>: non-generic and generic result types
• Error: machine-readable code + human-readable description
• ResultStatus: enum encoding the HTTP outcome (Ok, Created, NotFound, Forbidden, Invalid, BadRequest, NoContent)
• ResultExtensions: static factory methods (Result.Ok(), Result<T>.NotFound(error), etc.)
• HttpResultExtensions: converts results to IResult for Minimal API endpoints
• ApiResponse / ApiResponse<T>: unified JSON response envelope
• ToFile(): binary and stream file responses
• ToServerSentEvents(): SSE streaming responses
• ToSignIn() / ToSignOut(): ASP.NET Core authentication responses

Usage

Creating Results (service layer)

using CoreMesh.Result.Extensions;

// Success
return Result<User>.Ok(user);
return Result<User>.Created(user);
return Result.NoContent();

// Failure
return Result<User>.NotFound(new Error("USER_001", "User not found"));
return Result<User>.Forbidden(new Error("AUTH_001", "Access denied"));
return Result<User>.BadRequest(new Error("INPUT_001", "Invalid input"));

// Validation errors
return Result<User>.Invalid(new Dictionary<string, string[]>
{
    ["Name"]  = ["Name is required", "Name too long"],
    ["Email"] = ["Invalid email format"]
});

Converting to HTTP Response (API layer)

using CoreMesh.Result.Http;

app.MapGet("/users/{id}", async (int id, UserService svc) =>
{
    var result = await svc.GetUserAsync(id);
    return result.ToHttpResult();
});

File Response

// byte[]
Result<byte[]> result = await fileService.GetPdfAsync(id);
return result.ToFile("application/pdf", "report.pdf");

// Stream
Result<Stream> result = await fileService.GetStreamAsync(id);
return result.ToFile("video/mp4", "video.mp4", enableRangeProcessing: true);

Server-Sent Events

// Simple stream
Result<IAsyncEnumerable<StockPrice>> result = service.GetPriceStream();
return result.ToServerSentEvents(eventType: "price");

// Custom SseItem per event
return result.ToServerSentEvents(() =>
    result.Data!.Select(p => new SseItem<StockPrice>(p, eventType: "price")));

Authentication

Result result = await authService.LoginAsync(req);
return result.ToSignIn(principal, authenticationScheme: "Cookies");

Result result = await authService.LogoutAsync();
return result.ToSignOut();

Response Envelope

All responses are wrapped in a consistent ApiResponse envelope.

Success (with data)

{
  "isSuccess": true,
  "code": "ok",
  "data": { "id": 1, "name": "David" }
}

Success (no data)

{
  "isSuccess": true,
  "code": "ok"
}

Failure

{
  "isSuccess": false,
  "code": "USER_001",
  "problem": {
    "status": 404,
    "title": "USER_001",
    "detail": "User not found"
  }
}

Validation Failure (422)

{
  "isSuccess": false,
  "code": "VALIDATION",
  "problem": {
    "status": 422,
    "title": "VALIDATION",
    "detail": "One or more validation errors occurred",
    "errors": {
      "Name":  ["Name is required"],
      "Email": ["Invalid email format"]
    }
  }
}

Status → HTTP Mapping

Design Notes

• The Result / Result<T> types have no dependency on ASP.NET Core — they are safe to use in domain or application layers
• HTTP concerns (ApiResponse, TypedResults) are isolated in the CoreMesh.Result.Http namespace
• NoContent, ToFile(), ToServerSentEvents(), ToSignIn(), and ToSignOut() do not wrap in ApiResponse since they carry non-JSON payloads or are handled by the auth middleware
• Result<T> constructors are protected — instances can only be created through factory methods in ResultExtensions